在Ubuntu 18.04 中安装和使用 mircok8s

本文实验在ubunt18.04 Server中安装 microk8s,体验单机版的kubernetes。

安装 microk8s

1. 查看可用的microk8s版本信息，在命令行执行:

snap info microk8s

系统输出:

name:      microk8s
summary:   Kubernetes for workstations and appliances
publisher: Canonical✓
contact:   https://github.com/ubuntu/microk8s
license:   Apache-2.0
description: |
  MicroK8s is a small, fast, secure, single node Kubernetes that installs on just about any Linux
  box. Use it for offline development, prototyping, testing, or use it on a VM as a small, cheap,
  reliable k8s for CI/CD. It's also a great k8s for appliances - develop your IoT apps for k8s and
  deploy them to MicroK8s on your boxes.
snap-id: EaXqgt1lyCaxKaQCU349mlodBkDCXRcg
channels:
  stable:         v1.15.2         2019-08-05 (743) 192MB classic
  candidate:      v1.15.3         2019-08-20 (778) 171MB classic
  beta:           v1.15.3         2019-08-20 (778) 171MB classic
  edge:           v1.15.3         2019-09-04 (826) 171MB classic
  1.16/stable:    –                                      
  1.16/candidate: –                                      
  1.16/beta:      v1.16.0-beta.1  2019-08-23 (799) 173MB classic
  1.16/edge:      v1.16.0-alpha.3 2019-08-23 (798) 173MB classic
  1.15/stable:    v1.15.2         2019-08-06 (745) 192MB classic
  ...

可以看到，当前的版本 1.15.2.

2. 安装

执行命令:

sudo snap install microk8s --classic

系统输出:

microk8s v1.15.2 from Canonical✓ installed

表示安装成功。

查看 microk8s 的状态

执行:

microk8s.status

系统显示：

microk8s is running
addons:
knative: disabled
jaeger: disabled
fluentd: disabled
gpu: disabled
storage: disabled
registry: disabled
rbac: disabled
ingress: disabled
dns: disabled
metrics-server: disabled
linkerd: disabled
prometheus: disabled
istio: disabled
dashboard: disabled

可以看到，所有的 addon 现在都是停止的。

开启必要的服务

我们首先开启 dashboard 和 dns 服务， 执行:

microk8s.enable dashboard

系统显示

Applying manifest
secret/kubernetes-dashboard-certs created
serviceaccount/kubernetes-dashboard created
role.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
deployment.apps/kubernetes-dashboard created
service/kubernetes-dashboard created
service/monitoring-grafana created
service/monitoring-influxdb created
service/heapster created
deployment.extensions/monitoring-influxdb-grafana-v4 created
serviceaccount/heapster created
clusterrolebinding.rbac.authorization.k8s.io/heapster created
configmap/heapster-config created
configmap/eventer-config created
deployment.extensions/heapster-v1.5.2 created

If RBAC is not enabled access the dashboard using the default token retrieved with:

token=$(microk8s.kubectl -n kube-system get secret | grep default-token | cut -d " " -f1)
microk8s.kubectl -n kube-system describe secret $token

In an RBAC enabled setup (microk8s.enable RBAC) you need to create a user with restricted
permissions as shown in https://github.com/kubernetes/dashboard/wiki/Creating-sample-user

接着执行:

microk8s.enable dns

系统显示:

Enabling DNS
Applying manifest
serviceaccount/coredns created
configmap/coredns created
deployment.apps/coredns created
service/kube-dns created
clusterrole.rbac.authorization.k8s.io/coredns created
clusterrolebinding.rbac.authorization.k8s.io/coredns created
Restarting kubelet
[sudo] password for stu: 
DNS is enabled

在执行过程中会提示需要管理员用户的密码。

获取当前所有的命名空间

执行:

microk8s.kubectl get all --all-namespaces

系统显示:

NAMESPACE     NAME                                                  READY   STATUS              RESTARTS   AGE
kube-system   pod/coredns-f7867546d-r62q2                           0/1     ContainerCreating   0          3m3s
kube-system   pod/heapster-v1.5.2-6b794f77c8-hwwfx                  0/4     ContainerCreating   0          5m43s
kube-system   pod/kubernetes-dashboard-7d75c474bb-2jxpm             0/1     ContainerCreating   0          5m45s
kube-system   pod/monitoring-influxdb-grafana-v4-6b6954958c-g6g9q   0/2     ContainerCreating   0          5m44s


NAMESPACE     NAME                           TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                  AGE
default       service/kubernetes             ClusterIP   10.152.183.1     <none>        443/TCP                  3h2m
kube-system   service/heapster               ClusterIP   10.152.183.69    <none>        80/TCP                   5m45s
kube-system   service/kube-dns               ClusterIP   10.152.183.10    <none>        53/UDP,53/TCP,9153/TCP   3m3s
kube-system   service/kubernetes-dashboard   ClusterIP   10.152.183.215   <none>        443/TCP                  5m46s
kube-system   service/monitoring-grafana     ClusterIP   10.152.183.123   <none>        80/TCP                   5m46s
kube-system   service/monitoring-influxdb    ClusterIP   10.152.183.66    <none>        8083/TCP,8086/TCP        5m46s


NAMESPACE     NAME                                             READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   deployment.apps/coredns                          0/1     1            0           3m3s
kube-system   deployment.apps/heapster-v1.5.2                  0/1     1            0           5m44s
kube-system   deployment.apps/kubernetes-dashboard             0/1     1            0           5m46s
kube-system   deployment.apps/monitoring-influxdb-grafana-v4   0/1     1            0           5m45s

NAMESPACE     NAME                                                        DESIRED   CURRENT   READY   AGE
kube-system   replicaset.apps/coredns-f7867546d                           1         1         0       3m3s
kube-system   replicaset.apps/heapster-v1.5.2-6b794f77c8                  1         1         0       5m44s
kube-system   replicaset.apps/kubernetes-dashboard-7d75c474bb             1         1         0       5m45s
kube-system   replicaset.apps/monitoring-influxdb-grafana-v4-6b6954958c   1         1         0       5m45s