feat(tiller): add upgrade validations to tiller

cmd/helm/upgrade.go

@@ -70,12 +70,15 @@ func runUpgrade(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	_, err = helm.UpdateRelease(args[0], chartPath, rawVals, upgradeDryRun)
+	res, err := helm.UpdateRelease(args[0], chartPath, rawVals, upgradeDryRun)
 	if err != nil {
 		return prettyError(err)
 	}
 
-	fmt.Println("Coming SOON to a Helm near YOU!")
+	newVersion := res.GetRelease().Version
+	fmt.Printf("I know you want to upgrade your release to version %v.\nHang tight. We're still working on the helm upgrade command.", newVersion)
+
+	fmt.Println("\nComing soon to a Helm near YOU!")
 
 	return nil
 }

cmd/tiller/release_server.go

@@ -174,7 +174,54 @@ func (s *releaseServer) GetReleaseContent(c ctx.Context, req *services.GetReleas
 }
 
 func (s *releaseServer) UpdateRelease(c ctx.Context, req *services.UpdateReleaseRequest) (*services.UpdateReleaseResponse, error) {
-	return nil, errNotImplemented
+	rel, err := s.prepareUpdate(req)
+	if err != nil {
+		return nil, err
+	}
+
+	// TODO: perform update
+
+	return &services.UpdateReleaseResponse{Release: rel}, nil
+}
+
+// prepareUpdate builds a release for an update operation.
+func (s *releaseServer) prepareUpdate(req *services.UpdateReleaseRequest) (*release.Release, error) {
+	if req.Name == "" {
+		return nil, errMissingRelease
+	}
+
+	if req.Chart == nil {
+		return nil, errMissingChart
+	}
+
+	// finds the non-deleted release with the given name
+	rel, err := s.env.Releases.Read(req.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	//validate chart name is same as previous release
+	givenChart := req.Chart.Metadata.Name
+	releasedChart := rel.Chart.Metadata.Name
+	if givenChart != releasedChart {
+		return nil, fmt.Errorf("Given chart, %s, does not match chart originally released, %s", givenChart, releasedChart)
+	}
+
+	// validate new chart version is higher than old
+	givenChartVersion := req.Chart.Metadata.Version
+	releasedChartVersion := rel.Chart.Metadata.Version
+	if givenChartVersion <= releasedChartVersion {
+		return nil, fmt.Errorf("Given chart (%s-%v) must be a higher version than released chart (%s-%v)", givenChart, givenChartVersion, releasedChart, releasedChartVersion)
+	}
+
+	// Store an updated release.
+	updatedRelease := &release.Release{
+		Name:    req.Name,
+		Chart:   req.Chart,
+		Config:  req.Values,
+		Version: rel.Version + 1,
+	}
+	return updatedRelease, nil
 }
 
 func (s *releaseServer) uniqName(start string) (string, error) {