We are change the the rpc call for WriteStream to not require the size
argument, opting to drive the process with io.Reader. The main issue was that
io.Reader may return io.EOF before reaching size, making the error handling
around this condition for callers more complex. To complement this, WriteStream
now returns the number of successfully written bytes.
The method no longer requires an io.ReadCloser, opting to require just an
io.Reader. This keeps the reader under the control of the caller, which
provides more flexibility.
This also begins to address some of the problems described in #791.
To support single-flight Size and ModTime queries against backend storage file,
we are replacing the CurrentSize call with a Stat call. A FileInfo interface is
provided for backends to provide a type, with a default implementation called
FileInfoInternal, for use by driver implementations.
More work needs to follow this change to update all the driver implementations.
This change brings the storagedriver API in line with the Go standard library's
use of int64 for offsets. The main benefit is simplicity in interfacing with
the io library reducing the number of type conversions in simple code.
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.
This diff removes a few early outs that caused errors to be unreported and
catches a missed error case for signature verification from libtrust. More work
needs to be done around ensuring consistent error handling but this is enough
to make the API work correctly.
This provides compatibility with what is in docker core, ensuring that image
manifests generated here have the same formatting. We'll need to automate this
some how.
Without this copy, the buffer may be re-used in the json package, causing
missing or corrupted content for the long-lived SignedManifest object. By
creating a new buffer, owned by the SignedManifest object, the content remains
stable.
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.
To provide rich error reporting during manifest pushes, the storage layers
verifyManifest stage has been modified to provide the necessary granularity.
Along with this comes with a partial shift to explicit error types, which
represents a small move in larger refactoring of error handling. Signature
methods from libtrust have been added to the various Manifest types to clean up
the verification code.
A primitive deletion implementation for manifests has been added. It only
deletes the manifest file and doesn't attempt to add some of the richer
features request, such as layer cleanup.
Previously, discussions were still ongoing about different storage layouts that
could support various access models. This changeset removes a layer of
indirection that was in place due to earlier designs. Effectively, this both
associates a layer with a named repository and ensures that content cannot be
accessed across repositories. It also moves to rely on tarsum as a true
content-addressable identifier, removing a layer of indirection during blob
resolution.
This change implements the first pass at image manifest storage on top of the
storagedriver. Very similar to LayerService, its much simpler due to less
complexity of pushing and pulling images.
Various components are still missing, such as detailed error reporting on
missing layers during verification, but the base functionality is present.
This changeset move the Manifest type into the storage package to make the type
accessible to client and registry without import cycles. The structure of the
manifest was also changed to accuratle reflect the stages of the signing
process. A straw man Manifest.Sign method has been added to start testing this
concept out but will probably be accompanied by the more import
SignedManifest.Verify method as the security model develops.
This is probably the start of a concerted effort to consolidate types across
the client and server portions of the code base but we may want to see how such
a handy type, like the Manifest and SignedManifest, would work in docker core.
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.
This updates API error codes to coincide with changes to the proposal. Mostly,
redundant error codes were merged and missing ones were added. The set in the
main errors.go file will flow back into the specification.
A test case has been added to ensure ErrorCodeUnknown is included in marshaled
json.
This change separates out the remote file reader functionality from layer
reprsentation data. More importantly, issues with seeking have been fixed and
thoroughly tested.
Stephen J Day