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build: refactor reference parsing for oci image layouts #1456

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merged 2 commits into from
Jan 6, 2023
Merged

build: refactor reference parsing for oci image layouts #1456

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70682b0
build: refactor reference parsing for image layouts
jedevc Dec 6, 2022
1885e41
docs: update oci layout with tag resolution
jedevc Jan 5, 2023
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54 changes: 45 additions & 9 deletions build/build.go
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ import (
"fmt"
"io"
"os"
"path"
"path/filepath"
"strconv"
"strings"
Expand All @@ -36,8 +37,10 @@ import (
"github.com/docker/docker/pkg/jsonmessage"
"github.com/moby/buildkit/client"
"github.com/moby/buildkit/client/llb"
"github.com/moby/buildkit/client/ociindex"
"github.com/moby/buildkit/exporter/containerimage/exptypes"
gateway "github.com/moby/buildkit/frontend/gateway/client"
"github.com/moby/buildkit/identity"
"github.com/moby/buildkit/session"
"github.com/moby/buildkit/session/upload/uploadprovider"
"github.com/moby/buildkit/solver/errdefs"
Expand Down Expand Up @@ -1478,26 +1481,59 @@ func LoadInputs(ctx context.Context, d driver.Driver, inp Inputs, pw progress.Wr
// handle OCI layout
if strings.HasPrefix(v.Path, "oci-layout://") {
pathAlone := strings.TrimPrefix(v.Path, "oci-layout://")
parts := strings.SplitN(pathAlone, "@", 2)
if len(parts) != 2 {
return nil, errors.Errorf("invalid oci-layout context %s, must be oci-layout:///path/to/layout@sha256:hash", v.Path)
localPath := pathAlone
localPath, dig, hasDigest := strings.Cut(localPath, "@")
localPath, tag, hasTag := strings.Cut(localPath, ":")
if !hasDigest {
indexPath := path.Join(localPath, "index.json")
index, err := ociindex.ReadIndexJSONFileLocked(indexPath)
if err != nil {
return nil, errors.Wrapf(err, "failed to read oci-layout index at %s", indexPath)
}

if len(index.Manifests) == 1 {
dig = string(index.Manifests[0].Digest)
hasDigest = true
}

if !hasTag {
tag = "latest"
}
for _, m := range index.Manifests {
if m.Annotations[specs.AnnotationRefName] == tag {
dig = string(m.Digest)
hasDigest = true
break
}
}
}
if !hasDigest {
return nil, errors.Errorf("oci-layout reference %q could not be resolved", v.Path)
}
localPath := parts[0]
dgst, err := digest.Parse(parts[1])
_, err := digest.Parse(dig)
if err != nil {
return nil, errors.Wrapf(err, "invalid oci-layout context %s, does not have proper hash, must be oci-layout:///path/to/layout@sha256:hash", v.Path)
return nil, errors.Wrapf(err, "invalid oci-layout digest %s", dig)
}

store, err := local.NewStore(localPath)
if err != nil {
return nil, errors.Wrapf(err, "invalid store at %s", localPath)
}
// now we can add it
storeName := identity.NewID()
if target.OCIStores == nil {
target.OCIStores = map[string]content.Store{}
}
target.OCIStores[k] = store
target.OCIStores[storeName] = store

layout := "oci-layout://" + storeName
if hasTag {
layout += ":" + tag
}
if hasDigest {
layout += "@" + dig
}

target.FrontendAttrs["context:"+k] = fmt.Sprintf("oci-layout:%s@%s", k, dgst.String())
target.FrontendAttrs["context:"+k] = layout
continue
}
st, err := os.Stat(v.Path)
Expand Down
16 changes: 6 additions & 10 deletions docs/reference/buildx_build.md
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Original file line number Diff line number Diff line change
Expand Up @@ -136,10 +136,12 @@ COPY --from=project myfile /

#### <a name="source-oci-layout"></a> Source image from OCI layout directory

Source an image from a local [OCI layout compliant directory](https://github.com/opencontainers/image-spec/blob/main/image-layout.md):
Source an image from a local [OCI layout compliant directory](https://github.com/opencontainers/image-spec/blob/main/image-layout.md),
either by tag, or by digest:

```console
$ docker buildx build --build-context foo=oci-layout:///path/to/local/layout@sha256:abcd12345 .
$ docker buildx build --build-context foo=oci-layout:///path/to/local/layout:<tag>
$ docker buildx build --build-context foo=oci-layout:///path/to/local/layout@sha256:<digest>
```

```dockerfile
Expand All @@ -151,14 +153,8 @@ COPY --from=foo myfile /
FROM foo
```

The OCI layout directory must be compliant with the [OCI layout specification](https://github.com/opencontainers/image-spec/blob/main/image-layout.md). It looks _solely_ for hashes. It does not
do any form of `image:tag` resolution to find the hash of the manifest; that is up to you.

The format of the `--build-context` must be: `<context>=oci-layout://<path-to-local-layout>@sha256:<hash-of-manifest>`, where:

* `context` is the name of the build context as used in the `Dockerfile`.
* `path-to-local-layout` is the path on the local machine, where you are running `docker build`, to the spec-compliant OCI layout.
* `hash-of-manifest` is the hash of the manifest for the image. It can be a single-architecture manifest or a multi-architecture index.
The OCI layout directory must be compliant with the [OCI layout specification](https://github.com/opencontainers/image-spec/blob/main/image-layout.md).
You can reference an image in the layout using either tags, or the exact digest.

### <a name="builder"></a> Override the configured builder instance (--builder)

Expand Down