Merge pull request #203 from thaJeztah/18.09_backport_gcr_workaround

[18.09 backport] builder: add workaround for gcr auth issue

builder/builder-next/adapters/containerimage/pull.go

@@ -8,6 +8,7 @@ import (
 	"io/ioutil"
 	"runtime"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/containerd/containerd/content"
@@ -57,13 +58,15 @@ type SourceOpt struct {
 
 type imageSource struct {
 	SourceOpt
-	g flightcontrol.Group
+	g             flightcontrol.Group
+	resolverCache *resolverCache
 }
 
 // NewSource creates a new image source
 func NewSource(opt SourceOpt) (source.Source, error) {
 	is := &imageSource{
-		SourceOpt: opt,
+		SourceOpt:     opt,
+		resolverCache: newResolverCache(),
 	}
 
 	return is, nil
@@ -74,6 +77,9 @@ func (is *imageSource) ID() string {
 }
 
 func (is *imageSource) getResolver(ctx context.Context, rfn resolver.ResolveOptionsFunc, ref string) remotes.Resolver {
+	if res := is.resolverCache.Get(ctx, ref); res != nil {
+		return res
+	}
 	opt := docker.ResolverOptions{
 		Client: tracing.DefaultClient,
 	}
@@ -82,6 +88,7 @@ func (is *imageSource) getResolver(ctx context.Context, rfn resolver.ResolveOpti
 	}
 	opt.Credentials = is.getCredentialsFromSession(ctx)
 	r := docker.NewResolver(opt)
+	r = is.resolverCache.Add(ctx, ref, r)
 	return r
 }
 
@@ -380,6 +387,11 @@ func (p *puller) Snapshot(ctx context.Context) (cache.ImmutableRef, error) {
 		return nil, err
 	}
 
+	// workaround for GCR bug that requires a request to manifest endpoint for authentication to work.
+	// if current resolver has not used manifests do a dummy request.
+	// in most cases resolver should be cached and extra request is not needed.
+	ensureManifestRequested(ctx, p.resolver, p.ref)
+
 	var (
 		schema1Converter *schema1.Converter
 		handlers         []images.Handler
@@ -791,3 +803,90 @@ func resolveModeToString(rm source.ResolveMode) string {
 	}
 	return ""
 }
+
+type resolverCache struct {
+	mu sync.Mutex
+	m  map[string]cachedResolver
+}
+
+type cachedResolver struct {
+	timeout time.Time
+	remotes.Resolver
+	counter int64
+}
+
+func (cr *cachedResolver) Resolve(ctx context.Context, ref string) (name string, desc ocispec.Descriptor, err error) {
+	atomic.AddInt64(&cr.counter, 1)
+	return cr.Resolver.Resolve(ctx, ref)
+}
+
+func (r *resolverCache) Add(ctx context.Context, ref string, resolver remotes.Resolver) remotes.Resolver {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	ref = r.repo(ref) + "-" + session.FromContext(ctx)
+
+	cr, ok := r.m[ref]
+	cr.timeout = time.Now().Add(time.Minute)
+	if ok {
+		return &cr
+	}
+
+	cr.Resolver = resolver
+	r.m[ref] = cr
+	return &cr
+}
+
+func (r *resolverCache) repo(refStr string) string {
+	ref, err := distreference.ParseNormalizedNamed(refStr)
+	if err != nil {
+		return refStr
+	}
+	return ref.Name()
+}
+
+func (r *resolverCache) Get(ctx context.Context, ref string) remotes.Resolver {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	ref = r.repo(ref) + "-" + session.FromContext(ctx)
+
+	cr, ok := r.m[ref]
+	if !ok {
+		return nil
+	}
+	return &cr
+}
+
+func (r *resolverCache) clean(now time.Time) {
+	r.mu.Lock()
+	for k, cr := range r.m {
+		if now.After(cr.timeout) {
+			delete(r.m, k)
+		}
+	}
+	r.mu.Unlock()
+}
+
+func newResolverCache() *resolverCache {
+	rc := &resolverCache{
+		m: map[string]cachedResolver{},
+	}
+	t := time.NewTicker(time.Minute)
+	go func() {
+		for {
+			rc.clean(<-t.C)
+		}
+	}()
+	return rc
+}
+
+func ensureManifestRequested(ctx context.Context, res remotes.Resolver, ref string) {
+	cr, ok := res.(*cachedResolver)
+	if !ok {
+		return
+	}
+	if atomic.LoadInt64(&cr.counter) == 0 {
+		res.Resolve(ctx, ref)
+	}
+}