add per domain semaphore to limit concurrent connections

This is a safer alternative until we figure out why
http.Transport based limiting fails.

Some connections like cache export/import do not have a
domain key atm and these connections use global pool.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

cache/opts.go

@@ -13,6 +13,7 @@ type DescHandler struct {
 	Provider       func(session.Group) content.Provider
 	Progress       progress.Controller
 	SnapshotLabels map[string]string
+	Ref            string // string representation of desc origin, can be used as a sync key
 }
 
 type DescHandlers map[digest.Digest]*DescHandler

cache/remote.go

@@ -208,7 +208,7 @@ func (p lazyRefProvider) Unlazy(ctx context.Context) error {
 		err := contentutil.Copy(ctx, p.ref.cm.ContentStore, &pullprogress.ProviderWithProgress{
 			Provider: p.dh.Provider(p.session),
 			Manager:  p.ref.cm.ContentStore,
-		}, p.desc, logs.LoggerFromContext(ctx))
+		}, p.desc, p.dh.Ref, logs.LoggerFromContext(ctx))
 		if err != nil {
 			return nil, err
 		}

cache/remotecache/export.go

@@ -58,11 +58,12 @@ type contentCacheExporter struct {
 	chains   *v1.CacheChains
 	ingester content.Ingester
 	oci      bool
+	ref      string
 }
 
-func NewExporter(ingester content.Ingester, oci bool) Exporter {
+func NewExporter(ingester content.Ingester, ref string, oci bool) Exporter {
 	cc := v1.NewCacheChains()
-	return &contentCacheExporter{CacheExporterTarget: cc, chains: cc, ingester: ingester, oci: oci}
+	return &contentCacheExporter{CacheExporterTarget: cc, chains: cc, ingester: ingester, oci: oci, ref: ref}
 }
 
 func (ce *contentCacheExporter) Finalize(ctx context.Context) (map[string]string, error) {
@@ -95,7 +96,7 @@ func (ce *contentCacheExporter) Finalize(ctx context.Context) (map[string]string
 			return nil, errors.Errorf("missing blob %s", l.Blob)
 		}
 		layerDone := oneOffProgress(ctx, fmt.Sprintf("writing layer %s", l.Blob))
-		if err := contentutil.Copy(ctx, ce.ingester, dgstPair.Provider, dgstPair.Descriptor, logs.LoggerFromContext(ctx)); err != nil {
+		if err := contentutil.Copy(ctx, ce.ingester, dgstPair.Provider, dgstPair.Descriptor, ce.ref, logs.LoggerFromContext(ctx)); err != nil {
 			return nil, layerDone(errors.Wrap(err, "error writing layer blob"))
 		}
 		layerDone(nil)

cache/remotecache/local/local.go

@@ -42,7 +42,7 @@ func ResolveCacheExporterFunc(sm *session.Manager) remotecache.ResolveCacheExpor
 		if err != nil {
 			return nil, err
 		}
-		return remotecache.NewExporter(cs, ociMediatypes), nil
+		return remotecache.NewExporter(cs, "", ociMediatypes), nil
 	}
 }
 

cache/remotecache/registry/registry.go

@@ -52,7 +52,7 @@ func ResolveCacheExporterFunc(sm *session.Manager, hosts docker.RegistryHosts) r
 		if err != nil {
 			return nil, err
 		}
-		return remotecache.NewExporter(contentutil.FromPusher(pusher), ociMediatypes), nil
+		return remotecache.NewExporter(contentutil.FromPusher(pusher), ref, ociMediatypes), nil
 	}
 }
 

source/containerimage/pull.go

@@ -237,6 +237,7 @@ func (p *puller) CacheKey(ctx context.Context, g session.Group, index int) (cach
 					Provider:       p.manifest.Provider,
 					Progress:       progressController,
 					SnapshotLabels: labels,
+					Ref:            p.manifest.Ref,
 				}
 			}
 		}

util/contentutil/copy.go

@@ -13,8 +13,8 @@ import (
 	"github.com/pkg/errors"
 )
 
-func Copy(ctx context.Context, ingester content.Ingester, provider content.Provider, desc ocispec.Descriptor, logger func([]byte)) error {
+func Copy(ctx context.Context, ingester content.Ingester, provider content.Provider, desc ocispec.Descriptor, ref string, logger func([]byte)) error {
-	if _, err := retryhandler.New(remotes.FetchHandler(ingester, &localFetcher{provider}), logger)(ctx, desc); err != nil {
+	if _, err := retryhandler.New(remotes.FetchHandler(ingester, &localFetcher{provider}), ref, logger)(ctx, desc); err != nil {
 		return err
 	}
 	return nil
@@ -65,7 +65,7 @@ func CopyChain(ctx context.Context, ingester content.Ingester, provider content.
 	handlers := []images.Handler{
 		images.ChildrenHandler(provider),
 		filterHandler,
-		retryhandler.New(remotes.FetchHandler(ingester, &localFetcher{provider}), func(_ []byte) {}),
+		retryhandler.New(remotes.FetchHandler(ingester, &localFetcher{provider}), "", func(_ []byte) {}),
 	}
 
 	if err := images.Dispatch(ctx, images.Handlers(handlers...), nil, desc); err != nil {
@@ -73,7 +73,7 @@ func CopyChain(ctx context.Context, ingester content.Ingester, provider content.
 	}
 
 	for i := len(manifestStack) - 1; i >= 0; i-- {
-		if err := Copy(ctx, ingester, provider, manifestStack[i], nil); err != nil {
+		if err := Copy(ctx, ingester, provider, manifestStack[i], "", nil); err != nil {
 			return errors.WithStack(err)
 		}
 	}

util/contentutil/copy_test.go

@@ -21,7 +21,7 @@ func TestCopy(t *testing.T) {
 	err := content.WriteBlob(ctx, b0, "foo", bytes.NewBuffer([]byte("foobar")), ocispec.Descriptor{Size: -1})
 	require.NoError(t, err)
 
-	err = Copy(ctx, b1, b0, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar")), Size: -1}, nil)
+	err = Copy(ctx, b1, b0, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar")), Size: -1}, "", nil)
 	require.NoError(t, err)
 
 	dt, err := content.ReadBlob(ctx, b1, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar"))})

util/contentutil/fetcher_test.go

@@ -26,7 +26,7 @@ func TestFetcher(t *testing.T) {
 	p := FromFetcher(f)
 
 	b1 := NewBuffer()
-	err = Copy(ctx, b1, p, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar")), Size: -1}, nil)
+	err = Copy(ctx, b1, p, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar")), Size: -1}, "", nil)
 	require.NoError(t, err)
 
 	dt, err := content.ReadBlob(ctx, b1, ocispec.Descriptor{Digest: digest.FromBytes([]byte("foobar"))})

util/imageutil/config.go

@@ -101,7 +101,7 @@ func Config(ctx context.Context, str string, resolver remotes.Resolver, cache Co
 	children := childrenConfigHandler(cache, platform)
 
 	handlers := []images.Handler{
-		retryhandler.New(remotes.FetchHandler(cache, fetcher), func(_ []byte) {}),
+		retryhandler.New(remotes.FetchHandler(cache, fetcher), str, func(_ []byte) {}),
 		children,
 	}
 	if err := images.Dispatch(ctx, images.Handlers(handlers...), nil, desc); err != nil {

util/pull/pull.go

@@ -148,7 +148,7 @@ func (p *Puller) PullManifests(ctx context.Context) (*PulledManifests, error) {
 		}
 		handlers = append(handlers,
 			filterLayerBlobs(metadata, &mu),
-			retryhandler.New(remotes.FetchHandler(p.ContentStore, fetcher), logs.LoggerFromContext(ctx)),
+			retryhandler.New(remotes.FetchHandler(p.ContentStore, fetcher), p.ref, logs.LoggerFromContext(ctx)),
 			childrenHandler,
 			dslHandler,
 		)

util/push/push.go

@@ -86,7 +86,7 @@ func Push(ctx context.Context, sm *session.Manager, sid string, provider content
 		}
 	})
 
-	pushHandler := retryhandler.New(remotes.PushHandler(pusher, provider), logs.LoggerFromContext(ctx))
+	pushHandler := retryhandler.New(remotes.PushHandler(pusher, provider), ref, logs.LoggerFromContext(ctx))
 	pushUpdateSourceHandler, err := updateDistributionSourceHandler(manager, pushHandler, ref)
 	if err != nil {
 		return err

util/resolver/retryhandler/retry.go

@@ -5,17 +5,43 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"sync"
 	"syscall"
 	"time"
 
 	"github.com/containerd/containerd/images"
 	remoteserrors "github.com/containerd/containerd/remotes/errors"
+	"github.com/docker/distribution/reference"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
+	"golang.org/x/sync/semaphore"
 )
 
-func New(f images.HandlerFunc, logger func([]byte)) images.HandlerFunc {
+var mu sync.Mutex
+var sem = map[string]*semaphore.Weighted{}
+
+const connsPerHost = 4
+
+func New(f images.HandlerFunc, ref string, logger func([]byte)) images.HandlerFunc {
+	if ref != "" {
+		if named, err := reference.ParseNormalizedNamed(ref); err == nil {
+			ref = reference.Domain(named)
+		}
+	}
+
 	return func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
+		mu.Lock()
+		s, ok := sem[ref]
+		if !ok {
+			s = semaphore.NewWeighted(connsPerHost)
+			sem[ref] = s
+		}
+		mu.Unlock()
+		if err := s.Acquire(ctx, 1); err != nil {
+			return nil, err
+		}
+		defer s.Release(1)
+
 		backoff := time.Second
 		for {
 			descs, err := f(ctx, desc)