Commit graph

251 commits

Author SHA1 Message Date
Sylvain Baubeau
ef4ab7a885 Use bulk delete to remove segments in Swift driver
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-12-04 12:16:49 +01:00
Stephen Day
4cf93714f3 Merge pull request #1231 from tonistiigi/digest-length-check
Validate digest length on parsing
2015-12-03 12:17:16 -08:00
Stephen Day
d46b6a8796 Merge pull request #1211 from tt/remove-name-verification
Remove name verification
2015-12-03 11:59:21 -08:00
Tonis Tiigi
f015982f0f Validate digest length on parsing
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
2015-12-02 16:04:06 -08:00
Stephen J Day
8aa3ee6923 storage: add further tests for Walk implementation
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-12-01 16:55:10 -08:00
Stephen J Day
5d576bc0cd storage: enforce sorted traversal during Walk
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-12-01 16:25:30 -08:00
Stephen J Day
6ad10796ef storage: correctly handle error during Walk
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-12-01 16:25:29 -08:00
Troels Thomsen
1ece510198 Use well-known error type
Signed-off-by: Troels Thomsen <troels@thomsen.io>
2015-12-01 22:23:47 +01:00
Troels Thomsen
d309bce2d1 Verify manifest name format
Signed-off-by: Troels Thomsen <troels@thomsen.io>
2015-11-26 10:28:35 +01:00
Troels Thomsen
34c8194c95 Verify manifest name length
Signed-off-by: Troels Thomsen <troels@thomsen.io>
2015-11-26 10:28:28 +01:00
Troels Thomsen
e8f8f4034e Remove name verification
Signed-off-by: Troels Thomsen <troels@thomsen.io>
2015-11-25 21:16:28 +01:00
Troels Thomsen
ca9f0451a6 Use case of type name
Signed-off-by: Troels Thomsen <troels@thomsen.io>
2015-11-25 21:12:49 +01:00
Richard Scothern
a33095af80 Merge pull request #1141 from lebauce/swift-no-missing-segment
Ensure read after write for segments
2015-11-10 10:39:43 -08:00
Aaron Lehmann
6664a1384e Fix empty delete requests with Swift fs driver
The Delete method lists objects under the given path and tries to delete
all of them with a bulk delete request. If the path has no objects
underneath it, the body of this request will be empty, which causes
HTTP-level issues. Specifically, Go's HTTP client senses the empty
request buffer and doesn't include a Content-Length, which causes the
Swift server to fail the request.

This commit fixes the problem by avoiding sending empty bulk delete
requests. This is the correct thing to do anyway, since there's no
reason to request deletion of zero objects.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2015-11-09 15:33:05 -08:00
Richard Scothern
362ae9cc41 Merge pull request #1156 from RichardScothern/manifest-verification
Manifest Verification
2015-11-04 14:09:12 -08:00
Richard Scothern
dd32fbe615 Before allowing a schema1 manifest to be stored in the registry, ensure that it
contains equal length History and FSLayer arrays.

This is required to prevent malformed manifests being put to the registry and
failing external verification checks.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
2015-11-03 15:19:46 -08:00
Richard Scothern
bc6e4cdceb Add a generic error type to capture non-typed errors
Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
2015-11-03 11:19:44 -08:00
amitshukla
9637cb40cd Fix for issue 664: https://github.com/docker/distribution/issues/664
Errors thrown by storage drivers don't have the name of the driver, causing user
confusion about whether the error is coming from Docker or from a storage driver.
This change adds the storage driver name to each error message.

This required changing ErrUnsupportedDriver to a type, leading to code changes
whenever ErrUnsupportedDriver is used.  The tests check whether the driver name
appears in the error message.

Signed-off-by: Amit Shukla <amit.shukla@docker.com>
2015-11-03 11:19:17 -08:00
Richard Scothern
a9da0e5100 Merge pull request #1114 from lebauce/swift-temp-url
Redirect support in Swift driver
2015-11-03 09:34:01 -08:00
Sylvain Baubeau
3ff8af326b Ensure read after write for segments
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-11-03 17:09:52 +01:00
Sylvain Baubeau
7c3281861f Add support for temporary URL for Swift driver
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-11-03 09:59:50 +01:00
Stephen J Day
46dd057f5c registry/storage: close filereader after allocation
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-11-02 11:55:11 -08:00
Arthur Baars
59784ecdd0 Storage driver for: Google Cloud Storage (gcs)
Signed-off-by: Arthur Baars <arthur@semmle.com>
2015-10-28 20:21:56 +00:00
Stephen Day
e5d9837970 Merge pull request #1098 from denverdino/master
Redundant digest verification in validateBlob when pushing a new layer
2015-10-21 14:50:18 -07:00
Aaron Lehmann
5608db616c Correct two golint comment issues
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2015-10-19 16:42:12 -07:00
Li Yi
ad14545745 Redundant digest verification in validateBlob
Change-Id: I03764edadae529db2cc3acf7ecca329570f18659
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-10-15 22:21:14 +08:00
Derek McGowan
31a448a628 Update to provide small and clear interfaces
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
2015-10-09 16:05:49 -07:00
Tibor Vass
f8c09b6a7d Add a new reference package abstracting repositories, tags and digests
There seems to be a need for a type that represents a way of pointing
to an image, irrespective of the implementation.

This patch defines a Reference interface and provides 3 implementations:
- TagReference: when only a tag is provided
- DigestReference: when a digest (according to the digest package) is
  provided, can include optional tag as well

Validation of references are purely syntactic.

There is also a strong type for tags, analogous to digests, as well
as a strong type for Repository from which clients can access the
hostname alone, or the repository name without the hostname, or both
together via the String() method.

For Repository, the files names.go and names_test.go were moved from
the v2 package.

Signed-off-by: Tibor Vass <tibor@docker.com>
2015-10-09 16:05:34 -07:00
Richard Scothern
61a4a1362c Merge pull request #950 from jackpgriffin/master
Skip creating swift container if already exists
2015-10-01 10:15:54 -07:00
Stephen Day
ca2156d558 Merge pull request #1024 from aaronlehmann/avoid-testing-import
Avoid importing "testing" in externally-facing code
2015-09-30 13:14:42 +02:00
Aaron Lehmann
6acb3a0d7e Avoid importing "testing" in externally-facing code
The "testing" package adds some flags in its init function, so utilities
that import distribution code may print a page of extra testing flags in
their help output.

This commit solves the issue by moving an import of "testing" in the
registry/storage/cache package to a new
registry/storage/cache/cachecheck package, which is only imported by
tests.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2015-09-29 10:06:39 -07:00
Nuutti Kotivuori
26d8344872 Remove initial access check from S3 driver
In the S3 storage driver there is currently an initial access permission check by listing the bucket. If this check fails, registry will panic and exit.

However, this check is broken in two ways. First of all it strips the final slash from the root directory path, meaning that any access permissions which limit access to a single directory will fail, because S3 treats the path as strict prefix match. Secondly it fails to strip any leading slash that might be present, unlike the other access places, which means that the path used is different as a leading slash is allowed and significant in a filename in S3.

Since there is also a periodic health check which correctly checks access permissions and shows the error more cleanly, the best solution seems to be to just remove this initial access check.

Signed-off-by: Nuutti Kotivuori <nuutti.kotivuori@poplatek.fi>
2015-09-19 12:47:12 +03:00
Stephen J Day
360c24d975 Allow interface{} keys when using logger
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-09-11 11:33:55 -07:00
Jack Griffin
2749bcdc28 Skip creating swift container if already exists
Signed-off-by: Jack Griffin <jackpg14@gmail.com>
2015-09-04 18:53:17 +00:00
Hua Wang
ddb689ef8b Add TrustId parameter to swift driver
github/ncw/swift has added support for trust, so let's add it.

Signed-off-by: Hua Wang <wanghua.humble@gmail.com>
2015-09-02 15:05:29 +08:00
Stephen J Day
6712e602b0 Move manifest package to schema1
As we begin our march towards multi-arch, we must prepare for the reality of
multiple manifest schemas. This is the beginning of a set of changes to
facilitate this. We are both moving this package into its target position where
it may live peacefully next to other manfiest versions.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-08-21 16:29:47 -07:00
Aaron Lehmann
dbbcf5fe42 Functional options for NewRegistryWithDriver
Clean up calling convention for NewRegistryWithDriver to use functional
arguments.

This is a first step towards the refactor described in #215. I plan to
add additional options in the process of moving configurable items from
the App structure to the registry structure.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2015-08-19 11:06:30 -07:00
Stephen J Day
641cdf3ba6 Remove pathMapper object
The use of the pathMapper is no longer needed the way we have organized the
code base. The extra level of indirection has proved unnecessary and confusing
so we've opted to clean it up. In the future, we may require more flexibility,
but now it is simply not required.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-08-17 18:51:05 -07:00
Stephen J Day
06a098c632 Maintain manifest link compatibility
Unfortunately, the 2.1 releease has written manfiest links into the wrong
directory. This doesn't affect new 2.1 deployments but fixing this to be 2.0
backwards compatible has broken 2.1.0 compatibility. To ensure we have
compatibility between 2.0, 2.1.0 and future releases, we now check one of
several locations to identify a manifest link.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-08-12 13:11:13 -07:00
Stephen J Day
d00586de9f Use correct path for manifest revision path
Unfortunately, the refactor used the incorrect path for manifest links within a
repository. While this didn't stop the registry from working, it did break
compatibility with 2.0 deployments for manifest fetches.

Tests were added to ensure these are locked down to the appropriate paths.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-08-12 13:10:15 -07:00
Vincent Giersch
6c39af6708 fix(rados): Create OMAP for root directory
When using the RADOS driver, the hierarchy of the files is stored
in OMAPs, but the root OMAP was not created and a call to List("/")
was returning an error instead of returned the first level files
stored. This patches creates an OMAP for "/" and excludes the listed
directory from the list of files returned.

Signed-off-by: Vincent Giersch <vincent@giersch.fr>
2015-08-10 23:46:33 +02:00
Stephen Day
a0c63372fa Merge pull request #779 from RichardScothern/pull-through-cache
Add pull through cache ability to the Registry.
2015-08-04 17:04:56 -07:00
Richard Scothern
94935f39bc Add pull through cache functionality to the Registry which can be configured
with a new `proxy` section in the configuration file.

Create a new registry type which delegates storage to a proxyBlobStore
and proxyManifestStore.  These stores will pull through data if not present
locally.  proxyBlobStore takes care not to write duplicate data to disk.

Add a scheduler to cleanup expired content. The scheduler runs as a background
goroutine.  When a blob or manifest is pulled through from the remote registry,
an entry is added to the scheduler with a TTL.  When the TTL expires the
scheduler calls a pre-specified function to remove the fetched resource.

Add token authentication to the registry middleware.  Get a token at startup
and preload the credential store with the username and password supplied in the
config file.

Allow resumable digest functionality to be disabled at runtime and disable
it when the registry is a pull through cache.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
2015-08-04 16:09:55 -07:00
Aaron Lehmann
3a414deddb Merge pull request #514 from denverdino/master
Storage Driver for Aliyun OSS
2015-08-04 12:01:02 -07:00
Doug Davis
633eec0f91 Fix vet issue
registry/storage/blob_test.go:149: arg d for printf verb %s of wrong type: github.com/docker/distribution.Descriptor

Signed-off-by: Doug Davis <dug@us.ibm.com>
2015-08-03 12:24:34 -07:00
tgic
72c794a810 remove unused code and fix todo format
Signed-off-by: tgic <farmer1992@gmail.com>
2015-07-31 13:22:56 +08:00
tgic
e53d99a837 fix goimports
Signed-off-by: tgic <farmer1992@gmail.com>
2015-07-31 13:22:56 +08:00
tgic
0058b08eeb add include_oss build tag
Signed-off-by: tgic <farmer1992@gmail.com>
2015-07-31 13:22:56 +08:00
Li Yi
708ad28114 Update the comment for the consistency model
Change-Id: Iee49afeda1c11d6af8c0f26c96d8ccc328c22757
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:55 +08:00
Li Yi
539c7f5311 Update the comments for consistence model
Change-Id: I161522ee51f247fb17e42844b3699bd9031e34e8
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:55 +08:00
tgic
8e5c901a26 fix testcase TestReadStreamWithOffset incompatible with oss
Signed-off-by: tgic <farmer1992@gmail.com>
2015-07-31 13:22:55 +08:00
tgic
2a8535626f fix oss: got 403 in TestContinueStreamAppendLarge
Signed-off-by: tgic <farmer1992@gmail.com>
2015-07-31 13:22:55 +08:00
Li Yi
813543d6e3 Update the OSS test case for latest code change
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:55 +08:00
tgic
3a240de22e check access key and secret before run 2015-07-31 13:22:55 +08:00
tgic
3d30cb38f6 add endpoint support 2015-07-31 13:22:54 +08:00
Li Yi
c3b42db014 Add the secure access with HTTPS
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:54 +08:00
Li Yi
b8a276f2db Fix the warning of golint
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:54 +08:00
Li Yi
9e4975d8ff Support OSS driver
Signed-off-by: Li Yi <denverdino@gmail.com>
2015-07-31 13:22:54 +08:00
Stephen J Day
9f9a7f230b Allow disabling of starage driver redirects
Storage drivers can implement a method called URLFor which can return a direct
url for a given path. The functionality allows the registry to direct clients
to download content directly from the backend storage. This is commonly used
with s3 and cloudfront. Under certain conditions, such as when the registry is
not local to the backend, these redirects can hurt performance and waste
incoming bandwidth on pulls. This feature addition allows one to disable this
feature, if required.

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

Conflicts:
	configuration/configuration.go
	registry/handlers/app.go
	registry/storage/catalog_test.go
	registry/storage/manifeststore_test.go
	registry/storage/registry.go
2015-07-24 16:59:35 -07:00
Stephen Day
b49d77a42f Merge pull request #739 from stevvooe/etags-must-be-quoted
Etags must be quoted according to http spec
2015-07-24 15:08:27 -07:00
Stephen J Day
338e645f20 Etags must be quoted according to http spec
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-07-24 13:07:38 -07:00
Richard
9c1dd69439 Manifest and layer soft deletion.
Implement the delete API by implementing soft delete for layers
and blobs by removing link files and updating the blob descriptor
cache.  Deletion is configurable - if it is disabled API calls
will return an unsupported error.

We invalidate the blob descriptor cache by changing the linkedBlobStore's
blobStatter to a blobDescriptorService and naming it blobAccessController.

Delete() is added throughout the relevant API to support this functionality.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
2015-07-24 09:57:20 -07:00
Stephen Day
34e5b1849c Merge pull request #493 from nevermosby/storage-support-openstack-swift
Storage support openstack swift
2015-07-22 23:53:36 -07:00
Stephen Day
76f29c2630 Merge pull request #653 from pdevine/catalog-api
Catalog for V2 API Implementation
2015-07-22 18:54:48 -07:00
Stephen Day
e04ea232b5 Merge pull request #709 from hopkings2008/master
Close reader after the test is finished.
2015-07-22 12:22:22 -07:00
Patrick Devine
b7e26bac74 Create Repositories method
This change removes the Catalog Service and replaces it with a more
simplistic Repositories() method for obtaining a catalog of all
repositories.  The Repositories method takes a pre-allocated slice
and fills it up to the size of the slice and returns the amount
filled.  The catalog is returned lexicographically and will start
being filled from the last entry passed to Repositories().  If there
are no more entries to fill, io.EOF will be returned.

Signed-off-by: Patrick Devine <patrick.devine@docker.com>

Conflicts:
	registry/client/repository.go
	registry/handlers/api_test.go
2015-07-21 21:45:14 -07:00
Patrick Devine
74563efe98 Catalog for V2 API Implementation
This change adds a basic catalog endpoint to the API, which returns a list,
or partial list, of all of the repositories contained in the registry.  Calls
to this endpoint are somewhat expensive, as every call requires walking a
large part of the registry.

Instead, to maintain a list of repositories, you would first call the catalog
endpoint to get an initial list, and then use the events API to maintain
any future repositories.

Signed-off-by: Patrick Devine <patrick.devine@docker.com>
2015-07-21 21:45:14 -07:00
davidli
d1b4bae078 Remove IPC support from test file
Signed-off-by: Li Wenquan <wenquan.li@hp.com>
2015-07-21 23:55:10 +02:00
Sylvain Baubeau
cca15a76f1 Catch either missing containers or objects
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:10 +02:00
Sylvain Baubeau
b4cf6c053b Do not use Swift server side copy for manifests to handle >5G files
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:10 +02:00
Sylvain Baubeau
326c3a9c49 Inline Swift errors handling
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:10 +02:00
Sylvain Baubeau
15d567671b Retrieve all the objects using pagination
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
49582a6188 Do not create objects for directories
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
ed08d8d4e0 Refactor segment path concatenation code
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
91e17e10cd Use http.StatusRequestedRangeNotSatisfiable instead of error code
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
f4ca709d70 Use file instead of filepath as it may cause troubles on Windows
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
78d722e708 Protect against deletion of objects with the same prefix
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
61e3bce794 Show distribution version in User-Agent
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
f256797cac Do not use suite style testing for Swift specific tests
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
53e80944f1 Rename environment variables to run Swift testsuite
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
d0dd36125c Check file has been opened before closing it
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
1a80ec340b Rename DriverParameters structure to Parameters
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
2846913552 Change folder mime type to application/vnc.swift.directory
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
33028c11a7 Add code documentation
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
f21cbcebc6 Do not read segment if no padding is necessary
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
3242378e1b Improve 404 errors handling
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
57cef57e1b Use only one Swift container for both files and manifests
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
a40502ec02 Increase default chunk size to 20M
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
davidli
af99dbd6bf Add support for Openstack Identity v3 API
Signed-off-by: Li Wenquan <wenquan.li@hp.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
3fb42a1502 Use 'prefix' parameter instead of 'path' when listing files
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
1c01ca4b39 Create full folder hierarchy instead of just the top level folder
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
c4d845cb6c Remove one level of indentation in swift path handling code
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
4497d6c973 Use mitchellh/mapstructure library to parse Swift parameters
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
2632fd9dc8 Move Dynamic Large Object handling to dedicated methods
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
d8d50fb0e0 Simplify code that handles non existing manifests
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
5e650a820a Handle error during copy of original content
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:09 +02:00
nevermosby
7372c13f29 Update the import path for swift driver test
Signed-off-by: Li Wenquan <wenquan.li@hp.com>
2015-07-21 23:55:09 +02:00
davidli
6dc1596be4 Use gofmt to format the code of swift driver.
Signed-off-by: Li Wenquan <wenquan.li@hp.com>
2015-07-21 23:55:09 +02:00
Sylvain Baubeau
ea7c53df08 Add Openstack Swift storage driver
Signed-off-by: Sylvain Baubeau <sbaubeau@redhat.com>
2015-07-21 23:55:08 +02:00
Stephen J Day
26b7fe4a91 Use "Size" field to describe blobs over "Length"
After consideration, we've changed the main descriptor field name to for number
of bytes to "size" to match convention. While this may be a subjective
argument, commonly we refer to files by their "size" rather than their
"length". This will match other conventions, like `(FileInfo).Size()` and
methods on `io.SizeReaderAt`. Under more broad analysis, this argument doesn't
necessarily hold up. If anything, "size" is shorter than "length".

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-07-17 17:07:11 -07:00