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Allow conditional fetching of manifests with the registry client.

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Add a functional argument to pass a digest to (ManifestService).GetByTag().
If the digest matches an empty manifest and nil error are returned.

See 6bedf7d1cd for server implementation.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
This commit is contained in:
Richard Scothern 2015-07-14 16:25:37 -07:00
parent af3f674323
commit caf989a572
3 changed files with 83 additions and 18 deletions
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36
docs/client/repository.go
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@ -75,6 +75,7 @@ func (r *repository) Manifests() distribution.ManifestService {
name: r.Name(),
ub: r.ub,
client: r.client,
etags: make(map[string]string),
}
}
@ -104,6 +105,7 @@ type manifests struct {
name string
ub *v2.URLBuilder
client *http.Client
etags map[string]string
}
func (ms *manifests) Tags() ([]string, error) {
@ -173,13 +175,40 @@ func (ms *manifests) Get(dgst digest.Digest) (*manifest.SignedManifest, error) {
return ms.GetByTag(dgst.String())
}
func (ms *manifests) GetByTag(tag string) (*manifest.SignedManifest, error) {
// AddEtagToTag allows a client to supply an eTag to GetByTag which will
// be used for a conditional HTTP request. If the eTag matches, a nil
// manifest and nil error will be returned.
func AddEtagToTag(tagName, dgst string) distribution.ManifestServiceOption {
return func(ms distribution.ManifestService) error {
if ms, ok := ms.(*manifests); ok {
ms.etags[tagName] = dgst
return nil
}
return fmt.Errorf("etag options is a client-only option")
}
}
func (ms *manifests) GetByTag(tag string, options ...distribution.ManifestServiceOption) (*manifest.SignedManifest, error) {
for _, option := range options {
err := option(ms)
if err != nil {
return nil, err
}
}
u, err := ms.ub.BuildManifestURL(ms.name, tag)
if err != nil {
return nil, err
}
req, err := http.NewRequest("GET", u, nil)
if err != nil {
return nil, err
}
resp, err := ms.client.Get(u)
if _, ok := ms.etags[tag]; ok {
req.Header.Set("eTag", ms.etags[tag])
}
resp, err := ms.client.Do(req)
if err != nil {
return nil, err
}
@ -193,8 +222,9 @@ func (ms *manifests) GetByTag(tag string) (*manifest.SignedManifest, error) {
if err := decoder.Decode(&sm); err != nil {
return nil, err
}
return &sm, nil
case http.StatusNotModified:
return nil, nil
default:
return nil, handleErrorResponse(resp)
}