To avoid any network use unless necessary, delay establishing authorization

challenges with the upstream until any proxied data is found not to be local.

Implement auth challenges behind an interface and add to unit tests.  Also,
remove a non-sensical unit test.

Signed-off-by: Richard Scothern <richard.scothern@docker.com>

docs/proxy/proxyauth.go

@@ -8,6 +8,7 @@ import (
 )
 
 const tokenURL = "https://auth.docker.io/token"
+const challengeHeader = "Docker-Distribution-Api-Version"
 
 type userpass struct {
 	username string
@@ -24,12 +25,8 @@ func (c credentials) Basic(u *url.URL) (string, string) {
 	return up.username, up.password
 }
 
-// ConfigureAuth authorizes with the upstream registry
+// ConfigureAuth stores credentials for challenge responses
-func ConfigureAuth(remoteURL, username, password string, cm auth.ChallengeManager) (auth.CredentialStore, error) {
+func configureAuth(username, password string) (auth.CredentialStore, error) {
-	if err := ping(cm, remoteURL+"/v2/", "Docker-Distribution-Api-Version"); err != nil {
-		return nil, err
-	}
-
 	creds := map[string]userpass{
 		tokenURL: {
 			username: username,

docs/proxy/proxyblobstore.go

@@ -22,6 +22,7 @@ type proxyBlobStore struct {
 	remoteStore    distribution.BlobService
 	scheduler      *scheduler.TTLExpirationScheduler
 	repositoryName reference.Named
+	authChallenger authChallenger
 }
 
 var _ distribution.BlobStore = &proxyBlobStore{}
@@ -121,6 +122,10 @@ func (pbs *proxyBlobStore) ServeBlob(ctx context.Context, w http.ResponseWriter,
 		return nil
 	}
 
+	if err := pbs.authChallenger.tryEstablishChallenges(ctx); err != nil {
+		return err
+	}
+
 	mu.Lock()
 	_, ok := inflight[dgst]
 	if ok {
@@ -162,6 +167,10 @@ func (pbs *proxyBlobStore) Stat(ctx context.Context, dgst digest.Digest) (distri
 		return distribution.Descriptor{}, err
 	}
 
+	if err := pbs.authChallenger.tryEstablishChallenges(ctx); err != nil {
+		return distribution.Descriptor{}, err
+	}
+
 	return pbs.remoteStore.Stat(ctx, dgst)
 }
 

docs/proxy/proxyblobstore_test.go

@@ -168,6 +168,7 @@ func makeTestEnv(t *testing.T, name string) *testEnv {
 		remoteStore:    truthBlobs,
 		localStore:     localBlobs,
 		scheduler:      s,
+		authChallenger: &mockChallenger{},
 	}
 
 	te := &testEnv{
@@ -242,6 +243,11 @@ func TestProxyStoreStat(t *testing.T) {
 	if (*remoteStats)["stat"] != remoteBlobCount {
 		t.Errorf("Unexpected remote stat count")
 	}
+
+	if te.store.authChallenger.(*mockChallenger).count != len(te.inRemote) {
+		t.Fatalf("Unexpected auth challenge count, got %#v", te.store.authChallenger)
+	}
+
 }
 
 func TestProxyStoreServeHighConcurrency(t *testing.T) {

docs/proxy/proxymanifeststore.go

@@ -19,6 +19,7 @@ type proxyManifestStore struct {
 	remoteManifests distribution.ManifestService
 	repositoryName  reference.Named
 	scheduler       *scheduler.TTLExpirationScheduler
+	authChallenger  authChallenger
 }
 
 var _ distribution.ManifestService = &proxyManifestStore{}
@@ -31,7 +32,9 @@ func (pms proxyManifestStore) Exists(ctx context.Context, dgst digest.Digest) (b
 	if exists {
 		return true, nil
 	}
-
+	if err := pms.authChallenger.tryEstablishChallenges(ctx); err != nil {
+		return false, err
+	}
 	return pms.remoteManifests.Exists(ctx, dgst)
 }
 
@@ -41,6 +44,10 @@ func (pms proxyManifestStore) Get(ctx context.Context, dgst digest.Digest, optio
 	var fromRemote bool
 	manifest, err := pms.localManifests.Get(ctx, dgst, options...)
 	if err != nil {
+		if err := pms.authChallenger.tryEstablishChallenges(ctx); err != nil {
+			return nil, err
+		}
+
 		manifest, err = pms.remoteManifests.Get(ctx, dgst, options...)
 		if err != nil {
 			return nil, err

docs/proxy/proxymanifeststore_test.go

@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"io"
+	"sync"
 	"testing"
 
 	"github.com/docker/distribution"
@@ -64,6 +65,20 @@ func (sm statsManifest) Put(ctx context.Context, manifest distribution.Manifest,
 }
 */
 
+type mockChallenger struct {
+	sync.Mutex
+	count int
+}
+
+// Called for remote operations only
+func (mc *mockChallenger) tryEstablishChallenges(context.Context) error {
+	mc.Lock()
+	defer mc.Unlock()
+
+	mc.count++
+	return nil
+}
+
 func newManifestStoreTestEnv(t *testing.T, name, tag string) *manifestStoreTestEnv {
 	nameRef, err := reference.ParseNamed(name)
 	if err != nil {
@@ -120,6 +135,7 @@ func newManifestStoreTestEnv(t *testing.T, name, tag string) *manifestStoreTestE
 			remoteManifests: truthManifests,
 			scheduler:       s,
 			repositoryName:  nameRef,
+			authChallenger:  &mockChallenger{},
 		},
 	}
 }
@@ -198,6 +214,10 @@ func TestProxyManifests(t *testing.T) {
 		t.Errorf("Unexpected exists count : \n%v \n%v", localStats, remoteStats)
 	}
 
+	if env.manifests.authChallenger.(*mockChallenger).count != 1 {
+		t.Fatalf("Expected 1 auth challenge, got %#v", env.manifests.authChallenger)
+	}
+
 	// Get - should succeed and pull manifest into local
 	_, err = env.manifests.Get(ctx, env.manifestDigest)
 	if err != nil {
@@ -212,6 +232,10 @@ func TestProxyManifests(t *testing.T) {
 		t.Errorf("Expected local put")
 	}
 
+	if env.manifests.authChallenger.(*mockChallenger).count != 2 {
+		t.Fatalf("Expected 2 auth challenges, got %#v", env.manifests.authChallenger)
+	}
+
 	// Stat - should only go to local
 	exists, err = env.manifests.Exists(ctx, env.manifestDigest)
 	if err != nil {
@@ -225,17 +249,18 @@ func TestProxyManifests(t *testing.T) {
 		t.Errorf("Unexpected exists count")
 	}
 
-	// Get - should get from remote, to test freshness
+	if env.manifests.authChallenger.(*mockChallenger).count != 2 {
+		t.Fatalf("Expected 2 auth challenges, got %#v", env.manifests.authChallenger)
+	}
+
+	// Get proxied - won't require another authchallenge
 	_, err = env.manifests.Get(ctx, env.manifestDigest)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if (*remoteStats)["get"] != 2 && (*remoteStats)["exists"] != 1 && (*localStats)["put"] != 1 {
+	if env.manifests.authChallenger.(*mockChallenger).count != 2 {
-		t.Errorf("Unexpected get count")
+		t.Fatalf("Expected 2 auth challenges, got %#v", env.manifests.authChallenger)
-	}
 	}
 
-func TestProxyTagService(t *testing.T) {
-
 }

docs/proxy/proxyregistry.go

@@ -1,10 +1,11 @@
 package proxy
 
 import (
+	"fmt"
 	"net/http"
 	"net/url"
+	"sync"
 
-	"fmt"
 	"github.com/docker/distribution"
 	"github.com/docker/distribution/configuration"
 	"github.com/docker/distribution/context"
@@ -20,12 +21,9 @@ import (
 // proxyingRegistry fetches content from a remote registry and caches it locally
 type proxyingRegistry struct {
 	embedded       distribution.Namespace // provides local registry functionality
-
 	scheduler      *scheduler.TTLExpirationScheduler
-
 	remoteURL      string
-	credentialStore  auth.CredentialStore
+	authChallenger authChallenger
-	challengeManager auth.ChallengeManager
 }
 
 // NewRegistryPullThroughCache creates a registry acting as a pull through cache
@@ -93,8 +91,7 @@ func NewRegistryPullThroughCache(ctx context.Context, registry distribution.Name
 		return nil, err
 	}
 
-	challengeManager := auth.NewSimpleChallengeManager()
+	cs, err := configureAuth(config.Username, config.Password)
-	cs, err := ConfigureAuth(config.RemoteURL, config.Username, config.Password, challengeManager)
 	if err != nil {
 		return nil, err
 	}
@@ -102,9 +99,12 @@ func NewRegistryPullThroughCache(ctx context.Context, registry distribution.Name
 	return &proxyingRegistry{
 		embedded:  registry,
 		scheduler: s,
-		challengeManager: challengeManager,
-		credentialStore:  cs,
 		remoteURL: config.RemoteURL,
+		authChallenger: &remoteAuthChallenger{
+			remoteURL:        config.RemoteURL,
+			challengeManager: auth.NewSimpleChallengeManager(),
+			credentialStore:  cs,
+		},
 	}, nil
 }
 
@@ -117,8 +117,13 @@ func (pr *proxyingRegistry) Repositories(ctx context.Context, repos []string, la
 }
 
 func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named) (distribution.Repository, error) {
+	hcm, ok := pr.authChallenger.(*remoteAuthChallenger)
+	if !ok {
+		return nil, fmt.Errorf("unexpected challenge manager type %T", pr.authChallenger)
+	}
+
 	tr := transport.NewTransport(http.DefaultTransport,
-		auth.NewAuthorizer(pr.challengeManager, auth.NewTokenHandler(http.DefaultTransport, pr.credentialStore, name.Name(), "pull")))
+		auth.NewAuthorizer(hcm.challengeManager, auth.NewTokenHandler(http.DefaultTransport, hcm.credentialStore, name.Name(), "pull")))
 
 	localRepo, err := pr.embedded.Repository(ctx, name)
 	if err != nil {
@@ -145,6 +150,7 @@ func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named
 			remoteStore:    remoteRepo.Blobs(ctx),
 			scheduler:      pr.scheduler,
 			repositoryName: name,
+			authChallenger: pr.authChallenger,
 		},
 		manifests: &proxyManifestStore{
 			repositoryName:  name,
@@ -152,15 +158,53 @@ func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named
 			remoteManifests: remoteManifests,
 			ctx:             ctx,
 			scheduler:       pr.scheduler,
+			authChallenger:  pr.authChallenger,
 		},
 		name: name,
 		tags: &proxyTagService{
 			localTags:      localRepo.Tags(ctx),
 			remoteTags:     remoteRepo.Tags(ctx),
+			authChallenger: pr.authChallenger,
 		},
 	}, nil
 }
 
+// authChallenger encapsulates a request to the upstream to establish credential challenges
+type authChallenger interface {
+	tryEstablishChallenges(context.Context) error
+}
+
+type remoteAuthChallenger struct {
+	remoteURL string
+	sync.Mutex
+	challengeManager auth.ChallengeManager
+	credentialStore  auth.CredentialStore
+}
+
+// tryEstablishChallenges will attempt to get a challenge types for the upstream if none currently exist
+func (hcm *remoteAuthChallenger) tryEstablishChallenges(ctx context.Context) error {
+	hcm.Lock()
+	defer hcm.Unlock()
+
+	remoteURL := hcm.remoteURL + "/v2/"
+	challenges, err := hcm.challengeManager.GetChallenges(remoteURL)
+	if err != nil {
+		return err
+	}
+
+	if len(challenges) > 0 {
+		return nil
+	}
+
+	// establish challenge type with upstream
+	if err := ping(hcm.challengeManager, remoteURL, challengeHeader); err != nil {
+		return err
+	}
+
+	context.GetLogger(ctx).Infof("Challenge established with upstream : %s %s", remoteURL, hcm.challengeManager)
+	return nil
+}
+
 // proxiedRepository uses proxying blob and manifest services to serve content
 // locally, or pulling it through from a remote and caching it locally if it doesn't
 // already exist

docs/proxy/proxytagservice.go

@@ -9,6 +9,7 @@ import (
 type proxyTagService struct {
 	localTags      distribution.TagService
 	remoteTags     distribution.TagService
+	authChallenger authChallenger
 }
 
 var _ distribution.TagService = proxyTagService{}
@@ -17,6 +18,8 @@ var _ distribution.TagService = proxyTagService{}
 // tag service first and then caching it locally.  If the remote is unavailable
 // the local association is returned
 func (pt proxyTagService) Get(ctx context.Context, tag string) (distribution.Descriptor, error) {
+	err := pt.authChallenger.tryEstablishChallenges(ctx)
+	if err == nil {
 		desc, err := pt.remoteTags.Get(ctx, tag)
 		if err == nil {
 			err := pt.localTags.Tag(ctx, tag, desc)
@@ -25,8 +28,9 @@ func (pt proxyTagService) Get(ctx context.Context, tag string) (distribution.Des
 			}
 			return desc, nil
 		}
+	}
 
-	desc, err = pt.localTags.Get(ctx, tag)
+	desc, err := pt.localTags.Get(ctx, tag)
 	if err != nil {
 		return distribution.Descriptor{}, err
 	}
@@ -46,10 +50,13 @@ func (pt proxyTagService) Untag(ctx context.Context, tag string) error {
 }
 
 func (pt proxyTagService) All(ctx context.Context) ([]string, error) {
+	err := pt.authChallenger.tryEstablishChallenges(ctx)
+	if err == nil {
 		tags, err := pt.remoteTags.All(ctx)
 		if err == nil {
 			return tags, err
 		}
+	}
 	return pt.localTags.All(ctx)
 }
 

docs/proxy/proxytagservice_test.go

@@ -71,6 +71,7 @@ func testProxyTagService(local, remote map[string]distribution.Descriptor) *prox
 	return &proxyTagService{
 		localTags:      &mockTagStore{mapping: local},
 		remoteTags:     &mockTagStore{mapping: remote},
+		authChallenger: &mockChallenger{},
 	}
 }
 
@@ -87,6 +88,10 @@ func TestGet(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	if proxyTags.authChallenger.(*mockChallenger).count != 1 {
+		t.Fatalf("Expected 1 auth challenge call, got %#v", proxyTags.authChallenger)
+	}
+
 	if d != remoteDesc {
 		t.Fatal("unable to get put tag")
 	}
@@ -112,6 +117,10 @@ func TestGet(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	if proxyTags.authChallenger.(*mockChallenger).count != 2 {
+		t.Fatalf("Expected 2 auth challenge calls, got %#v", proxyTags.authChallenger)
+	}
+
 	if d != newRemoteDesc {
 		t.Fatal("unable to get put tag")
 	}
@@ -142,7 +151,11 @@ func TestGet(t *testing.T) {
 		t.Fatal("untagged tag should be pulled through")
 	}
 
-	// Add another tag.  Ensure both tags appear in enumerate
+	if proxyTags.authChallenger.(*mockChallenger).count != 3 {
+		t.Fatalf("Expected 3 auth challenge calls, got %#v", proxyTags.authChallenger)
+	}
+
+	// Add another tag.  Ensure both tags appear in 'All'
 	err = proxyTags.remoteTags.Tag(ctx, "funtag", distribution.Descriptor{Size: 42})
 	if err != nil {
 		t.Fatal(err)
@@ -161,4 +174,8 @@ func TestGet(t *testing.T) {
 	if all[0] != "funtag" && all[1] != "remote" {
 		t.Fatalf("Unexpected tags returned from All() : %v ", all)
 	}
+
+	if proxyTags.authChallenger.(*mockChallenger).count != 4 {
+		t.Fatalf("Expected 4 auth challenge calls, got %#v", proxyTags.authChallenger)
+	}
 }