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Rewrite registry client to use docker distribution
The package github.com/docker/distribution/registry/client (now) has types and procedures for fetching image metadata. This means we can get rid of a lot of the workarounds we were using to patch `docker-registry-client` so that e.g., it works with quay.io. I have changed the interfaces around a bit, since we usually need to request image manifests "in a straight line", reusing the same authorisation, and it makes sense to construct a client for each such series of requests. There are a few things we can keep track of across series of requests: specifically, the challenges we've seen from each host. So it's still useful to have a "factory" to hold that information, as well as other commonalities like rate limiting.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,100 +1,139 @@ | ||
| package registry | ||
|
|
||
| import ( | ||
| "context" | ||
| "encoding/json" | ||
| "fmt" | ||
| "errors" | ||
| "net/http" | ||
| "net/url" | ||
| "time" | ||
|
|
||
| dockerregistry "github.com/heroku/docker-registry-client/registry" | ||
| "github.com/pkg/errors" | ||
| "github.com/docker/distribution" | ||
| "github.com/docker/distribution/manifest/manifestlist" | ||
| "github.com/docker/distribution/manifest/schema1" | ||
| "github.com/docker/distribution/manifest/schema2" | ||
| "github.com/docker/distribution/registry/client" | ||
| "github.com/opencontainers/go-digest" | ||
|
|
||
| "github.com/weaveworks/flux/image" | ||
| ) | ||
|
|
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| // An implementation of Client that represents a Remote registry. | ||
| // E.g. docker hub. | ||
| type Remote struct { | ||
| Registry *dockerregistry.Registry | ||
| transport http.RoundTripper | ||
| repo image.CanonicalName | ||
| } | ||
|
|
||
| // Return the tags for this repository. | ||
| func (a *Remote) Tags(id image.Name) ([]string, error) { | ||
| return a.Registry.Tags(id.Repository()) | ||
| // Adapt to docker distribution reference.Named | ||
| type named struct { | ||
| image.CanonicalName | ||
| } | ||
|
|
||
| func (n named) Name() string { | ||
| return n.Image | ||
| } | ||
|
|
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| func (n named) String() string { | ||
| return n.String() | ||
| } | ||
|
|
||
| // We need to do some adapting here to convert from the return values | ||
| // from dockerregistry to our domain types. | ||
| func (a *Remote) Manifest(id image.Ref) (image.Info, error) { | ||
| manifestV2, err := a.Registry.ManifestV2(id.Repository(), id.Tag) | ||
| // Return the tags for this repository. | ||
| func (a *Remote) Tags() ([]string, error) { | ||
| ctx := context.TODO() | ||
| repository, err := client.NewRepository(named{a.repo}, "https://"+a.repo.Domain, a.transport) | ||
| if err != nil { | ||
| if err, ok := err.(*url.Error); ok { | ||
| if err, ok := (err.Err).(*dockerregistry.HttpStatusError); ok { | ||
| if err.Response.StatusCode == http.StatusNotFound { | ||
| return a.ManifestFromV1(id) | ||
| } | ||
| } | ||
| } | ||
| return image.Info{}, err | ||
| } | ||
| // The above request will happily return a bogus, empty manifest | ||
| // if handed something other than a schema2 manifest. | ||
| if manifestV2.Config.Digest == "" { | ||
| return a.ManifestFromV1(id) | ||
| return nil, err | ||
| } | ||
| return repository.Tags(ctx).All(ctx) | ||
| } | ||
|
|
||
| // schema2 manifests have a reference to a blog that contains the | ||
| // image config. We have to fetch that in order to get the created | ||
| // datetime. | ||
| conf := manifestV2.Config | ||
| reader, err := a.Registry.DownloadLayer(id.Repository(), conf.Digest) | ||
| // Manifest fetches the metadata for an image reference; currently | ||
| // assumed to be in the same repo as that provided to `NewRemote(...)` | ||
| func (a *Remote) Manifest(ref string) (image.Info, error) { | ||
| ctx := context.TODO() | ||
| repository, err := client.NewRepository(named{a.repo}, "https://"+a.repo.Domain, a.transport) | ||
| if err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| if reader == nil { | ||
| return image.Info{}, fmt.Errorf("nil reader from DownloadLayer") | ||
| manifests, err := repository.Manifests(ctx) | ||
| if err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| manifest, fetchErr := manifests.Get(ctx, digest.Digest(ref), distribution.WithTagOption{ref}) | ||
|
|
||
| type config struct { | ||
| Created time.Time `json:created` | ||
| interpret: | ||
| if fetchErr != nil { | ||
| return image.Info{}, err | ||
| } | ||
| var imageConf config | ||
|
|
||
| err = json.NewDecoder(reader).Decode(&imageConf) | ||
| mt, bytes, err := manifest.Payload() | ||
| if err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| return image.Info{ | ||
| ID: id, | ||
| CreatedAt: imageConf.Created, | ||
| }, nil | ||
| } | ||
|
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||
| func (a *Remote) ManifestFromV1(id image.Ref) (image.Info, error) { | ||
| manifest, err := a.Registry.Manifest(id.Repository(), id.Tag) | ||
| if err != nil || manifest == nil { | ||
| return image.Info{}, errors.Wrap(err, "getting remote manifest") | ||
| } | ||
| info := image.Info{ID: a.repo.ToRef(ref)} | ||
|
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||
| // the manifest includes some v1-backwards-compatibility data, | ||
| // oddly called "History", which are layer metadata as JSON | ||
| // strings; these appear most-recent (i.e., topmost layer) first, | ||
| // so happily we can just decode the first entry to get a created | ||
| // time. | ||
| type v1image struct { | ||
| // for decoding the v1-compatibility entry in schema1 manifests | ||
| var v1 struct { | ||
| ID string `json:"id"` | ||
| Created time.Time `json:"created"` | ||
| OS string `json:"os"` | ||
| Arch string `json:"architecture"` | ||
| } | ||
| var topmost v1image | ||
| var img image.Info | ||
| img.ID = id | ||
| if len(manifest.History) > 0 { | ||
| if err = json.Unmarshal([]byte(manifest.History[0].V1Compatibility), &topmost); err == nil { | ||
| if !topmost.Created.IsZero() { | ||
| img.CreatedAt = topmost.Created | ||
|
|
||
| // TODO(michael): can we type switch? Not sure how dependable the | ||
| // underlying types are. | ||
| switch mt { | ||
| case schema1.MediaTypeManifest: | ||
| // TODO: can this be fallthrough? Find something to check on... | ||
| var man schema1.Manifest | ||
| if err = json.Unmarshal(bytes, &man); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| if err = json.Unmarshal([]byte(man.History[0].V1Compatibility), &v1); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| info.CreatedAt = v1.Created | ||
| case schema1.MediaTypeSignedManifest: | ||
| var man schema1.SignedManifest | ||
| if err = json.Unmarshal(bytes, &man); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| if err = json.Unmarshal([]byte(man.History[0].V1Compatibility), &v1); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| info.CreatedAt = v1.Created | ||
| case schema2.MediaTypeManifest: | ||
| var man schema2.Manifest | ||
| if err = json.Unmarshal(bytes, &man); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
|
|
||
| configBytes, err := repository.Blobs(ctx).Get(ctx, man.Config.Digest) | ||
| if err != nil { | ||
| return image.Info{}, err | ||
| } | ||
|
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||
| var config struct { | ||
| Arch string `json:"architecture"` | ||
| Created time.Time `json:"created"` | ||
| OS string `json:"os"` | ||
| } | ||
| if err = json.Unmarshal(configBytes, &config); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| info.CreatedAt = config.Created | ||
| case manifestlist.MediaTypeManifestList: | ||
| var list manifestlist.ManifestList | ||
| if err = json.Unmarshal(bytes, &list); err != nil { | ||
| return image.Info{}, err | ||
| } | ||
| // TODO(michael): can we just pick the first one that matches? | ||
| for _, m := range list.Manifests { | ||
| if m.Platform.OS == "linux" && m.Platform.Architecture == "amd64" { | ||
| manifest, fetchErr = manifests.Get(ctx, m.Digest) | ||
| goto interpret | ||
| } | ||
| } | ||
| return image.Info{}, errors.New("no suitable manifest (linux amd64) in manifestlist") | ||
| } | ||
|
|
||
| return img, nil | ||
| return info, nil | ||
| } |
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