Add flag to Wait for node to reach ready state

Add --wait flag which will make kind block until the master node of the
cluster reaches a ready state.

Resolves #42

/kind bug

Signed-off-by: Jorge Alarcon Ochoa <[email protected]>

cmd/kind/create/cluster/createcluster.go

@@ -33,6 +33,7 @@ type flagpole struct {
 	Config    string
 	ImageName string
 	Retain    bool
+	Wait      bool
 }
 
 // NewCommand returns a new cobra.Command for cluster creation
@@ -50,6 +51,7 @@ func NewCommand() *cobra.Command {
 	cmd.Flags().StringVar(&flags.Config, "config", "", "path to a kind config file")
 	cmd.Flags().StringVar(&flags.ImageName, "image", "", "node docker image to use for booting the cluster")
 	cmd.Flags().BoolVar(&flags.Retain, "retain", false, "retain nodes for debugging when cluster creation fails")
+	cmd.Flags().BoolVar(&flags.Wait, "wait", false, "Wait for master node to be ready")
 	return cmd
 }
 
@@ -81,7 +83,7 @@ func runE(flags *flagpole, cmd *cobra.Command, args []string) error {
 			return fmt.Errorf("aborting due to invalid configuration")
 		}
 	}
-	if err = ctx.Create(cfg, flags.Retain); err != nil {
+	if err = ctx.Create(cfg, flags.Retain, flags.Wait); err != nil {
 		return fmt.Errorf("failed to create cluster: %v", err)
 	}
 

pkg/cluster/context.go

@@ -48,9 +48,10 @@ type Context struct {
 // createContext is a superset of Context used by helpers for Context.Create()
 type createContext struct {
 	*Context
-	status *logutil.Status
-	config *config.Config
-	retain bool // if we should retain nodes after failing to create
+	status              *logutil.Status
+	config              *config.Config
+	retain              bool // if we should retain nodes after failing to create.
+	waitForControlPlane bool // Wait for master node to be ready.
 }
 
 // similar to valid docker container names, but since we will prefix
@@ -121,16 +122,17 @@ func (c *Context) KubeConfigPath() string {
 }
 
 // Create provisions and starts a kubernetes-in-docker cluster
-func (c *Context) Create(cfg *config.Config, retain bool) error {
+func (c *Context) Create(cfg *config.Config, retain, wait bool) error {
 	// validate config first
 	if err := cfg.Validate(); err != nil {
 		return err
 	}
 
 	cc := &createContext{
-		Context: c,
-		config:  cfg,
-		retain:  retain,
+		Context:             c,
+		config:              cfg,
+		retain:              retain,
+		waitForControlPlane: wait,
 	}
 
 	fmt.Printf("Creating cluster '%s' ...\n", c.ClusterName())
@@ -349,6 +351,17 @@ func (cc *createContext) provisionControlPlane(
 		}
 	}
 
+	// Wait for control plane node to reach Ready status.
+	if cc.waitForControlPlane {
+		if !node.WaitForControlPlane(time.Now().Add(time.Second * 30)) {
+			// TODO: logging here
+			if !cc.retain {
+				nodes.Delete(*node)
+			}
+			return "", fmt.Errorf("timed out waiting for control plane to be ready")
+		}
+	}
+
 	return kubeadmConfig, nil
 }
 

pkg/cluster/nodes/node.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -224,3 +225,33 @@ func (n *Node) WriteKubeConfig(dest string) error {
 
 	return ioutil.WriteFile(dest, buff.Bytes(), 0600)
 }
+
+// WaitForControlPlane uses kubectl inside the "node" container to check if
+// the control plane node status is "Ready". The control plane node is found by
+// looking for the node containing the substring "control-plane" in its name.
+func (n *Node) WaitForControlPlane(until time.Time) bool {
+	return tryUntil(until, func() bool {
+		cmd := n.Command("kubectl", "--kubeconfig=/etc/kubernetes/admin.conf", "get", "nodes")
+		lines, err := exec.CombinedOutputLines(cmd)
+		if err != nil {
+			return false
+		}
+		if len(lines) <= 1 {
+			return false
+		}
+
+		for _, line := range lines {
+			// We assume the control plane node contains the "control-plane"
+			// substring.
+			if strings.Contains(line, "control-plane") {
+				// Each line will have the following fields:
+				// NAME STATUS ROLES AGE VERSION
+				fields := strings.Fields(line)
+				if fields[1] == "Ready" {
+					return true
+				}
+			}
+		}
+		return false
+	})
+}