An API client for the V2 Docker Registry API, for Go applications.
import (
"github.com/heroku/docker-registry-client/registry"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/manifest"
"github.com/docker/libtrust"
)url := "https://registry-1.docker.io/"
username := "" // anonymous
password := "" // anonymous
hub, err := registry.New(url, username, password)Creating a registry will also ping it to verify that it supports the registry
API, which may fail. Failures return non-nil err values.
Authentication supports both HTTP Basic authentication and OAuth2 token negotiation.
repositories, err := hub.Repositories()The repositories will be returned as a slice of strings.
Each Docker repository has a set of tags -- named images that can be downloaded.
tags, err := hub.Tags("heroku/cedar")The tags will be returned as a slice of strings.
Each tag has a corresponding manifest, which lists the layers and image configuration for that tag.
manifest, err := hub.Manifest("heroku/cedar", "14")Schema V2
manifest, err := hub.ManifestV2("heroku/cedar", "14")The returned manifest will be a manifest.SignedManifest pointer. For details,
see the github.com/docker/distribution/manifest library.
A manifest is identified by a digest.
digest, err := hub.ManifestDigest("heroku/cedar", "14")The returned digest will be a digest.Digest. See github.com/docker/distribution/digest.
To delete a manifest
digest, err := hub.ManifestDigest("heroku/cedar", "14")
err = hub.DeleteManifest("heroku/cedar", digest)Please notice that, as specified by the Registry v2 API, this call doesn't actually remove the fs layers used by the image.
Each manifest contains a list of layers, filesystem images that Docker will compose to create containers.
// or obtain the digest from an existing manifest's FSLayer list
digest := digest.NewDigestFromHex(
"sha256",
"a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4",
)
reader, err := hub.DownloadBlob("heroku/cedar", digest)
if reader != nil {
defer reader.Close()
}
if err != nil {
return err
}This library can also publish new layers:
digest := digest.NewDigestFromHex(
"sha256",
"a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4",
)
exists, err := hub.HasBlob("example/repo", digest)
if err != nil {
// …
}
if !exists {
stream := …
hub.UploadBlob("example/repo", digest, stream)
}First, create a signed manifest:
manifest := &manifest.Manifest{
Versioned: manifest.Versioned{
SchemaVersion: 1,
},
Tag: "latest",
// …
}
key, err := libtrust.GenerateECP256PrivateKey()
if err != nil {
// …
}
signedManifest := manifest.Sign(manifest, key)
if err != nil {
// …
}Production applications should probably reuse keys, rather than generating ephemeral keys. See the libtrust documentation for details.
Then, upload the signed manifest:
err := hub.PutManifest("example/repo", "latest", signedManifest)
if err != nil {
// …
}This will also create or update tags, as necessary.