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@kita-atsushi

kube-ansibleを使って自端末にkubernetesクラスターを構築する

Last updated at Posted at 2019-04-17

はじめに

こんなあなた

  • 自端末(macOS)に練習用のkubenetesが欲しい
  • minikube や k8s playgroundあるけどkubernetesの運用知りたいので複数nodeが良い
  • 自分で１からインストール手順や自動でインストールするプログラムを作りたくない

awesome-kubernetesに紹介されていた kairen/kube-ansibleを使ってみます。

事前準備

  • README通りにbrew で sshpass.rbを入れます
$ brew install http://git.io/sshpass.rb
  • ansibleをインストールします
$ brew install ansible

・ansible.cfgのhost_key_checkingの設定を消す
https://github.com/kairen/kube-ansible/blob/master/ansible.cfg#L12
https://github.com/kairen/kube-ansible/blob/master/ansible.cfg#L1７

構築してみる

README通りにシェルを動かしてみるとy/n聞かれます。
ここでは以下としました。

  1. OSをcentos7
  2. ifaceをenp0s8
  3. CNIをflannel(defaultはcalico)

上記3.を変更するには hack/setup-vms を一部修正します。


:

role_config "vip_address:.*" "vip_address: ${SUBNET}.9" ${GROUP_VARS_PATH}
+ role_config "container_network:.*" "container_network: ${CNI_PLUGIN}" ${GROUP_VARS_PATH}

# Create inventory and hosts
set_inventory

$ export OS_IMAGE="centos7"
$ export ETH="enp0s8"
$ export CNI_PLUGIN="flannel"

$ ./hack/setup-vms
Cluster Size: 1 master, 2 worker.
  VM Size: 1 vCPU, 2048 MB
  VM Info: centos7, virtualbox
  CNI binding iface: enp0s8
Start to deploy?(y): y

: (vagrant の VM立ち上げとAnsibleによるkubernetes installが始まる)

TASK [k8s-cni : Apply Kubernetes CNI] ******************************************
Wednesday 17 April 2019  20:38:42 +0900 (0:00:00.916)       0:06:57.559 *******
changed: [172.16.35.10 -> 172.16.35.10]


PLAY RECAP *********************************************************************
172.16.35.10               : ok=158  changed=91   unreachable=0    failed=0
172.16.35.11               : ok=61   changed=36   unreachable=0    failed=0
172.16.35.12               : ok=59   changed=36   unreachable=0    failed=0

起動しました。

Kubernetesを動かす

vagrant sshでmaster nodeに乗り込んでkubectlコマンドを打ってみます。
下記から rootユーザのホームディレクトリに .kube ディレクトリがあるので、rootになってkubectlが打てそうです。

$ vagrnat ssh k8s-m1
[vagrant@k8s-m1 ~]$ sudo su -
[root@k8s-m1 ~]# ls -la
total 36
dr-xr-x---.  4 root root  199 Apr 17 11:44 .
dr-xr-xr-x. 18 root root  239 Apr 17 11:29 ..
-rw-------.  1 root root 2352 Aug 23  2017 anaconda-ks.cfg
drwx------.  3 root root   17 Apr 17 11:31 .ansible
-rw-------.  1 root root    5 Apr 17 11:44 .bash_history
-rw-r--r--.  1 root root   18 Dec 29  2013 .bash_logout
-rw-r--r--.  1 root root  176 Dec 29  2013 .bash_profile
-rw-r--r--.  1 root root  176 Dec 29  2013 .bashrc
-rw-r--r--.  1 root root  100 Dec 29  2013 .cshrc
drwxr-xr-x.  4 root root   51 Apr 17 11:36 .kube
-rw-------.  1 root root 1677 Aug 23  2017 original-ks.cfg
-rw-------.  1 root root 1024 Apr 17 11:32 .rnd
-rw-r--r--.  1 root root  129 Dec 29  2013 .tcshrc

[root@k8s-m1 ~]# kubectl get all
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   9m10s
[root@k8s-m1 ~]#
[root@k8s-m1 ~]# kubectl get all --all-namespaces
NAMESPACE     NAME                                      READY   STATUS    RESTARTS   AGE
kube-system   pod/coredns-896d9f87d-5g5ls               1/1     Running   0          32m
kube-system   pod/coredns-896d9f87d-bz9zr               1/1     Running   0          35m
kube-system   pod/coredns-autoscaler-58784cd54d-x5dks   1/1     Running   0          35m
kube-system   pod/kube-apiserver-k8s-m1                 1/1     Running   0          34m
kube-system   pod/kube-controller-manager-k8s-m1        1/1     Running   0          35m
kube-system   pod/kube-flannel-ds-9sn9r                 1/1     Running   1          33m
kube-system   pod/kube-flannel-ds-kvxkl                 1/1     Running   1          33m
kube-system   pod/kube-flannel-ds-wrqlv                 1/1     Running   1          33m
kube-system   pod/kube-haproxy-k8s-m1                   1/1     Running   0          34m
kube-system   pod/kube-keepalived-k8s-m1                1/1     Running   0          35m
kube-system   pod/kube-proxy-k9wgd                      1/1     Running   0          33m
kube-system   pod/kube-proxy-qhwrw                      1/1     Running   0          33m
kube-system   pod/kube-proxy-wqtxm                      1/1     Running   0          33m
kube-system   pod/kube-scheduler-k8s-m1                 1/1     Running   0          34m

NAMESPACE     NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE
default       service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP                  36m
kube-system   service/kube-dns     ClusterIP   10.96.0.10   <none>        53/UDP,53/TCP,9153/TCP   35m

NAMESPACE     NAME                             DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
kube-system   daemonset.apps/kube-flannel-ds   3         3         3       3            3           <none>          33m
kube-system   daemonset.apps/kube-proxy        3         3         3       3            3           <none>          35m

NAMESPACE     NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   deployment.apps/coredns              2/2     2            2           35m
kube-system   deployment.apps/coredns-autoscaler   1/1     1            1           35m

NAMESPACE     NAME                                            DESIRED   CURRENT   READY   AGE
kube-system   replicaset.apps/coredns-896d9f87d               2         2         2       35m
kube-system   replicaset.apps/coredns-autoscaler-58784cd54d   1         1         1       35m

nginxを動かしてみる

# cat <<EOF >deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
EOF
# kubectl apply -f deploy.yaml
deployment.apps/nginx created

# cat <<EOF >svc.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  selector:
    app: nginx
  ports:
  - port: 80
EOF
# kubectl apply -f svc.yaml
service/nginx created

# kubectl get svc,po
NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP   75m
service/nginx        ClusterIP   10.100.167.11   <none>        80/TCP    27m

NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-7db75b8b78-c8572   1/1     Running   0          27m
pod/nginx-7db75b8b78-pc6l8   1/1     Running   0          27m
pod/nginx-7db75b8b78-xqfc7   1/1     Running   0          27m


# kubectl run alpine -it --rm --image alpine -- ash

/ # wget 10.100.167.11 && cat index.html
Connecting to 10.100.167.11 (10.100.167.11:80)
index.html           100% |************************************************************************************************|   612  0:00:00 ETA
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

動いた。

参考: 構築成功までに出会ったトラシュー

・エラー1: host_key_checking = False の重複でAnsibleエラー

以下を消して再実行します。
https://github.com/kairen/kube-ansible/blob/master/ansible.cfg#L12

Error reading config file (kube-ansible/ansible.cfg): While reading from '<string>' [line 17]: option 'host_key_checking' in section 'defaults' already exists
Ansible failed to complete successfully. Any error output should be
visible above. Please fix these errors and try again.

＄ ./hack/clear-vms
＄ ./hack/setup-vms

・エラー2: eth1がない

setup-vms を実行する前に正しいiface名を指定します。
vagrant ssh でログインし、ip aコマンド等でiface名を確認します。

TASK [k8s-setup : Copy Keepalived manifest and config files into cluster] ******
Wednesday 17 April 2019  20:16:05 +0900 (0:00:00.725)       0:01:58.900 *******
fatal: [172.16.35.10]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'ansible.vars.hostvars.HostVarsVars object' has no attribute 'ansible_eth1'"}
	to retry, use: --limit @/kube-ansible/cluster.retry

以上

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