Don't run cache exporter for all

cache/refs.go

@@ -746,6 +746,8 @@ func (sr *immutableRef) ociDesc(ctx context.Context, dhs DescHandlers, preferNon
 		desc.Annotations["buildkit/createdat"] = string(createdAt)
 	}
 
+	desc.Annotations["earthly/ref"] = sr.ID()
+
 	return desc, nil
 }
 

solver/llbsolver/inline.go

@@ -71,6 +71,17 @@ func earthlyInlineCacheDigests(ctx context.Context, job *solver.Job, exp exporte
 
 	cacheItems := []earthlyInlineCacheItem{}
 
+	// fmt.Println("inline cache pairs")
+	// spew.Dump(res.CacheKeys())
+	// for _, desc := range remote.Descriptors {
+	// 	fmt.Println(desc.Digest)
+	// 	fmt.Println(desc.Annotations)
+	// }
+
+	// if len(remote.Descriptors) != len(res.CacheKeys()) {
+	// 	return nil, errors.New("cache key & descriptor length mismatch")
+	// }
+
 	for i, desc := range remote.Descriptors {
 		cacheItems = append(cacheItems, earthlyInlineCacheItem{Key: res.CacheKeys()[i].Digest(), Descriptor: desc.Digest})
 	}
@@ -82,3 +93,12 @@ func earthlyInlineCacheDigests(ctx context.Context, job *solver.Job, exp exporte
 
 	return val, nil
 }
+
+func hasInlineCacheExporter(exporters []RemoteCacheExporter) bool {
+	for _, exp := range exporters {
+		if _, ok := asInlineCache(exp); ok {
+			return true
+		}
+	}
+	return false
+}

solver/llbsolver/solver.go

@@ -595,12 +595,14 @@ func (s *Solver) Solve(ctx context.Context, id string, sessionID string, req fro
 		// 	inp.AddMeta(k, v)
 		// }
 
-		meta, err := earthlyInlineCache(ctx, j, e, cached)
-		if err != nil {
-			return nil, errors.Wrap(err, "failed prepare inline cache")
-		}
-		for k, v := range meta {
-			inp.AddMeta(k, v)
+		if hasInlineCacheExporter(exp.CacheExporters) {
+			meta, err := earthlyInlineCache(ctx, j, e, cached)
+			if err != nil {
+				return nil, errors.Wrap(err, "failed prepare inline cache")
+			}
+			for k, v := range meta {
+				inp.AddMeta(k, v)
+			}
 		}
 
 		if err := inBuilderContext(ctx, j, e.Name(), j.SessionID+"-export", func(ctx context.Context, _ session.Group) error {