Stephen J Day f141480d98 Move common error codes to errcode package

Several error codes are generally useful but tied to the v2 specification
definitions. This change moves these error code definitions into the common
package for use by the health package, which is not tied to the v2 API.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

2015-08-11 11:50:58 -07:00

100 KiB

Raw Blame History

Docker Registry HTTP API V2

Introduction

The Docker Registry HTTP API is the protocol to facilitate distribution of images to the docker engine. It interacts with instances of the docker registry, which is a service to manage information about docker images and enable their distribution. The specification covers the operation of version 2 of this API, known as Docker Registry HTTP API V2.

While the V1 registry protocol is usable, there are several problems with the architecture that have led to this new version. The main driver of this specification these changes to the docker the image format, covered in docker/docker#8093. The new, self-contained image manifest simplifies image definition and improves security. This specification will build on that work, leveraging new properties of the manifest format to improve performance, reduce bandwidth usage and decrease the likelihood of backend corruption.

For relevant details and history leading up to this specification, please see the following issues:

Scope

This specification covers the URL layout and protocols of the interaction between docker registry and docker core. This will affect the docker core registry API and the rewrite of docker-registry. Docker registry implementations may implement other API endpoints, but they are not covered by this specification.

This includes the following features:

Namespace-oriented URI Layout
PUSH/PULL registry server for V2 image manifest format
Resumable layer PUSH support
V2 Client library implementation

While authentication and authorization support will influence this specification, details of the protocol will be left to a future specification. Relevant header definitions and error codes are present to provide an indication of what a client may encounter.

Future

There are features that have been discussed during the process of cutting this specification. The following is an incomplete list:

Immutable image references
Multiple architecture support
Migration from v2compatibility representation

These may represent features that are either out of the scope of this specification, the purview of another specification or have been deferred to a future version.

Use Cases

For the most part, the use cases of the former registry API apply to the new version. Differentiating use cases are covered below.

Image Verification

A docker engine instance would like to run verified image named "library/ubuntu", with the tag "latest". The engine contacts the registry, requesting the manifest for "library/ubuntu:latest". An untrusted registry returns a manifest. Before proceeding to download the individual layers, the engine verifies the manifest's signature, ensuring that the content was produced from a trusted source and no tampering has occured. After each layer is downloaded, the engine verifies the digest of the layer, ensuring that the content matches that specified by the manifest.

Resumable Push

Company X's build servers lose connectivity to docker registry before completing an image layer transfer. After connectivity returns, the build server attempts to re-upload the image. The registry notifies the build server that the upload has already been partially attempted. The build server responds by only sending the remaining data to complete the image file.

Resumable Pull

Company X is having more connectivity problems but this time in their deployment datacenter. When downloading an image, the connection is interrupted before completion. The client keeps the partial data and uses http Range requests to avoid downloading repeated data.

Layer Upload De-duplication

Company Y's build system creates two identical docker layers from build processes A and B. Build process A completes uploading the layer before B. When process B attempts to upload the layer, the registry indicates that its not necessary because the layer is already known.

If process A and B upload the same layer at the same time, both operations will proceed and the first to complete will be stored in the registry (Note: we may modify this to prevent dogpile with some locking mechanism).

Changes

The V2 specification has been written to work as a living document, specifying only what is certain and leaving what is not specified open or to future changes. Only non-conflicting additions should be made to the API and accepted changes should avoid preventing future changes from happening.

This section should be updated when changes are made to the specification, indicating what is different. Optionally, we may start marking parts of the specification to correspond with the versions enumerated here.

Each set of changes is given a letter corresponding to a set of modifications that were applied to the baseline specification. These are merely for reference and shouldn't be used outside the specification other than to identify a set of modifications.

f

Specify the delete API for layers and manifests.

e

Added support for listing registry contents.
Added pagination to tags API.
Added common approach to support pagination.

d

Allow repository name components to be one character.
Clarified that single component names are allowed.

c

Added section covering digest format.
Added more clarification that manifest cannot be deleted by tag.

b

Added capability of doing streaming upload to PATCH blob upload.
Updated PUT blob upload to no longer take final chunk, now requires entire data or no data.
Removed `416 Requested Range Not Satisfiable` response status from PUT blob upload.

a

Added support for immutable manifest references in manifest endpoints.
Deleting a manifest by tag has been deprecated.
Specified `Docker-Content-Digest` header for appropriate entities.
Added error code for unsupported operations.

Overview

This section covers client flows and details of the API endpoints. The URI layout of the new API is structured to support a rich authentication and authorization model by leveraging namespaces. All endpoints will be prefixed by the API version and the repository name:

/v2/<name>/

For example, an API endpoint that will work with the library/ubuntu repository, the URI prefix will be:

/v2/library/ubuntu/

This scheme provides rich access control over various operations and methods using the URI prefix and http methods that can be controlled in variety of ways.

Classically, repository names have always been two path components where each path component is less than 30 characters. The V2 registry API does not enforce this. The rules for a repository name are as follows:

A repository name is broken up into path components. A component of a repository name must be at least one lowercase, alpha-numeric characters, optionally separated by periods, dashes or underscores. More strictly, it must match the regular expression [a-z0-9]+(?:[._-][a-z0-9]+)*.
If a repository name has two or more path components, they must be separated by a forward slash ("/").
The total length of a repository name, including slashes, must be less the 256 characters.

These name requirements only apply to the registry API and should accept a superset of what is supported by other docker ecosystem components.

All endpoints should support aggressive http caching, compression and range headers, where appropriate. The new API attempts to leverage HTTP semantics where possible but may break from standards to implement targeted features.

For detail on individual endpoints, please see the Detail section.

Errors

Actionable failure conditions, covered in detail in their relevant sections, are reported as part of 4xx responses, in a json response body. One or more errors will be returned in the following format:

{
    "errors:" [{
            "code": <error identifier>,
            "message": <message describing condition>,
            "detail": <unstructured>
        },
        ...
    ]
}

The code field will be a unique identifier, all caps with underscores by convention. The message field will be a human readable string. The optional detail field may contain arbitrary json data providing information the client can use to resolve the issue.

While the client can take action on certain error codes, the registry may add new error codes over time. All client implementations should treat unknown error codes as UNKNOWN, allowing future error codes to be added without breaking API compatibility. For the purposes of the specification error codes will only be added and never removed.

For a complete account of all error codes, please see the Detail section.

API Version Check

A minimal endpoint, mounted at /v2/ will provide version support information based on its response statuses. The request format is as follows:

GET /v2/

If a 200 OK response is returned, the registry implements the V2(.1) registry API and the client may proceed safely with other V2 operations. Optionally, the response may contain information about the supported paths in the response body. The client should be prepared to ignore this data.

If a 401 Unauthorized response is returned, the client should take action based on the contents of the "WWW-Authenticate" header and try the endpoint again. Depending on access control setup, the client may still have to authenticate against different resources, even if this check succeeds.

If 404 Not Found response status, or other unexpected status, is returned, the client should proceed with the assumption that the registry does not implement V2 of the API.

When a 200 OK or 401 Unauthorized response is returned, the "Docker-Distribution-API-Version" header should be set to "registry/2.0". Clients may require this header value to determine if the endpoint serves this API. When this header is omitted, clients may fallback to an older API version.

Content Digests

This API design is driven heavily by content addressability. The core of this design is the concept of a content addressable identifier. It uniquely identifies content by taking a collision-resistant hash of the bytes. Such an identifier can be independently calculated and verified by selection of a common algorithm. If such an identifier can be communicated in a secure manner, one can retrieve the content from an insecure source, calculate it independently and be certain that the correct content was obtained. Put simply, the identifier is a property of the content.

To disambiguate from other concepts, we call this identifier a digest. A digest is a serialized hash result, consisting of a algorithm and hex portion. The algorithm identifies the methodology used to calculate the digest. The hex portion is the hex-encoded result of the hash.

We define a digest string to match the following grammar:

digest := algorithm ":" hex algorithm := /[A-Fa-f0-9_+.-]+/ hex := /[A-Fa-f0-9]+/

Some examples of digests include the following:

digest	description
sha256:6c3c624b58dbbcd3c0dd82b4c53f04194d1247c6eebdaab7c610cf7d66709b3b	Common sha256 based digest
tarsum.v1+sha256:6c3c624b58dbbcd3c0dd82b4c53f04194d1247c6eebdaab7c610cf7d66709b3b	Tarsum digest, used for legacy layer digests.

NOTE: While we show an example of using a tarsum digest, the security of tarsum has not been verified. It is recommended that most implementations use sha256 for interoperability.

While the algorithm does allow one to implement a wide variety of algorithms, compliant implementations should use sha256. Heavy processing of input before calculating a hash is discouraged to avoid degrading the uniqueness of the digest but some canonicalization may be performed to ensure consistent identifiers.

Let's use a simple example in pseudo-code to demonstrate a digest calculation:

let C = 'a small string'
let B = sha256(C)
let D = 'sha256:' + EncodeHex(B)
let ID(C) = D

Above, we have bytestring C passed into a function, SHA256, that returns a bytestring B, which is the hash of C. D gets the algorithm concatenated with the hex encoding of B. We then define the identifier of C to ID(C) as equal to D. A digest can be verified by independently calculating D and comparing it with identifier ID(C)

Digest Header

To provide verification of http content, any response may include a Docker- Content-Digest header. This will include the digest of the target entity returned in the response. For blobs, this is the entire blob content. For manifests, this is the manifest body without the signature content, also known as the JWS payload. Note that the commonly used canonicalization for digest calculation may be dependent on the mediatype of the content, such as with manifests.

The client may choose to ignore the header or may verify it to ensure content integrity and transport security. This is most important when fetching by a digest. To ensure security, the content should be verified against the digest used to fetch the content. At times, the returned digest may differ from that used to initiate a request. Such digests are considered to be from different domains, meaning they have different values for algorithm. In such a case, the client may choose to verify the digests in both domains or ignore the server's digest. To maintain security, the client must always verify the content against the digest used to fetch the content.

IMPORTANT: If a digest is used to fetch content, the client should use the same digest used to fetch the content to verify it. The header Docker- Content-Digest should not be trusted over the "local" digest.

Pulling An Image

An "image" is a combination of a JSON manifest and individual layer files. The process of pulling an image centers around retrieving these two components.

The first step in pulling an image is to retrieve the manifest. For reference, the relevant manifest fields for the registry are the following:

field	description
name	The name of the image.
tag	The tag for this version of the image.
fsLayers	A list of layer descriptors (including tarsum)
signature	A JWS used to verify the manifest content

For more information about the manifest format, please see docker/docker#8093.

When the manifest is in hand, the client must verify the signature to ensure the names and layers are valid. Once confirmed, the client will then use the tarsums to download the individual layers. Layers are stored in as blobs in the V2 registry API, keyed by their tarsum digest.

Pulling an Image Manifest

The image manifest can be fetched with the following url:

GET /v2/<name>/manifests/<reference>

The name and reference parameter identify the image and are required. The reference may include a tag or digest.

A 404 Not Found response will be returned if the image is unknown to the registry. If the image exists and the response is successful, the image manifest will be returned, with the following format (see docker/docker#8093 for details):

{
   "name": <name>,
   "tag": <tag>,
   "fsLayers": [
      {
         "blobSum": <tarsum>
      },
      ...
    ]
   ],
   "history": <v1 images>,
   "signature": <JWS>
}

The client should verify the returned manifest signature for authenticity before fetching layers.

Pulling a Layer

Layers are stored in the blob portion of the registry, keyed by tarsum digest. Pulling a layer is carried out by a standard http request. The URL is as follows:

GET /v2/<name>/blobs/<tarsum>

Access to a layer will be gated by the name of the repository but is identified uniquely in the registry by tarsum. The tarsum parameter is an opaque field, to be interpreted by the tarsum library.

This endpoint may issue a 307 (302 for <HTTP 1.1) redirect to another service for downloading the layer and clients should be prepared to handle redirects.

This endpoint should support aggressive HTTP caching for image layers. Support for Etags, modification dates and other cache control headers should be included. To allow for incremental downloads, Range requests should be supported, as well.

Pushing An Image

Pushing an image works in the opposite order as a pull. After assembling the image manifest, the client must first push the individual layers. When the layers are fully pushed into the registry, the client should upload the signed manifest.

The details of each step of the process are covered in the following sections.

Pushing a Layer

All layer uploads use two steps to manage the upload process. The first step starts the upload in the registry service, returning a url to carry out the second step. The second step uses the upload url to transfer the actual data. Uploads are started with a POST request which returns a url that can be used to push data and check upload status.

The Location header will be used to communicate the upload location after each request. While it won't change in the this specification, clients should use the most recent value returned by the API.

Starting An Upload

To begin the process, a POST request should be issued in the following format:

POST /v2/<name>/blobs/uploads/

The parameters of this request are the image namespace under which the layer will be linked. Responses to this request are covered below.

Existing Layers

The existence of a layer can be checked via a HEAD request to the blob store API. The request should be formatted as follows:

HEAD /v2/<name>/blobs/<digest>

If the layer with the tarsum specified in digest is available, a 200 OK response will be received, with no actual body content (this is according to http specification). The response will look as follows:

200 OK
Content-Length: <length of blob>
Docker-Content-Digest: <digest>

When this response is received, the client can assume that the layer is already available in the registry under the given name and should take no further action to upload the layer. Note that the binary digests may differ for the existing registry layer, but the tarsums will be guaranteed to match.

Uploading the Layer

If the POST request is successful, a 202 Accepted response will be returned with the upload URL in the Location header:

202 Accepted
Location: /v2/<name>/blobs/uploads/<uuid>
Range: bytes=0-<offset>
Content-Length: 0
Docker-Upload-UUID: <uuid>

The rest of the upload process can be carried out with the returned url, called the "Upload URL" from the Location header. All responses to the upload url, whether sending data or getting status, will be in this format. Though the URI format (/v2/<name>/blobs/uploads/<uuid>) for the Location header is specified, clients should treat it as an opaque url and should never try to assemble the it. While the uuid parameter may be an actual UUID, this proposal imposes no constraints on the format and clients should never impose any.

If clients need to correlate local upload state with remote upload state, the contents of the Docker-Upload-UUID header should be used. Such an id can be used to key the last used location header when implementing resumable uploads.

Upload Progress

The progress and chunk coordination of the upload process will be coordinated through the Range header. While this is a non-standard use of the Range header, there are examples of similar approaches in APIs with heavy use. For an upload that just started, for an example with a 1000 byte layer file, the Range header would be as follows:

Range: bytes=0-0

To get the status of an upload, issue a GET request to the upload URL:

GET /v2/<name>/blobs/uploads/<uuid>
Host: <registry host>

The response will be similar to the above, except will return 204 status:

204 No Content
Location: /v2/<name>/blobs/uploads/<uuid>
Range: bytes=0-<offset>
Docker-Upload-UUID: <uuid>

Note that the HTTP Range header byte ranges are inclusive and that will be honored, even in non-standard use cases.

Monolithic Upload

A monolithic upload is simply a chunked upload with a single chunk and may be favored by clients that would like to avoided the complexity of chunking. To carry out a "monolithic" upload, one can simply put the entire content blob to the provided URL:

PUT /v2/<name>/blobs/uploads/<uuid>?digest=<tarsum>[&digest=sha256:<hex digest>]
Content-Length: <size of layer>
Content-Type: application/octet-stream

<Layer Binary Data>

The "digest" parameter must be included with the PUT request. Please see the Completed Upload section for details on the parameters and expected responses.

Additionally, the upload can be completed with a single POST request to the uploads endpoint, including the "size" and "digest" parameters:

POST /v2/<name>/blobs/uploads/?digest=<tarsum>[&digest=sha256:<hex digest>]
Content-Length: <size of layer>
Content-Type: application/octet-stream
  
<Layer Binary Data>

On the registry service, this should allocate a download, accept and verify the data and return the same response as the final chunk of an upload. If the POST request fails collecting the data in any way, the registry should attempt to return an error response to the client with the Location header providing a place to continue the download.

The single POST method is provided for convenience and most clients should implement POST + PUT to support reliable resume of uploads.

Chunked Upload

To carry out an upload of a chunk, the client can specify a range header and only include that part of the layer file:

PATCH /v2/<name>/blobs/uploads/<uuid>
Content-Length: <size of chunk>
Content-Range: <start of range>-<end of range>
Content-Type: application/octet-stream

<Layer Chunk Binary Data>

There is no enforcement on layer chunk splits other than that the server must receive them in order. The server may enforce a minimum chunk size. If the server cannot accept the chunk, a 416 Requested Range Not Satisfiable response will be returned and will include a Range header indicating the current status:

416 Requested Range Not Satisfiable
Location: /v2/<name>/blobs/uploads/<uuid>
Range: 0-<last valid range>
Content-Length: 0
Docker-Upload-UUID: <uuid>

If this response is received, the client should resume from the "last valid range" and upload the subsequent chunk. A 416 will be returned under the following conditions:

Invalid Content-Range header format
Out of order chunk: the range of the next chunk must start immediately after the "last valid range" from the previous response.

When a chunk is accepted as part of the upload, a 202 Accepted response will be returned, including a Range header with the current upload status:

202 Accepted
Location: /v2/<name>/blobs/uploads/<uuid>
Range: bytes=0-<offset>
Content-Length: 0
Docker-Upload-UUID: <uuid>

Completed Upload

For an upload to be considered complete, the client must submit a PUT request on the upload endpoint with a digest parameter. If it is not provided, the upload will not be considered complete. The format for the final chunk will be as follows:

PUT /v2/<name>/blob/uploads/<uuid>?digest=<tarsum>[&digest=sha256:<hex digest>]
Content-Length: <size of chunk>
Content-Range: <start of range>-<end of range>
Content-Type: application/octet-stream

<Last Layer Chunk Binary Data>

Optionally, if all chunks have already been uploaded, a PUT request with a digest parameter and zero-length body may be sent to complete and validated the upload. Multiple "digest" parameters may be provided with different digests. The server may verify none or all of them but must notify the client if the content is rejected.

When the last chunk is received and the layer has been validated, the client will receive a 201 Created response:

201 Created
Location: /v2/<name>/blobs/<tarsum>
Content-Length: 0
Docker-Content-Digest: <digest>

The Location header will contain the registry URL to access the accepted layer file. The Docker-Content-Digest header returns the canonical digest of the uploaded blob which may differ from the provided digest. Most clients may ignore the value but if it is used, the client should verify the value against the uploaded blob data.

Digest Parameter

The "digest" parameter is designed as an opaque parameter to support verification of a successful transfer. The initial version of the registry API will support a tarsum digest, in the standard tarsum format. For example, a HTTP URI parameter might be as follows:

tarsum.v1+sha256:6c3c624b58dbbcd3c0dd82b4c53f04194d1247c6eebdaab7c610cf7d66709b3b

Given this parameter, the registry will verify that the provided content does result in this tarsum. Optionally, the registry can support other other digest parameters for non-tarfile content stored as a layer. A regular hash digest might be specified as follows:

sha256:6c3c624b58dbbcd3c0dd82b4c53f04194d1247c6eebdaab7c610cf7d66709b3b

Such a parameter would be used to verify that the binary content (as opposed to the tar content) would be verified at the end of the upload process.

For the initial version, registry servers are only required to support the tarsum format.

Canceling an Upload

An upload can be cancelled by issuing a DELETE request to the upload endpoint. The format will be as follows:

DELETE /v2/<name>/blobs/uploads/<uuid>

After this request is issued, the upload uuid will no longer be valid and the registry server will dump all intermediate data. While uploads will time out if not completed, clients should issue this request if they encounter a fatal error but still have the ability to issue an http request.

Errors

If an 502, 503 or 504 error is received, the client should assume that the download can proceed due to a temporary condition, honoring the appropriate retry mechanism. Other 5xx errors should be treated as terminal.

If there is a problem with the upload, a 4xx error will be returned indicating the problem. After receiving a 4xx response (except 416, as called out above), the upload will be considered failed and the client should take appropriate action.

Note that the upload url will not be available forever. If the upload uuid is unknown to the registry, a 404 Not Found response will be returned and the client must restart the upload process.

Deleting a Layer

A layer may be deleted from the registry via its name and digest. A delete may be issued with the following request format:

DELETE /v2/<name>/blobs/<digest>

If the blob exists and has been successfully deleted, the following response will be issued:

202 Accepted
Content-Length: None

If the blob had already been deleted or did not exist, a 404 Not Found response will be issued instead.

If a layer is deleted which is referenced by a manifest in the registry, then the complete images will not be resolvable.

Pushing an Image Manifest

Once all of the layers for an image are uploaded, the client can upload the image manifest. An image can be pushed using the following request format:

PUT /v2/<name>/manifests/<reference>

{
   "name": <name>,
   "tag": <tag>,
   "fsLayers": [
      {
         "blobSum": <tarsum>
      },
      ...
    ]
   ],
   "history": <v1 images>,
   "signature": <JWS>,
   ...
}

The name and reference fields of the response body must match those specified in the URL. The reference field may be a "tag" or a "digest".

If there is a problem with pushing the manifest, a relevant 4xx response will be returned with a JSON error message. Please see the _PUT Manifest section for details on possible error codes that may be returned.

If one or more layers are unknown to the registry, BLOB_UNKNOWN errors are returned. The detail field of the error response will have a digest field identifying the missing blob, which will be a tarsum. An error is returned for each unknown blob. The response format is as follows:

{
    "errors:" [{
            "code": "BLOB_UNKNOWN",
            "message": "blob unknown to registry",
            "detail": {
                "digest": <tarsum>
            }
        },
        ...
    ]
}

Listing Repositories

Images are stored in collections, known as a repository, which is keyed by a name, as seen throughout the API specification. A registry instance may contain several repositories. The list of available repositories is made available through the catalog.

The catalog for a given registry can be retrieved with the following request:

GET /v2/_catalog

The response will be in the following format:

200 OK
Content-Type: application/json

{
  "repositories": [
    <name>,
    ...
  ]
}

Note that the contents of the response are specific to the registry implementation. Some registries may opt to provide a full catalog output, limit it based on the user's access level or omit upstream results, if providing mirroring functionality. Subsequently, the presence of a repository in the catalog listing only means that the registry may provide access to the repository at the time of the request. Conversely, a missing entry does not mean that the registry does not have the repository. More succinctly, the presence of a repository only guarantees that it is there but not that it is not there.

For registries with a large number of repositories, this response may be quite large. If such a response is expected, one should use pagination.

Pagination

Paginated catalog results can be retrieved by adding an n parameter to the request URL, declaring that the response should be limited to n results. Starting a paginated flow begins as follows:

GET /v2/_catalog?n=<integer>

The above specifies that a catalog response should be returned, from the start of the result set, ordered lexically, limiting the number of results to n. The response to such a request would look as follows:

200 OK
Content-Type: application/json
Link: <<url>?n=<n from the request>&last=<last repository in response>>; rel="next"

{
  "repositories": [
    <name>,
    ...
  ]
}

The above includes the first n entries from the result set. To get the next n entries, one can create a URL where the argument last has the value from repositories[len(repositories)-1]. If there are indeed more results, the URL for the next block is encoded in an RFC5988 Link header, as a "next" relation. The presence of the Link header communicates to the client that the entire result set has not been returned and another request must be issued. If the header is not present, the client can assume that all results have been recieved.

NOTE: In the request template above, note that the brackets are required. For example, if the url is http://example.com/v2/_catalog?n=20&last=b, the value of the header would be <http://example.com/v2/_catalog?n=20&last=b>; rel="next". Please see RFC5988 for details.

Compliant client implementations should always use the Link header value when proceeding through results linearly. The client may construct URLs to skip forward in the catalog.

To get the next result set, a client would issue the request as follows, using the URL encoded in the described Link header:

GET /v2/_catalog?n=<n from the request>&last=<last repository value from previous response>

The above process should then be repeated until the Link header is no longer set.

The catalog result set is represented abstractly as a lexically sorted list, where the position in that list can be specified by the query term last. The entries in the response start after the term specified by last, up to n entries.

The behavior of last is quite simple when demonstrated with an example. Let us say the registry has the following repositories:

a
b
c
d

If the value of n is 2, a and b will be returned on the first response. The Link header returned on the response will have n set to 2 and last set to b:

Link: <<url>?n=2&last=b>; rel="next"

The client can then issue the request with above value from the Link header, receiving the values c and d. Note that n may change on second to last response or be omitted fully, if the server may so choose.

Listing Image Tags

It may be necessary to list all of the tags under a given repository. The tags for an image repository can be retrieved with the following request:

GET /v2/<name>/tags/list

The response will be in the following format:

200 OK
Content-Type: application/json

{
    "name": <name>,
    "tags": [
        <tag>,
        ...
    ]
}

For repositories with a large number of tags, this response may be quite large. If such a response is expected, one should use the pagination.

Pagination

Paginated tag results can be retrieved by adding the appropriate parameters to the request URL described above. The behavior of tag pagination is identical to that specified for catalog pagination. We cover a simple flow to highlight any differences.

Starting a paginated flow may begin as follows:

GET /v2/<name>/tags/list?n=<integer>

The above specifies that a tags response should be returned, from the start of the result set, ordered lexically, limiting the number of results to n. The response to such a request would look as follows:

200 OK
Content-Type: application/json
Link: <<url>?n=<n from the request>&last=<last tag value from previous response>>; rel="next"

{
  "name": <name>,
  "tags": [
    <tag>,
    ...
  ]
}

To get the next result set, a client would issue the request as follows, using the value encoded in the RFC5988 Link header:

GET /v2/<name>/tags/list?n=<n from the request>&last=<last tag value from previous response>

The above process should then be repeated until the Link header is no longer set in the response. The behavior of the last parameter, the provided response result, lexical ordering and encoding of the Link header are identical to that of catalog pagination.

Deleting an Image

An image may be deleted from the registry via its name and reference. A delete may be issued with the following request format:

DELETE /v2/<name>/manifests/<reference>

For deletes, reference must be a digest or the delete will fail. If the image exists and has been successfully deleted, the following response will be issued:

202 Accepted
Content-Length: None

If the image had already been deleted or did not exist, a 404 Not Found response will be issued instead.

Detail

Note

: This section is still under construction. For the purposes of implementation, if any details below differ from the described request flows above, the section below should be corrected. When they match, this note should be removed.

The behavior of the endpoints are covered in detail in this section, organized by route and entity. All aspects of the request and responses are covered, including headers, parameters and body formats. Examples of requests and their corresponding responses, with success and failure, are enumerated.

Note

: The sections on endpoint detail are arranged with an example request, a description of the request, followed by information about that request.

A list of methods and URIs are covered in the table below:

Method	Path	Entity	Description
GET	`/v2/`	Base	Check that the endpoint implements Docker Registry API V2.
GET	`/v2/<name>/tags/list`	Tags	Fetch the tags under the repository identified by `name`.
GET	`/v2/<name>/manifests/<reference>`	Manifest	Fetch the manifest identified by `name` and `reference` where `reference` can be a tag or digest.
PUT	`/v2/<name>/manifests/<reference>`	Manifest	Put the manifest identified by `name` and `reference` where `reference` can be a tag or digest.
DELETE	`/v2/<name>/manifests/<reference>`	Manifest	Delete the manifest identified by `name` and `reference`. Note that a manifest can only be deleted by `digest`.
GET	`/v2/<name>/blobs/<digest>`	Blob	Retrieve the blob from the registry identified by `digest`. A `HEAD` request can also be issued to this endpoint to obtain resource information without receiving all data.
DELETE	`/v2/<name>/blobs/<digest>`	Blob	Delete the blob identified by `name` and `digest`
POST	`/v2/<name>/blobs/uploads/`	Initiate Blob Upload	Initiate a resumable blob upload. If successful, an upload location will be provided to complete the upload. Optionally, if the `digest` parameter is present, the request body will be used to complete the upload in a single request.
GET	`/v2/<name>/blobs/uploads/<uuid>`	Blob Upload	Retrieve status of upload identified by `uuid`. The primary purpose of this endpoint is to resolve the current status of a resumable upload.
PATCH	`/v2/<name>/blobs/uploads/<uuid>`	Blob Upload	Upload a chunk of data for the specified upload.
PUT	`/v2/<name>/blobs/uploads/<uuid>`	Blob Upload	Complete the upload specified by `uuid`, optionally appending the body as the final chunk.
DELETE	`/v2/<name>/blobs/uploads/<uuid>`	Blob Upload	Cancel outstanding upload processes, releasing associated resources. If this is not called, the unfinished uploads will eventually timeout.
GET	`/v2/_catalog`	Catalog	Retrieve a sorted, json list of repositories available in the registry.

The detail for each endpoint is covered in the following sections.

Errors

The error codes encountered via the API are enumerated in the following table:

Code	Message	Description
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`MANIFEST_BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a manifest blob is unknown to the registry.
`MANIFEST_INVALID`	manifest invalid	During upload, manifests undergo several checks ensuring validity. If those checks fail, this error may be returned, unless a more specific error is included. The detail will contain information the failed validation.
`MANIFEST_UNKNOWN`	manifest unknown	This error is returned when the manifest, identified by name and tag is unknown to the repository.
`MANIFEST_UNVERIFIED`	manifest failed signature verification	During manifest upload, if the manifest fails signature verification, this error will be returned.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`SIZE_INVALID`	provided length did not match content length	When a layer is uploaded, the provided size will be checked against the uploaded content. If they do not match, this error will be returned.
`TAG_INVALID`	manifest tag did not match URI	During a manifest upload, if the tag in the manifest does not match the uri tag, this error will be returned.
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.
`UNSUPPORTED`	The operation is unsupported.	The operation was unsupported due to a missing implementation or invalid set of parameters.

Base

Base V2 API route. Typically, this can be used for lightweight version checks and to validate registry authorization.

GET Base

Check that the endpoint implements Docker Registry API V2.

GET /v2/
Host: <registry host>
Authorization: <scheme> <token>

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.

On Success: OK

200 OK

The API implements V2 protocol and is accessible.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The client is not authorized to access the registry.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found

The registry does not implement the V2 API.

Name	Kind	Description
`name`	path	Name of the target repository.
`n`	query	Limit the number of entries in each response. It not present, all entries will be returned.
`last`	query	Result set will include values lexically after last.

Name	Description
`Docker-Content-Digest`	Digest of the targeted content for the request.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The named manifest is not known to the registry.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`MANIFEST_UNKNOWN`	manifest unknown	This error is returned when the manifest, identified by name and tag is unknown to the repository.

PUT Manifest

Put the manifest identified by name and reference where reference can be a tag or digest.

PUT /v2/<name>/manifests/<reference>
Host: <registry host>
Authorization: <scheme> <token>
Content-Type: application/json; charset=utf-8

{
   "name": <name>,
   "tag": <tag>,
   "fsLayers": [
      {
         "blobSum": "<digest>"
      },
      ...
    ]
   ],
   "history": <v1 images>,
   "signature": <JWS>
}

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`reference`	path	Tag or digest of the target manifest.

On Success: Created

201 Created
Location: <url>
Content-Length: 0
Docker-Content-Digest: <digest>

The manifest has been accepted by the registry and is stored under the specified name and tag.

The following headers will be returned with the response:

Name	Description
`Location`	The canonical location url of the uploaded manifest.
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Content-Digest`	Digest of the targeted content for the request.

On Failure: Invalid Manifest

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The received manifest was invalid in some way, as described by the error codes. The client should resolve the issue and retry the request.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`TAG_INVALID`	manifest tag did not match URI	During a manifest upload, if the tag in the manifest does not match the uri tag, this error will be returned.
`MANIFEST_INVALID`	manifest invalid	During upload, manifests undergo several checks ensuring validity. If those checks fail, this error may be returned, unless a more specific error is included. The detail will contain information the failed validation.
`MANIFEST_UNVERIFIED`	manifest failed signature verification	During manifest upload, if the manifest fails signature verification, this error will be returned.
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.

On Failure: Unauthorized

401 Unauthorized
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The client does not have permission to push to the repository.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Missing Layer(s)

400 Bad Request
Content-Type: application/json; charset=utf-8

{
    "errors:" [{
            "code": "BLOB_UNKNOWN",
            "message": "blob unknown to registry",
            "detail": {
                "digest": "<digest>"
            }
        },
        ...
    ]
}

One or more layers may be missing during a manifest upload. If so, the missing layers will be enumerated in the error response.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

DELETE Manifest

Delete the manifest identified by name and reference. Note that a manifest can only be deleted by digest.

DELETE /v2/<name>/manifests/<reference>
Host: <registry host>
Authorization: <scheme> <token>

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`reference`	path	Tag or digest of the target manifest.

On Success: Accepted

202 Accepted

On Failure: Invalid Name or Reference

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The specified name or reference were invalid and the delete was unable to proceed.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`TAG_INVALID`	manifest tag did not match URI	During a manifest upload, if the tag in the manifest does not match the uri tag, this error will be returned.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Unknown Manifest

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The specified name or reference are unknown to the registry and the delete was unable to proceed. Clients can assume the manifest was already deleted if this response is returned.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`MANIFEST_UNKNOWN`	manifest unknown	This error is returned when the manifest, identified by name and tag is unknown to the repository.

Blob

Operations on blobs identified by name and digest. Used to fetch or delete layers by digest.

GET Blob

Retrieve the blob from the registry identified by digest. A HEAD request can also be issued to this endpoint to obtain resource information without receiving all data.

Fetch Blob

GET /v2/<name>/blobs/<digest>
Host: <registry host>
Authorization: <scheme> <token>

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`digest`	path	Digest of desired blob.

On Success: OK

200 OK
Content-Length: <length>
Docker-Content-Digest: <digest>
Content-Type: application/octet-stream

<blob binary data>

The blob identified by digest is available. The blob content will be present in the body of the request.

The following headers will be returned with the response:

Name	Description
`Content-Length`	The length of the requested blob content.
`Docker-Content-Digest`	Digest of the targeted content for the request.

On Success: Temporary Redirect

307 Temporary Redirect
Location: <blob location>
Docker-Content-Digest: <digest>

The blob identified by digest is available at the provided location.

The following headers will be returned with the response:

Name	Description
`Location`	The location where the layer should be accessible.
`Docker-Content-Digest`	Digest of the targeted content for the request.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was a problem with the request that needs to be addressed by the client, such as an invalid name or tag.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The blob, identified by name and digest, is unknown to the registry.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.

Fetch Blob Part

GET /v2/<name>/blobs/<digest>
Host: <registry host>
Authorization: <scheme> <token>
Range: bytes=<start>-<end>

This endpoint may also support RFC7233 compliant range requests. Support can be detected by issuing a HEAD request. If the header Accept-Range: bytes is returned, range requests can be used to fetch partial content.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Range`	header	HTTP Range header specifying blob chunk.
`name`	path	Name of the target repository.
`digest`	path	Digest of desired blob.

On Success: Partial Content

206 Partial Content
Content-Length: <length>
Content-Range: bytes <start>-<end>/<size>
Content-Type: application/octet-stream

<blob binary data>

The blob identified by digest is available. The specified chunk of blob content will be present in the body of the request.

The following headers will be returned with the response:

Name	Description
`Content-Length`	The length of the requested blob chunk.
`Content-Range`	Content range of blob chunk.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was a problem with the request that needs to be addressed by the client, such as an invalid name or tag.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.

On Failure: Requested Range Not Satisfiable

416 Requested Range Not Satisfiable

The range specification cannot be satisfied for the requested content. This can happen when the range is not formatted correctly or if the range is outside of the valid size of the content.

DELETE Blob

Delete the blob identified by name and digest

DELETE /v2/<name>/blobs/<digest>
Host: <registry host>
Authorization: <scheme> <token>

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`digest`	path	Digest of desired blob.

On Success: Accepted

202 Accepted
Content-Length: 0
Docker-Content-Digest: <digest>

The following headers will be returned with the response:

Name	Description
`Content-Length`	0
`Docker-Content-Digest`	Digest of the targeted content for the request.

On Failure: Invalid Name or Digest

400 Bad Request

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The blob, identified by name and digest, is unknown to the registry.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_UNKNOWN`	repository name not known to registry	This is returned if the name used during an operation is unknown to the registry.
`BLOB_UNKNOWN`	blob unknown to registry	This error may be returned when a blob is unknown to the registry in a specified repository. This can be returned with a standard get or if a manifest references an unknown layer during upload.

On Failure: Method Not Allowed

405 Method Not Allowed
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

Delete is not enabled on the registry

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNSUPPORTED`	The operation is unsupported.	The operation was unsupported due to a missing implementation or invalid set of parameters.

Initiate Blob Upload

Initiate a blob upload. This endpoint can be used to create resumable uploads or monolithic uploads.

POST Initiate Blob Upload

Initiate a resumable blob upload. If successful, an upload location will be provided to complete the upload. Optionally, if the digest parameter is present, the request body will be used to complete the upload in a single request.

Initiate Monolithic Blob Upload

POST /v2/<name>/blobs/uploads/?digest=<digest>
Host: <registry host>
Authorization: <scheme> <token>
Content-Length: <length of blob>
Content-Type: application/octect-stream

<binary data>

Upload a blob identified by the digest parameter in single request. This upload will not be resumable unless a recoverable error is returned.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Content-Length`	header
`name`	path	Name of the target repository.
`digest`	query	Digest of uploaded blob. If present, the upload will be completed, in a single request, with contents of the request body as the resulting blob.

On Success: Created

201 Created
Location: <blob location>
Content-Length: 0
Docker-Upload-UUID: <uuid>

The blob has been created in the registry and is available at the provided location.

The following headers will be returned with the response:

Name	Description
`Location`
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Upload-UUID`	Identifies the docker upload uuid for the current request.

On Failure: Invalid Name or Digest

400 Bad Request

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to push to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

Initiate Resumable Blob Upload

POST /v2/<name>/blobs/uploads/
Host: <registry host>
Authorization: <scheme> <token>
Content-Length: 0

Initiate a resumable blob upload with an empty request body.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Content-Length`	header	The `Content-Length` header must be zero and the body must be empty.
`name`	path	Name of the target repository.

On Success: Accepted

202 Accepted
Content-Length: 0
Location: /v2/<name>/blobs/uploads/<uuid>
Range: 0-0
Docker-Upload-UUID: <uuid>

The upload has been created. The Location header must be used to complete the upload. The response should be identical to a GET request on the contents of the returned Location header.

The following headers will be returned with the response:

Name	Description
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Location`	The location of the created upload. Clients should use the contents verbatim to complete the upload, adding parameters where required.
`Range`	Range header indicating the progress of the upload. When starting an upload, it will return an empty range, since no content has been received.
`Docker-Upload-UUID`	Identifies the docker upload uuid for the current request.

On Failure: Invalid Name or Digest

400 Bad Request

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to push to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

Blob Upload

Interact with blob uploads. Clients should never assemble URLs for this endpoint and should only take it through the Location header on related API requests. The Location header and its parameters should be preserved by clients, using the latest value returned via upload related API calls.

GET Blob Upload

Retrieve status of upload identified by uuid. The primary purpose of this endpoint is to resolve the current status of a resumable upload.

GET /v2/<name>/blobs/uploads/<uuid>
Host: <registry host>
Authorization: <scheme> <token>

Retrieve the progress of the current upload, as reported by the Range header.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`uuid`	path	A uuid identifying the upload. This field can accept characters that match `[a-zA-Z0-9-_.=]+`.

On Success: Upload Progress

204 No Content
Range: 0-<offset>
Content-Length: 0
Docker-Upload-UUID: <uuid>

The upload is known and in progress. The last received offset is available in the Range header.

The following headers will be returned with the response:

Name	Description
`Range`	Range indicating the current progress of the upload.
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Upload-UUID`	Identifies the docker upload uuid for the current request.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was an error processing the upload and it must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The upload is unknown to the registry. The upload must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.

PATCH Blob Upload

Upload a chunk of data for the specified upload.

Stream upload

PATCH /v2/<name>/blobs/uploads/<uuid>
Host: <registry host>
Authorization: <scheme> <token>
Content-Type: application/octet-stream

<binary data>

Upload a stream of data to upload without completing the upload.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`name`	path	Name of the target repository.
`uuid`	path	A uuid identifying the upload. This field can accept characters that match `[a-zA-Z0-9-_.=]+`.

On Success: Data Accepted

204 No Content
Location: /v2/<name>/blobs/uploads/<uuid>
Range: 0-<offset>
Content-Length: 0
Docker-Upload-UUID: <uuid>

The stream of data has been accepted and the current progress is available in the range header. The updated upload location is available in the Location header.

The following headers will be returned with the response:

Name	Description
`Location`	The location of the upload. Clients should assume this changes after each request. Clients should use the contents verbatim to complete the upload, adding parameters where required.
`Range`	Range indicating the current progress of the upload.
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Upload-UUID`	Identifies the docker upload uuid for the current request.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was an error processing the upload and it must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to push to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The upload is unknown to the registry. The upload must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.

Chunked upload

PATCH /v2/<name>/blobs/uploads/<uuid>
Host: <registry host>
Authorization: <scheme> <token>
Content-Range: <start of range>-<end of range, inclusive>
Content-Length: <length of chunk>
Content-Type: application/octet-stream

<binary chunk>

Upload a chunk of data to specified upload without completing the upload. The data will be uploaded to the specified Content Range.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Content-Range`	header	Range of bytes identifying the desired block of content represented by the body. Start must the end offset retrieved via status check plus one. Note that this is a non-standard use of the `Content-Range` header.
`Content-Length`	header	Length of the chunk being uploaded, corresponding the length of the request body.
`name`	path	Name of the target repository.
`uuid`	path	A uuid identifying the upload. This field can accept characters that match `[a-zA-Z0-9-_.=]+`.

On Success: Chunk Accepted

204 No Content
Location: /v2/<name>/blobs/uploads/<uuid>
Range: 0-<offset>
Content-Length: 0
Docker-Upload-UUID: <uuid>

The chunk of data has been accepted and the current progress is available in the range header. The updated upload location is available in the Location header.

The following headers will be returned with the response:

Name	Description
`Location`	The location of the upload. Clients should assume this changes after each request. Clients should use the contents verbatim to complete the upload, adding parameters where required.
`Range`	Range indicating the current progress of the upload.
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Upload-UUID`	Identifies the docker upload uuid for the current request.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was an error processing the upload and it must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to push to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The upload is unknown to the registry. The upload must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.

On Failure: Requested Range Not Satisfiable

416 Requested Range Not Satisfiable

The Content-Range specification cannot be accepted, either because it does not overlap with the current progress or it is invalid.

PUT Blob Upload

Complete the upload specified by uuid, optionally appending the body as the final chunk.

PUT /v2/<name>/blobs/uploads/<uuid>?digest=<digest>
Host: <registry host>
Authorization: <scheme> <token>
Content-Length: <length of data>
Content-Type: application/octet-stream

<binary data>

Complete the upload, providing all the data in the body, if necessary. A request without a body will just complete the upload with previously uploaded content.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Content-Length`	header	Length of the data being uploaded, corresponding to the length of the request body. May be zero if no data is provided.
`name`	path	Name of the target repository.
`uuid`	path	A uuid identifying the upload. This field can accept characters that match `[a-zA-Z0-9-_.=]+`.
`digest`	query	Digest of uploaded blob.

On Success: Upload Complete

204 No Content
Location: <blob location>
Content-Range: <start of range>-<end of range, inclusive>
Content-Length: 0
Docker-Content-Digest: <digest>

The upload has been completed and accepted by the registry. The canonical location will be available in the Location header.

The following headers will be returned with the response:

Name	Description
`Location`	The canonical location of the blob for retrieval
`Content-Range`	Range of bytes identifying the desired block of content represented by the body. Start must match the end of offset retrieved via status check. Note that this is a non-standard use of the `Content-Range` header.
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.
`Docker-Content-Digest`	Digest of the targeted content for the request.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

There was an error processing the upload and it must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`DIGEST_INVALID`	provided digest did not match uploaded content	When a blob is uploaded, the registry will check that the content matches the digest provided by the client. The error may include a detail structure with the key "digest", including the invalid digest string. This error may also be returned when a manifest includes an invalid layer digest.
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to push to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The upload is unknown to the registry. The upload must be restarted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.

DELETE Blob Upload

Cancel outstanding upload processes, releasing associated resources. If this is not called, the unfinished uploads will eventually timeout.

DELETE /v2/<name>/blobs/uploads/<uuid>
Host: <registry host>
Authorization: <scheme> <token>
Content-Length: 0

Cancel the upload specified by uuid.

The following parameters should be specified on the request:

Name	Kind	Description
`Host`	header	Standard HTTP Host Header. Should be set to the registry host.
`Authorization`	header	An RFC7235 compliant authorization header.
`Content-Length`	header	The `Content-Length` header must be zero and the body must be empty.
`name`	path	Name of the target repository.
`uuid`	path	A uuid identifying the upload. This field can accept characters that match `[a-zA-Z0-9-_.=]+`.

On Success: Upload Deleted

204 No Content
Content-Length: 0

The upload has been successfully deleted.

The following headers will be returned with the response:

Name	Description
`Content-Length`	The `Content-Length` header must be zero and the body must be empty.

On Failure: Bad Request

400 Bad Request
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

An error was encountered processing the delete. The client may ignore this error.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`NAME_INVALID`	invalid repository name	Invalid repository name encountered either during manifest validation or any API operation.
`BLOB_UPLOAD_INVALID`	blob upload invalid	The blob upload encountered an error and can no longer proceed.

On Failure: Unauthorized

401 Unauthorized
WWW-Authenticate: <scheme> realm="<realm>", ..."
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": "UNAUTHORIZED",
            "message": "access to the requested resource is not authorized",
            "detail": ...
        },
        ...
    ]
}

The client does not have access to the repository.

The following headers will be returned on the response:

Name	Description
`WWW-Authenticate`	An RFC7235 compliant authentication challenge header.
`Content-Length`	Length of the JSON error response body.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`UNAUTHORIZED`	access to the requested resource is not authorized	The access controller denied access for the operation on a resource. Often this will be accompanied by a 401 Unauthorized response status.

On Failure: Not Found

404 Not Found
Content-Type: application/json; charset=utf-8

{
	"errors:" [
	    {
            "code": <error code>,
            "message": "<error message>",
            "detail": ...
        },
        ...
    ]
}

The upload is unknown to the registry. The client may ignore this error and assume the upload has been deleted.

The error codes that may be included in the response body are enumerated below:

Code	Message	Description
`BLOB_UPLOAD_UNKNOWN`	blob upload unknown to registry	If a blob upload has been cancelled or was never started, this error code may be returned.

Catalog

List a set of available repositories in the local registry cluster. Does not provide any indication of what may be available upstream. Applications can only determine if a repository is available but not if it is not available.

GET Catalog

Retrieve a sorted, json list of repositories available in the registry.

Catalog Fetch Complete

GET /v2/_catalog

Request an unabridged list of repositories available.

On Success: OK

200 OK
Content-Length: <length>
Content-Type: application/json; charset=utf-8

{
	"repositories": [
		<name>,
		...
	]
}

Returns the unabridged list of repositories as a json response.

The following headers will be returned with the response:

Name	Description
`Content-Length`	Length of the JSON response body.

Catalog Fetch Paginated

GET /v2/_catalog?n=<integer>&last=<integer>

Return the specified portion of repositories.

The following parameters should be specified on the request:

Name	Kind	Description
`n`	query	Limit the number of entries in each response. It not present, all entries will be returned.
`last`	query	Result set will include values lexically after last.

On Success: OK

200 OK
Content-Length: <length>
Link: <<url>?n=<last n value>&last=<last entry from response>>; rel="next"
Content-Type: application/json; charset=utf-8

{
	"repositories": [
		<name>,
		...
	]
	"next": "<url>?last=<name>&n=<last value of n>"
}

The following headers will be returned with the response:

Name	Description
`Content-Length`	Length of the JSON response body.
`Link`	RFC5988 compliant rel='next' with URL to next result set, if available

100 KiB Raw Blame History

Docker Registry HTTP API V2

Introduction

Scope

Future

Use Cases

Image Verification

Resumable Push

Resumable Pull

Layer Upload De-duplication

Changes

Overview

Errors

API Version Check

Content Digests

Digest Header

Pulling An Image

Pulling an Image Manifest

Pulling a Layer

Pushing An Image

Pushing a Layer

Starting An Upload

Existing Layers

Uploading the Layer

Upload Progress

Monolithic Upload

Chunked Upload

Completed Upload

Digest Parameter

Canceling an Upload

Errors

Deleting a Layer

Pushing an Image Manifest

Listing Repositories

Pagination

Listing Image Tags

Pagination

Deleting an Image

Detail

Errors

Base

GET Base

On Success: OK

On Failure: Unauthorized

On Failure: Not Found

Tags

GET Tags

Tags

On Success: OK

On Failure: Not Found

On Failure: Unauthorized

Tags Paginated

On Success: OK

On Failure: Not Found

On Failure: Unauthorized

Manifest

GET Manifest

On Success: OK

On Failure: Bad Request

On Failure: Unauthorized

On Failure: Not Found

PUT Manifest

On Success: Created

On Failure: Invalid Manifest

On Failure: Unauthorized

On Failure: Missing Layer(s)

On Failure: Unauthorized

DELETE Manifest

On Success: Accepted

On Failure: Invalid Name or Reference

On Failure: Unauthorized

On Failure: Unknown Manifest

Blob

GET Blob

Fetch Blob

On Success: OK

On Success: Temporary Redirect

On Failure: Bad Request

On Failure: Unauthorized

On Failure: Not Found

100 KiB

Raw Blame History