From 7144936612ad3e5064920fc817469fe3b1c4f4a1 Mon Sep 17 00:00:00 2001
From: Richard Scothern <richard.scothern@gmail.com>
Date: Wed, 17 Feb 2016 16:32:23 -0800
Subject: [PATCH] Enable proxying registries to downgrade fetched manifests to
 Schema 1.

Ensure Accept headers are sent with TagService.Get (which hits manifest
endpoints).  Add support for remote Get and Put for the proxied blobstore.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
---
 registry/client/repository.go         | 24 ++++++++++++++++---
 registry/proxy/proxyblobstore.go      | 26 ++++++++++++++++----
 registry/proxy/proxyblobstore_test.go | 34 +++++++++++++++++++++++++++
 3 files changed, 77 insertions(+), 7 deletions(-)

diff --git a/registry/client/repository.go b/registry/client/repository.go
index ebf44d473..830749f1b 100644
--- a/registry/client/repository.go
+++ b/registry/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
diff --git a/registry/proxy/proxyblobstore.go b/registry/proxy/proxyblobstore.go
index 5f1a9c504..7a6d7ea27 100644
--- a/registry/proxy/proxyblobstore.go
+++ b/registry/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
 }
diff --git a/registry/proxy/proxyblobstore_test.go b/registry/proxy/proxyblobstore_test.go
index 4d63aa423..b93b53433 100644
--- a/registry/proxy/proxyblobstore_test.go
+++ b/registry/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")