etcd: add self hosted etcd mode

- add a feature flag that will enable self hosted etcd
- on self hosted etcd mode, create a etcd static pod have bootkube wait
until it's up

Author: hongchaodeng

cmd/bootkube/start.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/kubernetes-incubator/bootkube/pkg/bootkube"
 	"github.com/kubernetes-incubator/bootkube/pkg/util"
+	"github.com/kubernetes-incubator/bootkube/pkg/util/etcdutil"
 )
 
 var (
@@ -23,15 +24,17 @@ var (
 	}
 
 	startOpts struct {
-		assetDir   string
-		etcdServer string
+		assetDir       string
+		etcdServer     string
+		selfHostedEtcd bool
 	}
 )
 
 func init() {
 	cmdRoot.AddCommand(cmdStart)
 	cmdStart.Flags().StringVar(&startOpts.etcdServer, "etcd-server", "http://127.0.0.1:2379", "Single etcd node to use during bootkube bootstrap process.")
 	cmdStart.Flags().StringVar(&startOpts.assetDir, "asset-dir", "", "Path to the cluster asset directory. Expected layout genereted by the `bootkube render` command.")
+	cmdStart.Flags().BoolVar(&startOpts.selfHostedEtcd, "experimental-self-hosted-etcd", false, "Self hosted etcd mode. Includes starting the initial etcd member by bootkube.")
 }
 
 func runCmdStart(cmd *cobra.Command, args []string) error {
@@ -40,6 +43,13 @@ func runCmdStart(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("Invalid etcd etcdServer %q: %v", startOpts.etcdServer, err)
 	}
 
+	// TODO: this should likely move into bootkube.Run() eventually.
+	if startOpts.selfHostedEtcd {
+		if err := etcdutil.StartEtcd(); err != nil {
+			return fmt.Errorf("fail to start etcd: %v", err)
+		}
+	}
+
 	bk, err := bootkube.NewBootkube(bootkube.Config{
 		AssetDir:   startOpts.assetDir,
 		EtcdServer: etcdServer,

pkg/util/etcdutil/start_etcd.go

@@ -0,0 +1,64 @@
+package etcdutil
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"github.com/golang/glog"
+)
+
+func StartEtcd() error {
+	if err := ioutil.WriteFile("/etc/kubernetes/manifests/boot-etcd.yaml", []byte(etcdPodYaml), 0600); err != nil {
+		return fmt.Errorf("fail to write file '/etc/kubernetes/manifests/boot-etcd.yaml': %v", err)
+	}
+	glog.Info("etcd server has been defined to run by kubelet. Please wait...")
+	return waitEtcdUp()
+}
+
+func waitEtcdUp() error {
+	httpcli := &http.Client{
+		Timeout: 10 * time.Second,
+	}
+	for {
+		_, err := httpcli.Get("http://127.0.0.1:2379/version")
+		if err != nil {
+			glog.Infof("couldn't talk to etcd server (retrying 10s later): %v\n", err)
+			time.Sleep(10 * time.Second)
+			continue
+		}
+		break
+	}
+	return nil
+}
+
+var etcdPodYaml = `apiVersion: v1
+kind: Pod
+metadata:
+  name: boot-etcd
+  namespace: kube-system
+spec:
+  containers:
+  - command:
+    - /bin/sh
+    - -c
+    - /usr/local/bin/etcd
+      --name boot-etcd
+      --listen-client-urls=http://0.0.0.0:2379
+      --listen-peer-urls=http://0.0.0.0:2380
+      --advertise-client-urls=http://$(MY_POD_IP):2379
+      --initial-advertise-peer-urls http://$(MY_POD_IP):2380
+      --initial-cluster boot-etcd=http://$(MY_POD_IP):2380
+      --initial-cluster-token bootkube
+      --initial-cluster-state new
+      --data-dir=/var/etcd/data
+    env:
+      - name: MY_POD_IP
+        valueFrom:
+          fieldRef:
+            fieldPath: status.podIP
+    image: quay.io/coreos/etcd:v3.1.0-alpha.1
+    name: etcd
+  hostNetwork: true
+`