registry: remove dependency on logrus for client

To simplify the vendoring story for the client, we have now removed the
requirement for `logrus` and the forked `context` package (usually
imported as `dcontext`). We inject the logger via the metrics tracker
for the blob cache and via options on the token handler. We preserve
logs on the proxy cache for that case. Clients expecting these log
messages may need to be updated accordingly.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

registry/client/auth/session.go

@@ -13,7 +13,6 @@ import (
 	"github.com/docker/distribution/registry/client"
 	"github.com/docker/distribution/registry/client/auth/challenge"
 	"github.com/docker/distribution/registry/client/transport"
-	"github.com/sirupsen/logrus"
 )
 
 var (
@@ -135,6 +134,8 @@ type tokenHandler struct {
 	tokenLock       sync.Mutex
 	tokenCache      string
 	tokenExpiration time.Time
+
+	logger Logger
 }
 
 // Scope is a type which is serializable to a string
@@ -176,6 +177,18 @@ func (rs RegistryScope) String() string {
 	return fmt.Sprintf("registry:%s:%s", rs.Name, strings.Join(rs.Actions, ","))
 }
 
+// Logger defines the injectable logging interface, used on TokenHandlers.
+type Logger interface {
+	Debugf(format string, args ...interface{})
+}
+
+func logDebugf(logger Logger, format string, args ...interface{}) {
+	if logger == nil {
+		return
+	}
+	logger.Debugf(format, args...)
+}
+
 // TokenHandlerOptions is used to configure a new token handler
 type TokenHandlerOptions struct {
 	Transport   http.RoundTripper
@@ -185,6 +198,7 @@ type TokenHandlerOptions struct {
 	ForceOAuth    bool
 	ClientID      string
 	Scopes        []Scope
+	Logger        Logger
 }
 
 // An implementation of clock for providing real time data.
@@ -220,6 +234,7 @@ func NewTokenHandlerWithOptions(options TokenHandlerOptions) AuthenticationHandl
 		clientID:      options.ClientID,
 		scopes:        options.Scopes,
 		clock:         realClock{},
+		logger:        options.Logger,
 	}
 
 	return handler
@@ -348,7 +363,7 @@ func (th *tokenHandler) fetchTokenWithOAuth(realm *url.URL, refreshToken, servic
 	if tr.ExpiresIn < minimumTokenLifetimeSeconds {
 		// The default/minimum lifetime.
 		tr.ExpiresIn = minimumTokenLifetimeSeconds
-		logrus.Debugf("Increasing token expiration to: %d seconds", tr.ExpiresIn)
+		logDebugf(th.logger, "Increasing token expiration to: %d seconds", tr.ExpiresIn)
 	}
 
 	if tr.IssuedAt.IsZero() {
@@ -439,7 +454,7 @@ func (th *tokenHandler) fetchTokenWithBasicAuth(realm *url.URL, service string,
 	if tr.ExpiresIn < minimumTokenLifetimeSeconds {
 		// The default/minimum lifetime.
 		tr.ExpiresIn = minimumTokenLifetimeSeconds
-		logrus.Debugf("Increasing token expiration to: %d seconds", tr.ExpiresIn)
+		logDebugf(th.logger, "Increasing token expiration to: %d seconds", tr.ExpiresIn)
 	}
 
 	if tr.IssuedAt.IsZero() {

registry/proxy/proxyregistry.go

@@ -121,8 +121,21 @@ func (pr *proxyingRegistry) Repositories(ctx context.Context, repos []string, la
 func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named) (distribution.Repository, error) {
 	c := pr.authChallenger
 
+	tkopts := auth.TokenHandlerOptions{
+		Transport:   http.DefaultTransport,
+		Credentials: c.credentialStore(),
+		Scopes: []auth.Scope{
+			auth.RepositoryScope{
+				Repository: name.Name(),
+				Actions:    []string{"pull"},
+			},
+		},
+		Logger: dcontext.GetLogger(ctx),
+	}
+
 	tr := transport.NewTransport(http.DefaultTransport,
-		auth.NewAuthorizer(c.challengeManager(), auth.NewTokenHandler(http.DefaultTransport, c.credentialStore(), name.Name(), "pull")))
+		auth.NewAuthorizer(c.challengeManager(),
+			auth.NewTokenHandlerWithOptions(tkopts)))
 
 	localRepo, err := pr.embedded.Repository(ctx, name)
 	if err != nil {

registry/storage/blobcachemetrics.go

@@ -1,9 +1,11 @@
 package storage
 
 import (
+	"context"
 	"expvar"
 	"sync/atomic"
 
+	dcontext "github.com/docker/distribution/context"
 	"github.com/docker/distribution/registry/storage/cache"
 )
 
@@ -25,6 +27,10 @@ func (bsc *blobStatCollector) Metrics() cache.Metrics {
 	return bsc.metrics
 }
 
+func (bsc *blobStatCollector) Logger(ctx context.Context) cache.Logger {
+	return dcontext.GetLogger(ctx)
+}
+
 // blobStatterCacheMetrics keeps track of cache metrics for blob descriptor
 // cache requests. Note this is kept globally and made available via expvar.
 // For more detailed metrics, its recommend to instrument a particular cache

registry/storage/cache/cachedblobdescriptorstore.go

@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/docker/distribution"
-	dcontext "github.com/docker/distribution/context"
 	"github.com/opencontainers/go-digest"
 )
 
@@ -17,12 +16,20 @@ type Metrics struct {
 	Misses   uint64
 }
 
+// Logger can be provided on the MetricsTracker to log errors.
+//
+// Usually, this is just a proxy to dcontext.GetLogger.
+type Logger interface {
+	Errorf(format string, args ...interface{})
+}
+
 // MetricsTracker represents a metric tracker
 // which simply counts the number of hits and misses.
 type MetricsTracker interface {
 	Hit()
 	Miss()
 	Metrics() Metrics
+	Logger(context.Context) Logger
 }
 
 type cachedBlobStatter struct {
@@ -54,7 +61,7 @@ func (cbds *cachedBlobStatter) Stat(ctx context.Context, dgst digest.Digest) (di
 	desc, err := cbds.cache.Stat(ctx, dgst)
 	if err != nil {
 		if err != distribution.ErrBlobUnknown {
-			dcontext.GetLogger(ctx).Errorf("error retrieving descriptor from cache: %v", err)
+			logErrorf(ctx, cbds.tracker, "error retrieving descriptor from cache: %v", err)
 		}
 
 		goto fallback
@@ -74,7 +81,7 @@ fallback:
 	}
 
 	if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
-		dcontext.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
+		logErrorf(ctx, cbds.tracker, "error adding descriptor %v to cache: %v", desc.Digest, err)
 	}
 
 	return desc, err
@@ -96,7 +103,19 @@ func (cbds *cachedBlobStatter) Clear(ctx context.Context, dgst digest.Digest) er
 
 func (cbds *cachedBlobStatter) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
 	if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
-		dcontext.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
+		logErrorf(ctx, cbds.tracker, "error adding descriptor %v to cache: %v", desc.Digest, err)
 	}
 	return nil
 }
+
+func logErrorf(ctx context.Context, tracker MetricsTracker, format string, args ...interface{}) {
+	if tracker == nil {
+		return
+	}
+
+	logger := tracker.Logger(ctx)
+	if logger == nil {
+		return
+	}
+	logger.Errorf(format, args...)
+}