This implements a base endpoint that will respond with a 200 OK and an empty
json response. Such an endpoint can be used as to ping the v2 service or as an
endpoint to check authorization status.
This commit locks down the set of http error codes that will be part of the
inital V2 specification, proposed in docker/docker#9015. The naming order has
been slightly changed and there are few tweaks to ensure all conditions are
captured but this will be set the docker core will be impleemnted against.
To support this, the errors have been moved into an api/errors package. A new
type, ErrorDescriptor, has been defined to centralize the code, message and
definitions used with each type. The information therein can be used to
generate documentation and response code mappings (yet to come...).
In addition to the refactoring that came along with this change, several tests
have been added to ensure serialization round trips are reliable. This allows
better support for using these error types on the client and server side. This
is coupled with some tweaks in the client code to fix issues with error
reporting.
Other fixes in the client include moving client-specific errors out of the base
package and ensuring that we have correct parameters for finishing uploads.
Because json.Marshal does compaction on returned results, applications must
directly use SignedManifest.Raw when the marshaled value is required.
Otherwise, the returned manifest will fail signature checks.
Push, pull and delete of manifest files in the registry have been implemented
on top of the storage services. Basic workflows, including reporting of missing
manifests are tested, including various proposed response codes. Common testing
functionality has been collected into shared methods. A test suite may be
emerging but it might better to capture more edge cases (such as resumable
upload, range requests, etc.) before we commit to a full approach.
To support clearer test cases and simpler handler methods, an application aware
urlBuilder has been added. We may want to export the functionality for use in
the client, which could allow us to abstract away from gorilla/mux.
A few error codes have been added to fill in error conditions missing from the
proposal. Some use cases have identified some problems with the approach to
error reporting that requires more work to reconcile. To resolve this, the
mapping of Go errors into error types needs to pulled out of the handlers and
into the application. We also need to move to type-based errors, with rich
information, rather than value-based errors. ErrorHandlers will probably
replace the http.Handlers to make this work correctly.
Unrelated to the above, the "length" parameter has been migrated to "size" for
completing layer uploads. This change should have gone out before but these
diffs ending up being coupled with the parameter name change due to updates to
the layer unit tests.
The http API has its first set of endpoints to implement the core aspects of
fetching and uploading layers. Uploads can be started and completed in a single
chunk and the content can be fetched via tarsum. Most proposed error conditions
should be represented but edge cases likely remain.
In this version, note that the layers are still called layers, even though the
routes are pointing to blobs. This will change with backend refactoring over
the next few weeks.
The unit tests are a bit of a shamble but these need to be carefully written
along with the core specification process. As the the client-server interaction
solidifies, we can port this into a verification suite for registry providers.
