feat(kubernetes): Apply

Adds apply support to the kubernetes provider.
The provider should be feature complete now

cmd/tk/provider.go

@@ -51,6 +51,19 @@ func applyCmd() *cobra.Command {
 		Short: "[Requires Provider] apply the configuration to the target",
 	}
 	cmd.Run = func(cmd *cobra.Command, args []string) {
+		raw, err := evalDict()
+		if err != nil {
+			log.Fatalln("evaluating jsonnet:", err)
+		}
+
+		desired, err := prov.Reconcile(raw)
+		if err != nil {
+			log.Fatalln("reconciling:", err)
+		}
+
+		if err := prov.Apply(desired); err != nil {
+			log.Fatalln("applying:", err)
+		}
 	}
 	return cmd
 }

pkg/provider/kubernetes/kubectl.go

@@ -107,6 +107,32 @@ func (k Kubectl) Get(namespace, kind, name string) (map[string]interface{}, erro
 	return obj, nil
 }
 
+// Apply applies the given yaml to the cluster
+func (k Kubectl) Apply(yaml string) error {
+	if err := k.setupContext(); err != nil {
+		return err
+	}
+	argv := []string{"apply",
+		"--context", k.context,
+		"-f", "-",
+	}
+	cmd := exec.Command("kubectl", argv...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	stdin, err := cmd.StdinPipe()
+	if err != nil {
+		return err
+	}
+
+	go func() {
+		fmt.Fprintln(stdin, yaml)
+		stdin.Close()
+	}()
+
+	return cmd.Run()
+}
+
 // Diff takes a desired state as yaml and returns the differences
 // to the system in common diff format
 func (k Kubectl) Diff(yaml string) (string, error) {

pkg/provider/kubernetes/kubernetes.go

@@ -57,8 +57,12 @@ func (k *Kubernetes) Fmt(state interface{}) (string, error) {
 }
 
 // Apply receives a state object generated using `Reconcile()` and may apply it to the target system
-func (k *Kubernetes) Apply(desired interface{}) error {
-	panic("not implemented")
+func (k *Kubernetes) Apply(state interface{}) error {
+	yaml, err := k.Fmt(state)
+	if err != nil {
+		return err
+	}
+	return client.Apply(yaml)
 }
 
 // Diff takes the desired state and returns the differences from the cluster