feat(repo): use OCI style digest identifiers

Use the same format as the Open Container Initiative for a digest
string. https://github.com/opencontainers/image-spec/blob/master/descriptor.md#digests-and-verification

Fixes #1166

docs/chart_repository.md

@@ -23,7 +23,7 @@ alpine-0.1.0:
   name: alpine
   url: https://storage.googleapis.com/kubernetes-charts/alpine-0.1.0.tgz
   created: 2016-05-26 11:23:44.086354411 +0000 UTC
-  checksum: a61575c2d3160e5e39abf2a5ec984d6119404b18
+  digest: sha256:78e9a4282295184e8ce1496d23987993673f38e33e203c8bc18bc838a73e5864
   chartfile:
     name: alpine
     description: Deploy a basic Alpine Linux pod
@@ -33,7 +33,7 @@ redis-2.0.0:
   name: redis
   url: https://storage.googleapis.com/kubernetes-charts/redis-2.0.0.tgz
   created: 2016-05-26 11:23:44.087939192 +0000 UTC
-  checksum: 2cea3048cf85d588204e1b1cc0674472b4517919
+  digest: sha256:bde9c2949e64d059c18d8f93566a64dafc6d2e8e259a70322fb804831dfd0b5b
   chartfile:
     name: redis
     description: Port of the replicatedservice template from kubernetes/charts

pkg/repo/index.go

@@ -39,7 +39,7 @@ type ChartRef struct {
 	URL       string          `yaml:"url"`
 	Created   string          `yaml:"created,omitempty"`
 	Removed   bool            `yaml:"removed,omitempty"`
-	Checksum  string          `yaml:"checksum,omitempty"`
+	Digest    string          `yaml:"digest,omitempty"`
 	Chartfile *chart.Metadata `yaml:"chartfile"`
 }
 

pkg/repo/repo.go

@@ -17,9 +17,10 @@ limitations under the License.
 package repo // import "k8s.io/helm/pkg/repo"
 
 import (
-	"crypto/sha1"
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
-	"fmt"
+	"io"
 	"io/ioutil"
 	"net/url"
 	"os"
@@ -131,7 +132,7 @@ func (r *ChartRepository) Index() error {
 		}
 
 		chartfile := ch.Metadata
-		hash, err := generateChecksum(path)
+		digest, err := generateDigest(path)
 		if err != nil {
 			return err
 		}
@@ -152,7 +153,7 @@ func (r *ChartRepository) Index() error {
 		url, _ := url.Parse(r.URL)
 		url.Path = filepath.Join(url.Path, key+".tgz")
 
-		entry := &ChartRef{Chartfile: chartfile, Name: chartfile.Name, URL: url.String(), Created: created, Checksum: hash, Removed: false}
+		entry := &ChartRef{Chartfile: chartfile, Name: chartfile.Name, URL: url.String(), Created: created, Digest: digest, Removed: false}
 
 		r.IndexFile.Entries[key] = entry
 
@@ -170,18 +171,15 @@ func (r *ChartRepository) Index() error {
 	return r.saveIndexFile()
 }
 
-func generateChecksum(path string) (string, error) {
+func generateDigest(path string) (string, error) {
 	f, err := os.Open(path)
 	if err != nil {
 		return "", err
 	}
 
-	b, err := ioutil.ReadAll(f)
-	if err != nil {
-		return "", err
-	}
-
-	result := sha1.Sum(b)
+	h := sha256.New()
+	io.Copy(h, f)
 
-	return fmt.Sprintf("%x", result), nil
+	digest := h.Sum([]byte{})
+	return "sha256:" + hex.EncodeToString(digest[:]), nil
 }

pkg/repo/repo_test.go

@@ -85,8 +85,8 @@ func TestIndex(t *testing.T) {
 		}
 		timestamps[chartName] = details.Created
 
-		if details.Checksum == "" {
-			t.Errorf("Checksum was not set for %s", chartName)
+		if details.Digest == "" {
+			t.Errorf("Digest was not set for %s", chartName)
 		}
 	}