feat(dm install): use template to generate manifest

Closes #306.

cmd/helm/dm.go

@@ -48,9 +48,28 @@ func dmCmd() cli.Command {
 						Name:  "dry-run",
 						Usage: "Show what would be installed, but don't install anything.",
 					},
+					cli.StringFlag{
+						Name:   "resourcifier-image",
+						Usage:  "The full image name of the Docker image for resourcifier.",
+						EnvVar: "HELM_RESOURCIFIER_IMAGE",
+					},
+					cli.StringFlag{
+						Name:   "expandybird-image",
+						Usage:  "The full image name of the Docker image for expandybird.",
+						EnvVar: "HELM_EXPANDYBIRD_IMAGE",
+					},
+					cli.StringFlag{
+						Name:   "manager-image",
+						Usage:  "The full image name of the Docker image for manager.",
+						EnvVar: "HELM_MANAGER_IMAGE",
+					},
 				},
 				Action: func(c *cli.Context) {
-					if err := install(c.Bool("dry-run")); err != nil {
+					dry := c.Bool("dry-run")
+					ri := c.String("resourcifier-image")
+					ei := c.String("expandybird-image")
+					mi := c.String("manager-image")
+					if err := install(dry, ei, mi, ri); err != nil {
 						format.Err("%s (Run 'helm doctor' for more information)", err)
 						os.Exit(1)
 					}
@@ -104,12 +123,17 @@ func dmCmd() cli.Command {
 	}
 }
 
-func install(dryRun bool) error {
+func install(dryRun bool, ebImg, manImg, resImg string) error {
 	runner := getKubectlRunner(dryRun)
 
-	out, err := dm.Install(runner)
+	i := dm.NewInstaller()
+	i.Manager["Image"] = manImg
+	i.Resourcifier["Image"] = resImg
+	i.Expandybird["Image"] = ebImg
+
+	out, err := i.Install(runner)
 	if err != nil {
-		format.Err("Error installing: %s %s", out, err)
+		return err
 	}
 	format.Msg(out)
 	return nil

pkg/dm/install.go

@@ -1,19 +1,58 @@
 package dm
 
 import (
+	"bytes"
+	"text/template"
+
+	"github.com/Masterminds/sprig"
 	"github.com/kubernetes/deployment-manager/pkg/format"
 	"github.com/kubernetes/deployment-manager/pkg/kubectl"
 )
 
+// Installer is capable of installing DM into Kubernetes.
+//
+// See InstallYAML.
+type Installer struct {
+	// TODO: At some point we could transform these from maps to structs.
+
+	// Expandybird params are used to render the expandybird manifest.
+	Expandybird map[string]interface{}
+	// Resourcifier params are used to render the resourcifier manifest.
+	Resourcifier map[string]interface{}
+	// Manager params are used to render the manager manifest.
+	Manager map[string]interface{}
+}
+
+// NewInstaller creates a new Installer.
+func NewInstaller() *Installer {
+	return &Installer{
+		Expandybird:  map[string]interface{}{},
+		Resourcifier: map[string]interface{}{},
+		Manager:      map[string]interface{}{},
+	}
+}
+
 // Install uses kubectl to install the base DM.
 //
 // Returns the string output received from the operation, and an error if the
 // command failed.
-func Install(runner kubectl.Runner) (string, error) {
-	o, err := runner.Create([]byte(InstallYAML))
+func (i *Installer) Install(runner kubectl.Runner) (string, error) {
+	b, err := i.expand()
+	if err != nil {
+		return "", err
+	}
+
+	o, err := runner.Create(b)
 	return string(o), err
 }
 
+func (i *Installer) expand() ([]byte, error) {
+	var b bytes.Buffer
+	t := template.Must(template.New("manifest").Funcs(sprig.TxtFuncMap()).Parse(InstallYAML))
+	err := t.Execute(&b, i)
+	return b.Bytes(), err
+}
+
 // IsInstalled checks whether DM has been installed.
 func IsInstalled(runner kubectl.Runner) bool {
 	// Basically, we test "all-or-nothing" here: if this returns without error
@@ -88,7 +127,7 @@ spec:
     spec:
       containers:
       - env: []
-        image: gcr.io/dm-k8s-testing/expandybird:latest
+        image: {{default "gcr.io/dm-k8s-testing/expandybird:latest" .Expandybird.Image}}
         name: expandybird
         ports:
         - containerPort: 8080
@@ -132,7 +171,7 @@ spec:
     spec:
       containers:
       - env: []
-        image: gcr.io/dm-k8s-testing/resourcifier:latest
+        image: {{ default "gcr.io/dm-k8s-testing/resourcifier:latest" .Resourcifier.Image }}
         name: resourcifier
         ports:
         - containerPort: 8080
@@ -176,7 +215,7 @@ spec:
     spec:
       containers:
       - env: []
-        image: gcr.io/dm-k8s-testing/manager:latest
+        image: {{ default "gcr.io/dm-k8s-testing/manager:latest" .Manager.Image }}
         name: manager
         ports:
         - containerPort: 8080