Fix issue where manifest content must always be fetched
even if it is already fully downloaded or shared locally.
Simplify children label setting and platform filtering.
Prevent getting a fetcher when content shared locally.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
- Use lease API (previoisly, GC was not supported)
- Refactored interfaces for ease of future Docker v1 importer support
For usage, please refer to `ctr images import --help`.
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Schema1 manifests did not set a size in the digest for the blobs,
breaking the expectations of the update http seeking reader. Now
the http seeker has been updated to support unknown size as a
value of negative 1 and the schema1 puller sets the unknown size
accordingly.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Currently pushing a new tag to a manifest which already
exists in the registry skips the tag push because it
only checks that the manifest exists. This updates the
logic to instead check if the tag exists and is at the
same digest.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
To support resumable download, the fetcher for a remote must implement
`io.Seeker`. If implemented the `content.Copy` function will detect the
seeker and begin from where the download was terminated by a previous
attempt.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
To allow concurrent pull of images of the v1 persuasion, we need to
backoff when multiple pullers are trying to operate on the same
resource. The back off logic is ported to v1 pull to match the behavior
for other images.
A little randomness is also added to the backoff to prevent thundering
herd and to reduce expected recovery time.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Prevents a server from sending a large response causing containerd to
allocate too much RAM and potentially OOM.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Add support for downloading layers with external URLs and
foreign/non-distributable mediatypes. This ensures that encountered
windows images are downloaded correctly. We still need to filter out the
extra windows resources when pulling linux, but this is a step towards
correctly supporting multi-platform images.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Content commit is updated to take in a context, allowing
content to be committed within the same context the writer
was in. This is useful when commit may be able to use more
context to complete the action rather than creating its own.
An example of this being useful is for the metadata implementation
of content, having a context allows tests to fully create
content in one database transaction by making use of the context.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Support registries returning 204 or 200 in place of 201/202.
Ensure body is closed when request is retried.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Add commit options which allow for setting labels on commit.
Prevents potential race between garbage collector reading labels
after commit and labels getting set.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
After some analysis, it was found that Content.Reader was generally
redudant to an io.ReaderAt. This change removes `Content.Reader` in
favor of a `Content.ReaderAt`. In general, `ReaderAt` can perform better
over interfaces with indeterminant latency because it avoids remote
state for reads. Where a reader is required, a helper is provided to
convert it into an `io.SectionReader`.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Now that we have most of the services required for use with containerd,
it was found that common patterns were used throughout services. By
defining a central `errdefs` package, we ensure that services will map
errors to and from grpc consistently and cleanly. One can decorate an
error with as much context as necessary, using `pkg/errors` and still
have the error mapped correctly via grpc.
We make a few sacrifices. At this point, the common errors we use across
the repository all map directly to grpc error codes. While this seems
positively crazy, it actually works out quite well. The error conditions
that were specific weren't super necessary and the ones that were
necessary now simply have better context information. We lose the
ability to add new codes, but this constraint may not be a bad thing.
Effectively, as long as one uses the errors defined in `errdefs`, the
error class will be mapped correctly across the grpc boundary and
everything will be good. If you don't use those definitions, the error
maps to "unknown" and the error message is preserved.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This PR ensures that we can pull images with manifest lists, aka OCI
indexes. After this change, when pulling such an image, the resources
will all be available for creating the image.
Further support is required to do platform based selection for rootfs
creation, so such images may not yet be runnable. This is mostly useful
for checkpoint transfers, which use an OCI index for assembling the
component set.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
These interfaces allow us to preserve both the checking of error "cause"
as well as messages returned from the gRPC API so that the client gets
full error reason instead of a default "metadata: not found" in the case
of a missing image.
Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>
The size and throwaway fields in the history can bother be
omitted, making the emptiness of a layer ambiguous. In these
cases download and check whether the content is empty.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Updates content service to handle lock errors and return
them to the client. The client remote handler has been
updated to retry when a resource is locked until the
resource is unlocked or the expected resource exists.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Split resolver to only return a name with separate methods
for getting a fetcher and pusher. Add implementation for
push.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Open up content store writer with expected digest before
opening up the fetch call to the registry. Add Copy method
to content store helpers to allow content copy to take
advantage of seeking helper code.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Tests resolving, fetching, and using the various authentication
methods supported by the Docker registry protocol.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Allow usage of the experimental docker resolver as a package. There are
very few changes to the consuming code, demonstrating the effectiveness
of the abstraction. This move will allow future contributions to a more
featured resolver implementation.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
With this PR, we introduce the concept of image handlers. They support
walking a tree of image resource descriptors for doing various tasks
related to processing them. Handlers can be dispatched sequentially or
in parallel and can be stacked for various effects.
The main functionality we introduce here is parameterized fetch without
coupling format resolution to the process itself. Two important
handlers, `remotes.FetchHandler` and `image.ChildrenHandler` can be
composed to implement recursive fetch with full status reporting. The
approach can also be modified to filter based on platform or other
constraints, unlocking a lot of possibilities.
This also includes some light refactoring in the fetch command, in
preparation for submission of end to end pull.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
After receiving feedback during containerd summit walk through of the
pull POC, we found that the resolution flow for names was out of place.
We could see this present in awkward places where we were trying to
re-resolve whether something was a digest or a tag and extra retries to
various endpoints.
By centering this problem around, "what do we write in the metadata
store?", the following interface comes about:
```
Resolve(ctx context.Context, ref string) (name string, desc ocispec.Descriptor, fetcher Fetcher, err error)
```
The above takes an "opaque" reference (we'll get to this later) and
returns the canonical name for the object, a content description of the
object and a `Fetcher` that can be used to retrieve the object and its
child resources. We can write `name` into the metadata store, pointing
at the descriptor. Descisions about discovery, trust, provenance,
distribution are completely abstracted away from the pulling code.
A first response to such a monstrosity is "that is a lot of return
arguments". When we look at the actual, we can see that in practice, the
usage pattern works well, albeit we don't quite demonstrate the utility
of `name`, which will be more apparent later. Designs that allowed
separate resolution of the `Fetcher` and the return of a collected
object were considered. Let's give this a chance before we go
refactoring this further.
With this change, we introduce a reference package with helps for
remotes to decompose "docker-esque" references into consituent
components, without arbitrarily enforcing those opinions on the backend.
Utlimately, the name and the reference used to qualify that name are
completely opaque to containerd. Obviously, implementors will need to
show some candor in following some conventions, but the possibilities
are fairly wide. Structurally, we still maintain the concept of the
locator and object but the interpretation is up to the resolver.
For the most part, the `dist` tool operates exactly the same, except
objects can be fetched with a reference:
```
dist fetch docker.io/library/redis:latest
```
The above should work well with a running containerd instance. I
recommend giving this a try with `fetch-object`, as well. With
`fetch-object`, it is easy for one to better understand the intricacies
of the OCI/Docker image formats.
Ultimately, this serves the main purpose of the elusive "metadata
store".
Signed-off-by: Stephen J Day <stephen.day@docker.com>
After implementing pull, a few changes are required to the content store
interface to make sure that the implementation works smoothly.
Specifically, we work to make sure the predeclaration path for digests
works the same between remote and local writers. Before, we were
hesitent to require the the size and digest up front, but it became
clear that having this provided significant benefit.
There are also several cleanups related to naming. We now call the
expected digest `Expected` consistently across the board and `Total` is
used to mark the expected size.
This whole effort comes together to provide a very smooth status
reporting workflow for image pull and push. This will be more obvious
when the bulk of pull code lands.
There are a few other changes to make `content.WriteBlob` more broadly
useful. In accordance with addition for predeclaring expected size when
getting a `Writer`, `WriteBlob` now supports this fully. It will also
resume downloads if provided an `io.Seeker` or `io.ReaderAt`. Coupled
with the `httpReadSeeker` from `docker/distribution`, we should only be
a lines of code away from resumable downloads.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
With this changeset we introduce several new things. The first is the
top-level dist command. This is a toolkit that implements various
distribution primitives, such as fetching, unpacking and ingesting.
The first component to this is a simple `fetch` command. It is a
low-level command that takes a "remote", identified by a `locator`, and
an object identifier. Keyed by the locator, this tool can identify a
remote implementation to fetch the content and write it back to standard
out. By allowing this to be the unit of pluggability in fetching
content, we can have quite a bit of flexibility in how we retrieve
images.
The current `fetch` implementation provides anonymous access to docker
hub images, through the namespace `docker.io`. As an example, one can
fetch the manifest for `redis` with the following command:
```
$ ./dist fetch docker.io/library/redis latest mediatype:application/vnd.docker.distribution.manifest.v2+json
```
Note that we have provided a mediatype "hint", nudging the fetch
implementation to grab the correct endpoint. We can hash the output of
that to fetch the same content by digest:
```
$ ./dist fetch docker.io/library/redis sha256:$(./dist fetch docker.io/library/redis latest mediatype:application/vnd.docker.distribution.manifest.v2+json | shasum -a256)
```
Note that the hint is now elided, since we have affixed the content to a
particular hash.
If you are not yet entertained, let's bring `jq` and `xargs` into the
mix for maximum fun. The following incantation fetches the same manifest
and downloads all layers into the convenience of `/dev/null`:
```
$ ./dist fetch docker.io/library/redis sha256:a027a470aa2b9b41cc2539847a97b8a14794ebd0a4c7c5d64e390df6bde56c73 | jq -r '.layers[] | .digest' | xargs -n1 -P10 ./dist fetch docker.io/library/redis > /dev/null
```
This is just the beginning. We should be able to centralize
configuration around fetch to implement a number of distribution
methodologies that have been challenging or impossible up to this point.
The `locator`, mentioned earlier, is a schemaless URL that provides a
host and path that can be used to resolve the remote. By dispatching on
this common identifier, we should be able to support almost any protocol
and discovery mechanism imaginable.
When this is more solidified, we can roll these up into higher-level
operations that can be orchestrated through the `dist` tool or via GRPC.
What a time to be alive!
Signed-off-by: Stephen J Day <stephen.day@docker.com>
