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第 11 屆 iThome 鐵人賽
DAY 17
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DevOps

Kubernetes的30天養成計劃系列 第 17 篇

[Day17] k8s管理篇（三）：User Management、RBAC、Node Ｍaintenance

11th鐵人賽
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前言

今天是管理篇的最後一篇，我們最後要介紹User Management和RBAC，就是使用者的權限操作，如：新增使用者、設置對應權限，以及Node Maintenance，也就是相對應的集群節點管理方式，底下詳細介紹。

User Management與RBAC

這邊我們直接給範例，來快速測試一下，會比較好了解

新增一個New User

這邊的目標是，要在集群內新增nick這個使用者

我們先登入minikube的ssh

$minikube ssh
                         _             _
            _         _ ( )           ( )
  ___ ___  (_)  ___  (_)| |/')  _   _ | |_      __
/' _ ` _ `\| |/' _ `\| || , <  ( ) ( )| '_`\  /'__`\
| ( ) ( ) || || ( ) || || |\`\ | (_) || |_) )(  ___/
(_) (_) (_)(_)(_) (_)(_)(_) (_)`\___/'(_,__/'`\____)

$

新增一個RSA的金鑰

$ openssl genrsa -out nick.pem 2048
Generating RSA private key, 2048 bit long modulus
...................................+++
..........+++
e is 65537 (0x10001)
$ ls
nick.pem

產生該金鑰對應的Certificate

X.509是密碼學裡公鑰憑證的格式標準

$ openssl req -new -key nick.pem -out nick-csr.pem -subj "/CN=nick/O=myteam"
$ ls
nick-csr.pem  nick.pem
$ sudo openssl x509 -req -in nick-csr.pem -CA /var/lib/minikube/certs/ca.crt -CAkey /var/lib/minikube/certs/ca.key -CAcreateserial -out nick.crt -days 1000
Signature ok
subject=/CN=nick/O=myteam
Getting CA Private Key
$ ls
nick-csr.pem  nick.crt  nick.pem

檢查Certificate

$ cat nick.crt
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

檢查私鑰

$ cat nick.pem
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

接著跳出ssh，回到一般命令列操作

新增~/.minikube/nick.crt（就是nick.crt的內容

$vim ~/.minikube/nick.crt
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

新增~/.minikube/nick.key（就是nick.pem的內容

$vim ~/.minikube/nick.key
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

新增好這兩個檔案後，我們要下些指令：

首先我們先檢查已知的k8s的config

$kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority: /Users/nickzhuang/.minikube/ca.crt
    server: https://192.168.99.100:8443
  name: minikube
contexts:
- context:
    cluster: minikube
    user: minikube
  name: minikube
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
  user:
    client-certificate: /Users/nickzhuang/.minikube/apiserver.crt
    client-key: /Users/nickzhuang/.minikube/apiserver.key

這個內容跟~/.kube/config的內容一樣喔，可以自行檢查看看！

接著我們利用前面產生的Certificate和Key去新增使用者資訊

$kubectl config set-credentials nick --client-certificate ~/.minikube/nick.crt --client-key ~/.minikube/nick.key
User "nick" set.
$kubectl config set-context nick-context --cluster=minikube --user=nick
Context "nick-context" created.

再次檢查k8s的config，發現到Context和User區塊有增加內容

$kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority: /Users/nickzhuang/.minikube/ca.crt
    server: https://192.168.99.100:8443
  name: minikube
contexts:
- context:
    cluster: minikube
    user: minikube
  name: minikube
- context:
    cluster: minikube
    user: nick
  name: nick-context
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
  user:
    client-certificate: /Users/nickzhuang/.minikube/apiserver.crt
    client-key: /Users/nickzhuang/.minikube/apiserver.key
- name: nick
  user:
    client-certificate: /Users/nickzhuang/.minikube/nick.crt
    client-key: /Users/nickzhuang/.minikube/nick.key

檢查當前的Context，Context對應到目前的使用者，應該是minikube

$kubectl config current-context
minikube

切換使用者到nick

$kubectl config use-context nick-context
Switched to context "nick-context".

檢視集群節點狀態

$kubectl get po
Error from server (Forbidden): pods is forbidden: User "nick" cannot list resource "pods" in API group "" in the namespace "default"

它這裡是說沒有權限，不用擔心，因為我們還沒有設置，請接續下個部分

Role與RoleBinding

目前k8s支援四種模式，分別是：

  • Node：一個專用授權程序，根據計劃運行的pod為kubelet授予權限。
  • ABAC：基於屬性的訪問控制（Attribute-based access control），是一種通過將屬性組合在一起的策略，將訪問權限授予用戶的方法。
  • RBAC：基於角色的訪問控制（Role-based access control），是一種基於用戶的角色，來管理對計算機或網絡資源的訪問的方法。
  • Webhook：WebHook是一個HTTP回調，發生某些事情時會通過HTTP POST進行簡單的事件通知。

下面示範一種常用的模式RBAC，這種設定可以滿足讓不同使用者擁有不同權限的需求。

將New User綁定RBAC

延續上個部分，在這邊我們要先新增Role和RoleBinding

附帶一提，minikube要使用RBAC，必須要在集群啟動時啟用設定

$minikube start —-extra-config=apiserver.Authorization.Mode=RBAC

新增一個Role

$vim role.yaml
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: default
  name: pod-reader
rules:
- apiGroups: [""] # "" indicates the core API group
  resources: ["pods"]
  verbs: ["get", "watch", "list"]

新增一個RoleBinding

$vim role-binding.yaml
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: read-pods
  namespace: default
subjects:
- kind: User
  name: nick # Name is case sensitive
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role #this must be Role or ClusterRole
  name: pod-reader # must match the name of the Role
  apiGroup: rbac.authorization.k8s.io

因為在上個例子，我們已經切換到了nick的身份，但是因為他沒有權限，所以我們要先切換回minikube，也就是Administrator的身份

$kubectl config use-context minikube
Switched to context "minikube".

接著啟動Role和RoleBinding

$kubectl apply -f role.yaml
role.rbac.authorization.k8s.io/pod-reader created
$kubectl apply -f role-binding.yaml
rolebinding.rbac.authorization.k8s.io/read-pods created

檢查Role和RoleBinding的狀態

$kubectl get role
NAME         AGE
pod-reader   30s
$kubectl get rolebindings
NAME        AGE
read-pods   72s

詳細檢查Role和RoleBinding

$kubectl describe role pod-reader
Name:         pod-reader
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"Role","metadata":{"annotations":{},"name":"pod-reader","namespace":"default"},"rules"...
PolicyRule:
  Resources  Non-Resource URLs  Resource Names  Verbs
  ---------  -----------------  --------------  -----
  pods       []                 []              [get watch list]
$kubectl describe rolebindings.rbac.authorization.k8s.io read-pods
Name:         read-pods
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"RoleBinding","metadata":{"annotations":{},"name":"read-pods","namespace":"default"},"...
Role:
  Kind:  Role
  Name:  pod-reader
Subjects:
  Kind  Name  Namespace
  ----  ----  ---------
  User  nick

有的，可以看到New User：nick的狀態。

接著我們切換使用者到nick

$kubectl config use-context nick-context
Switched to context "nick-context".

然後我們嘗試獲取集群的Pod資訊

$kubectl get po
No resources found.

可以用了！現在使用者nick可以獲得集群的Pod資訊

測試完沒用到的可以刪掉

$kubectl delete -f role.yaml
role.rbac.authorization.k8s.io "pod-reader" deleted
$kubectl delete -f role-binding.yaml
rolebinding.rbac.authorization.k8s.io "read-pods" deleted
$kubectl get role
No resources found.
$kubectl get rolebindings.rbac.authorization.k8s.io
No resources found.

回復原狀囉～

Node Ｍaintenance

這個部分前面有稍微提過，就是關於k8s管理篇初體驗那邊，我們有稍稍操作到了一些管理Node的方法，這邊我們更進一步，來測試一下在Node管理階段的時候，在該Node上的元件會有哪些預期行為。

管理三劍客：Drain、Cordon、Uncordon

我們先編輯一個Deployment的YAML

$vim pod-deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helloworld-deployment
  labels:
    app: helloworld
spec:
  replicas: 3
  selector:
    matchLabels:
      app: helloworld
  template:
    metadata:
      labels:
        app: helloworld
    spec:
      containers:
      - name: k8s-demo
        image: 105552010/k8s-demo:v1
        ports:
        - containerPort: 3000

接著新增它到集群裡

$kubectl create -f pod-deploy.yaml
deployment.apps/helloworld-deployment created

檢查Pod狀態

$kubectl get po
NAME                                     READY   STATUS              RESTARTS   AGE
helloworld-deployment-6777fcc7f4-5vtn6   0/1     ContainerCreating   0          4s
helloworld-deployment-6777fcc7f4-99478   0/1     ContainerCreating   0          4s
helloworld-deployment-6777fcc7f4-nx9q7   0/1     ContainerCreating   0          4s
$kubectl get po
NAME                                    READY   STATUS              RESTARTS   AGE
helloworld-deployment-94d865798-d8mnx   1/1     Running             0          5s
helloworld-deployment-94d865798-ffn5c   0/1     ContainerCreating   0          5s
helloworld-deployment-94d865798-m6tp6   1/1     Running             0          5s
$kubectl get po
NAME                                    READY   STATUS    RESTARTS   AGE
helloworld-deployment-94d865798-d8mnx   1/1     Running   0          10s
helloworld-deployment-94d865798-ffn5c   1/1     Running   0          10s
helloworld-deployment-94d865798-m6tp6   1/1     Running   0          10s

OK，啟動正常，我們接續下一步

接著我們將Node設為不可調度

$kubectl drain minikube --ignore-daemonsets --delete-local-data
node/minikube already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/kube-proxy-pj4df
evicting pod "dashboard-metrics-scraper-6c554969c6-g5ftb"
evicting pod "helloworld-deployment-94d865798-m6tp6"
evicting pod "dashboard-metrics-scraper-6c554969c6-4jqkw"
evicting pod "dashboard-metrics-scraper-6c554969c6-fd7bg"
evicting pod "kubernetes-dashboard-74f5d74fd7-vkx8q"
evicting pod "kubernetes-dashboard-74f5d74fd7-fbgd2"
evicting pod "kubernetes-dashboard-74f5d74fd7-mcblb"
evicting pod "kubernetes-dashboard-74f5d74fd7-t9zv9"
evicting pod "helloworld-deployment-94d865798-d8mnx"
evicting pod "helloworld-deployment-94d865798-ffn5c"
evicting pod "kubernetes-dashboard-74f5d74fd7-c9f9t"
evicting pod "dashboard-metrics-scraper-6c554969c6-wkwvx"
evicting pod "kubernetes-dashboard-74f5d74fd7-7hlkv"
evicting pod "coredns-5644d7b6d9-smn5n"
evicting pod "coredns-5644d7b6d9-z6zgs"
evicting pod "storage-provisioner"
pod/kubernetes-dashboard-74f5d74fd7-c9f9t evicted
pod/dashboard-metrics-scraper-6c554969c6-g5ftb evicted
pod/dashboard-metrics-scraper-6c554969c6-4jqkw evicted
pod/kubernetes-dashboard-74f5d74fd7-7hlkv evicted
pod/dashboard-metrics-scraper-6c554969c6-wkwvx evicted
pod/kubernetes-dashboard-74f5d74fd7-fbgd2 evicted
pod/kubernetes-dashboard-74f5d74fd7-mcblb evicted
pod/kubernetes-dashboard-74f5d74fd7-t9zv9 evicted
pod/storage-provisioner evicted
pod/dashboard-metrics-scraper-6c554969c6-fd7bg evicted
pod/kubernetes-dashboard-74f5d74fd7-vkx8q evicted
pod/coredns-5644d7b6d9-smn5n evicted
pod/coredns-5644d7b6d9-z6zgs evicted
pod/helloworld-deployment-94d865798-ffn5c evicted
pod/helloworld-deployment-94d865798-m6tp6 evicted
pod/helloworld-deployment-94d865798-d8mnx evicted
node/minikube evicted

注意到我們之前的做法是用cordon，drain與cordon不同的是，它會在集群內找尋其他可調用的Node，並將終止的那些Pod轉移過去

不過因為現在是單節點的集群，所以看不出轉移的部分，這個部分我們會在上雲的時候再看一次，就能看出差異。

我們來看下剛剛那些Pod

$kubectl get po
NAME                                    READY   STATUS    RESTARTS   AGE
helloworld-deployment-94d865798-47gxp   0/1     Pending   0          3m7s
helloworld-deployment-94d865798-rv729   0/1     Pending   0          3m7s
helloworld-deployment-94d865798-vshxc   0/1     Pending   0          3m7s

發現到都是Pending的狀態

檢查集群Node

$kubectl get nodes
NAME       STATUS                     ROLES    AGE   VERSION
minikube   Ready,SchedulingDisabled   master   16h   v1.16.0

這個應用情境是當機器需要定期保養、維護的時候，可以先停機，等到機器恢復了，就可以繼續用

$kubectl uncordon minikube
node/minikube uncordoned
$kubectl get nodes
NAME       STATUS   ROLES    AGE   VERSION
minikube   Ready    master   16h   v1.16.0

檢查Pod狀態，顯然已經恢復正常

$kubectl get po
NAME                                    READY   STATUS    RESTARTS   AGE
helloworld-deployment-94d865798-47gxp   1/1     Running   0          6m3s
helloworld-deployment-94d865798-rv729   1/1     Running   0          6m3s
helloworld-deployment-94d865798-vshxc   1/1     Running   0          6m3s

我們把它cordon試試

$kubectl cordon minikube
node/minikube cordoned

發現Pod狀態還是沒變（已經調度的情況不影響，但後續要調度會失敗

$kubectl get po
NAME                                    READY   STATUS    RESTARTS   AGE
helloworld-deployment-94d865798-47gxp   1/1     Running   0          6m27s
helloworld-deployment-94d865798-rv729   1/1     Running   0          6m27s
helloworld-deployment-94d865798-vshxc   1/1     Running   0          6m27s

新增一個Pod

$vim pod-demo.yaml
apiVersion: v1
kind: Pod
metadata:
  name: my-helloworld
  labels:
    app: helloworld
spec:
  containers:
  - name: k8s-demo
    image: 105552010/k8s-demo
    args:
    - /bin/sh
    - -c
    - touch /tmp/healthy; npm start; sleep 60; rm -rf /tmp/healthy; sleep 600
    ports:
    - name: nodejs-port
      containerPort: 3000
    livenessProbe:
      httpGet:
        path: /
        port: 3000
      initialDelaySeconds: 15
      timeoutSeconds: 30
    readinessProbe:
      exec:
        command:
        - cat
        - /tmp/healthy
      initialDelaySeconds: 5
      periodSeconds: 5

接著調度它

$kubectl create -f pod-demo.yaml
pod/my-helloworld created

檢查集群的Pod狀態

$kubectl get po
NAME                                    READY   STATUS    RESTARTS   AGE
helloworld-deployment-94d865798-47gxp   1/1     Running   0          8m54s
helloworld-deployment-94d865798-rv729   1/1     Running   0          8m54s
helloworld-deployment-94d865798-vshxc   1/1     Running   0          8m54s
my-helloworld                           0/1     Pending   0          4s

它會一直維持Pending，因為Node已經不能調度了。

測試成功！小屁孩再度把玩耍的恢復原狀。

$kubectl delete -f pod-demo.yaml
pod "my-helloworld" deleted
$kubectl delete -f pod-deploy.yaml
deployment.apps "helloworld-deployment" deleted
$kubectl uncordon minikube
node/minikube uncordoned

檢查集群狀態

$kubectl get all
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   16h

好的，經確認已經回復初始狀態

小結

今天我們看到了使用者的管理，以及基於RBAC的集群權限控管方式，最後我們看到了管理節點的基本工具，管理三劍客：Drain、Cordon、Uncordon，我們可以透過這些工具達成我們管理節點的需求。今天管理篇就結束了，明天整合介紹一些Docker和k8s的常用套件，預計後天我們會開始介紹雲端的東西，明天見囉！

參考資料

本文同步刊載於https://github.com/x1y2z3456/ironman

感謝您撥冗閱讀此文章，不喜勿噴，有任何問題建議歡迎下方留言：）

說個笑話，希望我能寫滿30天啊（笑


上一篇
[Day16] k8s之PV小整合：Pod、Deployment、Service、Job與PersistentVolume
下一篇
[Day18] k8s之管理篇延伸：兩個H的小故事：Harbor與Helm
系列文
Kubernetes的30天養成計劃 共 30 篇
  1. 26
    [Day26] k8s管理篇延伸與EKS（二）：Resource Quota、Namespace、RBAC
  2. 27
    [Day27] k8s應用篇（一）：Helm部署apps、HPA和CA
  3. 28
    [Day28] k8s應用篇（二）：EBS和EFS的使用
  4. 29
    [Day29] k8s集群篇：HA、Federation
  5. 30
    [Day30] k8s總結：架構整合、圖表整理
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