feat(tiller): re-use values during upgrade

When `helm install -f foo.yaml bar` is called, and then the release is
upgraded with `helm upgrade happy-panda bar`, this will now re-use the
values that were submitted with `-f foo.yaml`. The same is true for
values specified with `--set`.

Closes #1227

cmd/tiller/release_server.go

@@ -325,6 +325,16 @@ func (s *releaseServer) performUpdate(originalRelease, updatedRelease *release.R
 	return res, nil
 }
 
+// reuseValues copies values from the current release to a new release if the new release does not have any values.
+//
+// If the request already has values, or if there are no values in the current release, this does nothing.
+func (s *releaseServer) reuseValues(req *services.UpdateReleaseRequest, current *release.Release) {
+	if (req.Values == nil || req.Values.Raw == "") && current.Config != nil && current.Config.Raw != "" {
+		log.Printf("Copying values from %s (v%d) to new release.", current.Name, current.Version)
+		req.Values = current.Config
+	}
+}
+
 // prepareUpdate builds an updated release for an update operation.
 func (s *releaseServer) prepareUpdate(req *services.UpdateReleaseRequest) (*release.Release, *release.Release, error) {
 	if req.Name == "" {
@@ -341,6 +351,9 @@ func (s *releaseServer) prepareUpdate(req *services.UpdateReleaseRequest) (*rele
 		return nil, nil, err
 	}
 
+	// If new values were not supplied in the upgrade, re-use the existing values.
+	s.reuseValues(req, currentRelease)
+
 	ts := timeconv.Now()
 	options := chartutil.ReleaseOptions{
 		Name:      req.Name,

cmd/tiller/release_server_test.go

@@ -110,7 +110,7 @@ func namedReleaseStub(name string, status release.Status_Code) *release.Release
 			Status:        &release.Status{Code: status},
 		},
 		Chart:   chartStub(),
-		Config:  &chart.Config{Raw: `name = "value"`},
+		Config:  &chart.Config{Raw: `name: value`},
 		Version: 1,
 		Hooks: []*release.Hook{
 			{
@@ -568,6 +568,12 @@ func TestUpdateRelease(t *testing.T) {
 		t.Errorf("No manifest returned: %v", res.Release)
 	}
 
+	if res.Release.Config == nil {
+		t.Errorf("Got release without config: %#v", res.Release)
+	} else if res.Release.Config.Raw != rel.Config.Raw {
+		t.Errorf("Expected release values %q, got %q", rel.Config.Raw, res.Release.Config.Raw)
+	}
+
 	if len(updated.Manifest) == 0 {
 		t.Errorf("Expected manifest in %v", res)
 	}

pkg/chartutil/chartfile.go

@@ -24,7 +24,9 @@ import (
 	"k8s.io/helm/pkg/proto/hapi/chart"
 )
 
-// APIVersionV1 is the API version number for version 1.
+// ApiVersionV1 is the API version number for version 1.
+//
+// This is ApiVersionV1 instead of APIVersionV1 to match the protobuf-generated name.
 const ApiVersionV1 = "v1"
 
 // UnmarshalChartfile takes raw Chart.yaml data and unmarshals it.