Resolved merge in README

pkg/cache/cache.go

@@ -18,6 +18,7 @@ package cache
 
 import (
 	"fmt"
+	"path"
 
 	"github.com/GoogleContainerTools/kaniko/pkg/config"
 	"github.com/google/go-containerregistry/pkg/authn"
@@ -25,13 +26,21 @@ import (
 	"github.com/google/go-containerregistry/pkg/name"
 	"github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
-// RetrieveLayer checks the specified cache for a layer with the tag :cacheKey
-func RetrieveLayer(opts *config.KanikoOptions, cacheKey string) (v1.Image, error) {
-	cache, err := Destination(opts, cacheKey)
+type LayerCache interface {
+	RetrieveLayer(string) (v1.Image, error)
+}
+
+type RegistryCache struct {
+	Opts *config.KanikoOptions
+}
+
+func (rc *RegistryCache) RetrieveLayer(ck string) (v1.Image, error) {
+	cache, err := Destination(rc.Opts, ck)
 	if err != nil {
 		return nil, errors.Wrap(err, "getting cache destination")
 	}
@@ -50,8 +59,11 @@ func RetrieveLayer(opts *config.KanikoOptions, cacheKey string) (v1.Image, error
 	if err != nil {
 		return nil, err
 	}
-	_, err = img.Layers()
-	return img, err
+	// Force the manifest to be populated
+	if _, err := img.RawManifest(); err != nil {
+		return nil, err
+	}
+	return img, nil
 }
 
 // Destination returns the repo where the layer should be stored
@@ -68,3 +80,20 @@ func Destination(opts *config.KanikoOptions, cacheKey string) (string, error) {
 	}
 	return fmt.Sprintf("%s:%s", cache, cacheKey), nil
 }
+
+func LocalSource(opts *config.KanikoOptions, cacheKey string) (v1.Image, error) {
+	cache := opts.CacheDir
+	if cache == "" {
+		return nil, nil
+	}
+
+	path := path.Join(cache, cacheKey)
+
+	imgTar, err := tarball.ImageFromPath(path, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "getting image from path")
+	}
+
+	logrus.Infof("Found %s in local cache", cacheKey)
+	return imgTar, nil
+}

pkg/cache/warm.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cache
+
+import (
+	"fmt"
+	"path"
+
+	"github.com/GoogleContainerTools/kaniko/pkg/config"
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+func WarmCache(opts *config.WarmerOptions) error {
+	cacheDir := opts.CacheDir
+	images := opts.Images
+	logrus.Debugf("%s\n", cacheDir)
+	logrus.Debugf("%s\n", images)
+
+	for _, image := range images {
+		cacheRef, err := name.NewTag(image, name.WeakValidation)
+		if err != nil {
+			errors.Wrap(err, fmt.Sprintf("Failed to verify image name: %s", image))
+		}
+		img, err := remote.Image(cacheRef)
+		if err != nil {
+			errors.Wrap(err, fmt.Sprintf("Failed to retrieve image: %s", image))
+		}
+
+		digest, err := img.Digest()
+		if err != nil {
+			errors.Wrap(err, fmt.Sprintf("Failed to retrieve digest: %s", image))
+		}
+		cachePath := path.Join(cacheDir, digest.String())
+		err = tarball.WriteToFile(cachePath, cacheRef, img)
+		if err != nil {
+			errors.Wrap(err, fmt.Sprintf("Failed to write %s to cache", image))
+		} else {
+			logrus.Debugf("Wrote %s to cache", image)
+		}
+
+	}
+	return nil
+}