dockerfile: deduplicate and cache config resolve requests

Signed-off-by: Tonis Tiigi <[email protected]>

Author: tonistiigi

frontend/dockerfile/builder/build.go

@@ -34,6 +34,7 @@ const (
 )
 
 func Build(ctx context.Context, c client.Client) (_ *client.Result, err error) {
+	c = &withResolveCache{Client: c}
 	bc, err := dockerui.NewClient(c)
 	if err != nil {
 		return nil, err

frontend/dockerfile/builder/resolvecache.go

@@ -0,0 +1,47 @@
+package builder
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/mitchellh/hashstructure/v2"
+	"github.com/moby/buildkit/client/llb/sourceresolver"
+	"github.com/moby/buildkit/frontend/gateway/client"
+	"github.com/moby/buildkit/util/flightcontrol"
+	digest "github.com/opencontainers/go-digest"
+)
+
+// withResolveCache wraps client.Client so that ResolveImageConfig
+// calls are cached and deduplicated via flightcontrol.CachedGroup
+type withResolveCache struct {
+	client.Client
+	g flightcontrol.CachedGroup[*resolveResult]
+}
+
+type resolveResult struct {
+	ref  string
+	dgst digest.Digest
+	cfg  []byte
+}
+
+var _ client.Client = &withResolveCache{}
+
+func (c *withResolveCache) ResolveImageConfig(ctx context.Context, ref string, opt sourceresolver.Opt) (string, digest.Digest, []byte, error) {
+	c.g.CacheError = true
+	optHash, err := hashstructure.Hash(opt, hashstructure.FormatV2, nil)
+	if err != nil {
+		return "", "", nil, err
+	}
+	key := fmt.Sprintf("%s,%d", ref, optHash)
+	res, err := c.g.Do(ctx, key, func(ctx context.Context) (*resolveResult, error) {
+		ref, dgst, cfg, err := c.Client.ResolveImageConfig(ctx, ref, opt)
+		if err != nil {
+			return nil, err
+		}
+		return &resolveResult{ref, dgst, cfg}, nil
+	})
+	if err != nil {
+		return "", "", nil, err
+	}
+	return res.ref, res.dgst, res.cfg, nil
+}