feat(*): install DM

cmd/helm.go

@@ -4,6 +4,7 @@ import (
 	"os"
 
 	"github.com/codegangsta/cli"
+	"github.com/deis/helm-dm/format"
 )
 
 var version = "0.0.1"
@@ -24,7 +25,18 @@ func commands() []cli.Command {
 			Name:        "install",
 			Usage:       "Initialize the client and install DM on Kubernetes.",
 			Description: ``,
-			Action:      func(c *cli.Context) { install() },
+			Flags: []cli.Flag{
+				cli.BoolFlag{
+					Name:  "dry-run",
+					Usage: "Show what would be installed, but don't install anything.",
+				},
+			},
+			Action: func(c *cli.Context) {
+				if err := install(c.Bool("dry-run")); err != nil {
+					format.Error(err.Error())
+					os.Exit(1)
+				}
+			},
 		},
 		{
 			Name: "target",

cmd/install.go

@@ -1,13 +1,25 @@
 package main
 
 import (
+	"errors"
+
 	"github.com/deis/helm-dm/dm"
 	"github.com/deis/helm-dm/format"
 	"github.com/deis/helm-dm/kubectl"
 )
 
-func install() error {
-	runner := &kubectl.PrintRunner{}
+var ErrAlreadyInstalled error = errors.New("Already Installed")
+
+func install(dryRun bool) error {
+	var runner kubectl.Runner
+	if dryRun {
+		runner = &kubectl.PrintRunner{}
+	} else {
+		runner = &kubectl.RealRunner{}
+		if dm.IsInstalled(runner) {
+			return ErrAlreadyInstalled
+		}
+	}
 	out, err := dm.Install(runner)
 	if err != nil {
 		format.Error("Error installing: %s %s", out, err)

dm/install.go

@@ -1,6 +1,7 @@
 package dm
 
 import (
+	"github.com/deis/helm-dm/format"
 	"github.com/deis/helm-dm/kubectl"
 )
 
@@ -13,6 +14,18 @@ func Install(runner kubectl.Runner) (string, error) {
 	return string(o), 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
+	// we know that we have both the namespace and the manager API server.
+	out, err := runner.GetByKind("rc", "manager-rc", "dm")
+	if err != nil {
+		format.Error("Installation not found: %s %s", out, err)
+		return false
+	}
+	return true
+}
+
 // InstallYAML is the installation YAML for DM.
 const InstallYAML = `
 ######################################################################

kubectl/get.go

@@ -13,6 +13,17 @@ func (r RealRunner) Get(stdin []byte, ns string) ([]byte, error) {
 	return cmd.CombinedOutput()
 }
 
+func (r RealRunner) GetByKind(kind, name, ns string) (string, error) {
+	args := []string{"get", kind, name}
+
+	if ns != "" {
+		args = append([]string{"--namespace=" + ns}, args...)
+	}
+	cmd := command(args...)
+	o, err := cmd.CombinedOutput()
+	return string(o), err
+}
+
 // Get returns the commands to kubectl
 func (r PrintRunner) Get(stdin []byte, ns string) ([]byte, error) {
 	args := []string{"get", "-f", "-"}
@@ -25,3 +36,13 @@ func (r PrintRunner) Get(stdin []byte, ns string) ([]byte, error) {
 
 	return []byte(cmd.String()), nil
 }
+
+func (r PrintRunner) GetByKind(kind, name, ns string) (string, error) {
+	args := []string{"get", kind, name}
+
+	if ns != "" {
+		args = append([]string{"--namespace=" + ns}, args...)
+	}
+	cmd := command(args...)
+	return cmd.String(), nil
+}

kubectl/kubectl.go

@@ -13,6 +13,13 @@ type Runner interface {
 	Delete(string, string, string) ([]byte, error)
 	// Get returns Kubernetes resources
 	Get([]byte, string) ([]byte, error)
+
+	// GetByKind gets an entry by kind, name, and namespace.
+	//
+	// If name is omitted, all entries of that kind are returned.
+	//
+	// If NS is omitted, the default NS is assumed.
+	GetByKind(kind, name, ns string) (string, error)
 }
 
 // RealRunner implements Runner to execute kubectl commands