Merge pull request #1471 from RichardScothern/tag-headers

Enable proxying registries to downgrade fetched manifests to Schema 1.

docs/client/repository.go

@@ -292,9 +292,18 @@ func (t *tags) Get(ctx context.Context, tag string) (distribution.Descriptor, er
 	if err != nil {
 		return distribution.Descriptor{}, err
 	}
-	var attempts int
-	resp, err := t.client.Head(u)
 
+	req, err := http.NewRequest("HEAD", u, nil)
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	for _, t := range distribution.ManifestMediaTypes() {
+		req.Header.Add("Accept", t)
+	}
+
+	var attempts int
+	resp, err := t.client.Do(req)
 check:
 	if err != nil {
 		return distribution.Descriptor{}, err
@@ -304,7 +313,16 @@ check:
 	case resp.StatusCode >= 200 && resp.StatusCode < 400:
 		return descriptorFromResponse(resp)
 	case resp.StatusCode == http.StatusMethodNotAllowed:
-		resp, err = t.client.Get(u)
+		req, err = http.NewRequest("GET", u, nil)
+		if err != nil {
+			return distribution.Descriptor{}, err
+		}
+
+		for _, t := range distribution.ManifestMediaTypes() {
+			req.Header.Add("Accept", t)
+		}
+
+		resp, err = t.client.Do(req)
 		attempts++
 		if attempts > 1 {
 			return distribution.Descriptor{}, err

docs/proxy/proxyblobstore.go

@@ -174,6 +174,28 @@ func (pbs *proxyBlobStore) Stat(ctx context.Context, dgst digest.Digest) (distri
 	return pbs.remoteStore.Stat(ctx, dgst)
 }
 
+func (pbs *proxyBlobStore) Get(ctx context.Context, dgst digest.Digest) ([]byte, error) {
+	blob, err := pbs.localStore.Get(ctx, dgst)
+	if err == nil {
+		return blob, nil
+	}
+
+	if err := pbs.authChallenger.tryEstablishChallenges(ctx); err != nil {
+		return []byte{}, err
+	}
+
+	blob, err = pbs.remoteStore.Get(ctx, dgst)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	_, err = pbs.localStore.Put(ctx, "", blob)
+	if err != nil {
+		return []byte{}, err
+	}
+	return blob, nil
+}
+
 // Unsupported functions
 func (pbs *proxyBlobStore) Put(ctx context.Context, mediaType string, p []byte) (distribution.Descriptor, error) {
 	return distribution.Descriptor{}, distribution.ErrUnsupported
@@ -195,10 +217,6 @@ func (pbs *proxyBlobStore) Open(ctx context.Context, dgst digest.Digest) (distri
 	return nil, distribution.ErrUnsupported
 }
 
-func (pbs *proxyBlobStore) Get(ctx context.Context, dgst digest.Digest) ([]byte, error) {
-	return nil, distribution.ErrUnsupported
-}
-
 func (pbs *proxyBlobStore) Delete(ctx context.Context, dgst digest.Digest) error {
 	return distribution.ErrUnsupported
 }

docs/proxy/proxyblobstore_test.go

@@ -218,6 +218,40 @@ func populate(t *testing.T, te *testEnv, blobCount, size, numUnique int) {
 	te.inRemote = inRemote
 	te.numUnique = numUnique
 }
+func TestProxyStoreGet(t *testing.T) {
+	te := makeTestEnv(t, "foo/bar")
+
+	localStats := te.LocalStats()
+	remoteStats := te.RemoteStats()
+
+	populate(t, te, 1, 10, 1)
+	_, err := te.store.Get(te.ctx, te.inRemote[0].Digest)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if (*localStats)["get"] != 1 && (*localStats)["put"] != 1 {
+		t.Errorf("Unexpected local counts")
+	}
+
+	if (*remoteStats)["get"] != 1 {
+		t.Errorf("Unexpected remote get count")
+	}
+
+	_, err = te.store.Get(te.ctx, te.inRemote[0].Digest)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if (*localStats)["get"] != 2 && (*localStats)["put"] != 1 {
+		t.Errorf("Unexpected local counts")
+	}
+
+	if (*remoteStats)["get"] != 1 {
+		t.Errorf("Unexpected remote get count")
+	}
+
+}
 
 func TestProxyStoreStat(t *testing.T) {
 	te := makeTestEnv(t, "foo/bar")