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 feature

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

cmd/kind/create/cluster/createcluster.go

@@ -19,6 +19,7 @@ package cluster
 
 import (
 	"fmt"
+	"time"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -33,6 +34,7 @@ type flagpole struct {
 	Config    string
 	ImageName string
 	Retain    bool
+	Wait      time.Duration
 }
 
 // NewCommand returns a new cobra.Command for cluster creation
@@ -50,6 +52,7 @@ 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().DurationVar(&flags.Wait, "wait", time.Duration(0), "Wait for control plane node to be ready (default 0s)")
 	return cmd
 }
 
@@ -81,7 +84,7 @@ 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)
 	}
 

docs/user/user-guide.md

@@ -35,6 +35,11 @@ For a sample kind configuration file see
 To use a kind configuration file use the `--config` flag and pass the path to
 the file.
 
+If you want the `create cluster` command to block until the control plane
+reaches a ready status, you can use the `--wait` flag and specify a timeout.
+To use `--wait` you must specify the units of the time to wait. For example, to
+wait for 30 seconds, do `--wait 30s`, for 5 minutes do `--wait 5m`, etc.
+
 
 ## Building Images
 

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.
+	waitForReady time.Duration // Wait for the control plane 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 bool, wait time.Duration) 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,
+		waitForReady: wait,
 	}
 
 	fmt.Printf("Creating cluster '%s' ...\n", c.ClusterName())
@@ -349,6 +351,14 @@ func (cc *createContext) provisionControlPlane(
 		}
 	}
 
+	// Wait for the control plane node to reach Ready status.
+	isReady := nodes.WaitForReady(node, time.Now().Add(cc.waitForReady))
+	if cc.waitForReady > 0 {
+		if !isReady {
+			log.Warn("timed out waiting for control plane to be ready")
+		}
+	}
+
 	return kubeadmConfig, nil
 }
 

pkg/cluster/nodes/nodes.go

@@ -19,6 +19,7 @@ package nodes
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/pkg/errors"
 	"sigs.k8s.io/kind/pkg/cluster/consts"
@@ -99,3 +100,37 @@ func list(visit func(string, *Node), filters ...string) error {
 	}
 	return nil
 }
+
+// WaitForReady uses kubectl inside the "node" container to check if the
+// control plane nodes are "Ready".
+func WaitForReady(node *Node, until time.Time) bool {
+	return tryUntil(until, func() bool {
+		cmd := node.Command(
+			"kubectl",
+			"--kubeconfig=/etc/kubernetes/admin.conf",
+			"get",
+			"nodes",
+			"--selector=node-role.kubernetes.io/master",
+			// When the node reaches status ready, the status field will be set
+			// to true.
+			"-o=jsonpath='{.items..status.conditions[-1:].status}'",
+		)
+		lines, err := exec.CombinedOutputLines(cmd)
+		if err != nil {
+			return false
+		}
+
+		// 'lines' will return the status of all nodes labeled as master. For
+		// example, if we have three control plane nodes, and all are ready,
+		// then the status will have the following format: `True True True'.
+		status := strings.Fields(lines[0])
+		for _, s := range status {
+			// Check node status. If node is ready then this wil be 'True',
+			// 'False' or 'Unkown' otherwise.
+			if !strings.Contains(s, "True") {
+				return false
+			}
+		}
+		return true
+	})
+}