一、獲取資源
命令： kubectl get <資源名稱>
幫助： kubectl get --help
使用 kubectl api-resources 獲取支持的資源的完整列表。
以node資源爲例：kubectl get nodes
參數：
- -o wide 輸出格式，常用格式：json | yaml | wide；
- -w 監控輸出結果，類似tail命令的-f選項；
- --show-labels 顯示標籤；
獲取資源的詳細信息：kubectl describe node k8s-master.fhw.com
獲取集羣信息：
[root@s1 ~]# kubectl cluster-info
Kubernetes master is running at https://192.168.100.49:6443
KubeDNS is running at https://192.168.100.49:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
二、手動部署一個應用
2.1 手動創建一個控制器deployment
創建一個控制器
[root@s1 ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --replicas=1 --port=80
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/nginx-deploy created
參數：
--restart=[Always, OnFailure, Never]，pod重啓策略，Always是pod退出後總是立即重啓，Never是pod退出後不再重啓。默認是Always--command -- <cmd> <arg1> ... <argN>，指定在容器中運行的命令；--schedule="0/5 * * * ?"，創建一個Cron Job控制器。
查看deployment列表：
[root@s1 ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deploy 1/1 1 1 2m15s
控制器創建後，會自動部署Pod：
[root@s1 ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-deploy-66ff98548d-w4gn2 1/1 Running 0 11m 10.244.1.4 n1 <none> <none>
通過pod 的IP訪問pod中運行的nginx服務：
[root@s1 ~]# curl 10.244.1.4
<!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>
2.2 部署一個service
service爲pod提供一個固定訪問端點。
用法：
Usage:
kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP] [--target-port=number-or-name]
[--name=name] [--external-ip=external-ip-of-service] [--type=type] [options]
部署service
[root@s1 ~]# kubectl expose deployment nginx-deploy --port=80 --target-port=80 --protocol=TCP --type=ClusterIP
service/nginx-deploy exposed
deployment：暴露的資源類型爲控制器deployment；nginx-deploy: deployment的名稱--port=80: service的端口--target-port=80: Pod的端口--type="": service類型有ClusterIP, NodePort, LoadBalancer, or ExternalName. Default is 'ClusterIP'.
--ClusterIP：表示這個service只能在羣集內部訪問，不能在集羣外部訪問；
--NodePort：表示可以在集羣外部訪問到；
獲取service列表：
[root@s1 ~]# kubectl get svc -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 10d <none>
nginx-deploy ClusterIP 10.106.115.124 <none> 80/TCP 113s run=nginx-deploy
通過service IP 訪問pod中的nginx服務：
[root@s1 ~]# curl 10.106.115.124
<!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>
運行一個客戶端Pod，在客戶端Pod內部通過service的名稱去訪問nginx服務：
[root@s1 ~]# kubectl run client -it --image=busybox --replicas=1 --restart=Never
If you don't see a command prompt, try pressing enter.
/ # wget nginx-deploy
Connecting to nginx-deploy (10.106.115.124:80)
saving to 'index.html'
index.html 100% |****************************************************************************************************| 612 0:00:00 ETA
'index.html' saved
service通過label去關聯pod：
[root@s1 ~]# kubectl describe svc nginx
Name: nginx-deploy
Namespace: default
Labels: run=nginx-deploy
Annotations: <none>
Selector: run=nginx-deploy
Type: ClusterIP
IP: 10.106.115.124
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.4:80
Session Affinity: None
Events: <none>
這時你刪除這個關聯的pod，控制器會立即啓動一個新pod，並且關聯至名爲nginx這個service。
2.3 動態擴縮容Pod副本
先創建一個新應用，叫myapp：
[root@s1 ~]# kubectl run myapp --image=ikubernetes/myapp:v1 --replicas=2
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
[root@s1 ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
myapp-7c468db58f-4zqd7 1/1 Running 0 4m1s 10.244.1.6 n1 <none> <none>
myapp-7c468db58f-w6bqf 1/1 Running 0 4m1s 10.244.2.3 n2 <none> <none>
nginx-deploy-66ff98548d-w4gn2 1/1 Running 0 119m 10.244.1.4 n1 <none> <none>
在第2.2節創建的客戶端Pod中通過ip訪問新建的應用myapp：
[root@s1 ~]# kubectl run client -it --image=busybox --replicas=1 --restart=Never
If you don't see a command prompt, try pressing enter.
/ # wget -O - -q 10.244.1.6/hostname.html
myapp-7c468db58f-4zqd7
/ # wget -O - -q 10.244.2.3/hostname.html
myapp-7c468db58f-w6bqf
兩個Pod中的內容分別對應Pod名稱。
爲myapp創建一個service：
[root@s1 ~]# kubectl expose deployment myapp --name=myapp --port=80
service/myapp exposed
[root@s1 ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 10d
myapp ClusterIP 10.105.150.147 <none> 80/TCP 13s
nginx-deploy ClusterIP 10.106.115.124 <none> 80/TCP 108m
通過service IP 訪問myapp：
[root@s1 ~]# while true;do wget -O - -q 10.111.230.41/hostname.html; sleep 1;done
myapp-7c468db58f-8hj8g
myapp-7c468db58f-8hj8g
myapp-7c468db58f-wfhph
myapp-7c468db58f-8hj8g
myapp-7c468db58f-wfhph
myapp-7c468db58f-8hj8g
myapp-7c468db58f-wfhph
myapp-7c468db58f-8hj8g
myapp-7c468db58f-8hj8g
如圖，兩個myapp Pod做負載均衡。
將myapp擴容至5個
[root@s1 ~]# kubectl scale deployment myapp --replicas=5
deployment.apps/myapp scaled
[root@s1 ~]# while true;do wget -O - -q 10.111.230.41/hostname.html; sleep 1;done
myapp-7c468db58f-kf26d
myapp-7c468db58f-wfhph
myapp-7c468db58f-kf26d
myapp-7c468db58f-kf26d
myapp-7c468db58f-s2cn4
myapp-7c468db58f-8hj8g
myapp-7c468db58f-s2cn4
myapp-7c468db58f-fqr28
myapp-7c468db58f-wfhph
myapp-7c468db58f-wfhph
myapp-7c468db58f-fqr28
myapp-7c468db58f-kf26d
這時新增的Pod會立即加入到myapp service中接受請求。
再將myapp縮減至3個
[root@s1 ~]# kubectl scale deployment myapp --replicas=3
deployment.apps/myapp scaled
[root@s1 ~]# while true;do wget -O - -q 10.111.230.41/hostname.html; sleep 1;done
myapp-7c468db58f-wfhph
myapp-7c468db58f-fqr28
myapp-7c468db58f-fqr28
myapp-7c468db58f-8hj8g
myapp-7c468db58f-wfhph
myapp-7c468db58f-8hj8g
myapp-7c468db58f-wfhph
2.4 滾動更新
升級myapp鏡像的版本。
[root@s1 ~]# kubectl set image deployment myapp myapp=ikubernetes/myapp:v2
deployment.apps/myapp image updated
[root@s1 ~]# kubectl get deployments -o wide
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
myapp 3/3 3 3 44m myapp ikubernetes/myapp:v2 run=myapp
查看滾動更新狀態：
[root@s1 ~]# kubectl rollout status deployment myapp
deployment "myapp" successfully rolled out
[root@s1 ~]# while true;do wget -O - -q 10.111.230.41; sleep 1;done
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
myapp更新過後，pod名稱也更新了
[root@s1 ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
client 0/1 Error 0 54m 10.244.2.6 n2 <none> <none>
myapp-64758bffd4-72ms4 1/1 Running 0 34m 10.244.1.11 n1 <none> <none>
myapp-64758bffd4-b9c7j 1/1 Running 0 34m 10.244.1.12 n1 <none> <none>
myapp-64758bffd4-qb6vm 1/1 Running 0 34m 10.244.2.9 n2 <none> <none>
查看pod內容器的鏡像版本：
[root@s1 ~]# kubectl describe pod myapp-64758bffd4-72ms4
Name: myapp-64758bffd4-72ms4
Namespace: default
Priority: 0
Node: n1/192.168.100.50
Start Time: Mon, 16 Dec 2019 14:15:50 +0800
Labels: pod-template-hash=64758bffd4
run=myapp
Annotations: <none>
Status: Running
IP: 10.244.1.11
IPs:
IP: 10.244.1.11
Controlled By: ReplicaSet/myapp-64758bffd4
Containers:
myapp:
Container ID: docker://4e317de24603219331e12d5119f37d9a4a9cce46571e3a2447367f28129b6414
Image: ikubernetes/myapp:v2
Image ID: docker-pullable://ikubernetes/myapp@sha256:85a2b81a62f09a414ea33b74fb8aa686ed9b168294b26b4c819df0be0712d358
Port: <none>
Host Port: <none>
State: Running
Started: Mon, 16 Dec 2019 14:15:57 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-6hhk2 (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-6hhk2:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-6hhk2
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 35m default-scheduler Successfully assigned default/myapp-64758bffd4-72ms4 to n1
Normal Pulling 35m kubelet, n1 Pulling image "ikubernetes/myapp:v2"
Normal Pulled 35m kubelet, n1 Successfully pulled image "ikubernetes/myapp:v2"
Normal Created 35m kubelet, n1 Created container myapp
Normal Started 35m kubelet, n1 Started container myapp
2.5 動態回滾
默認回滾至上一版本
[root@s1 ~]# kubectl rollout undo deployment myapp
deployment.apps/myapp rolled back
[root@s1 ~]# while true;do wget -O - -q 10.111.230.41; sleep 1;done
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
自動擴縮容依賴於監控系統，去監控系統資源使用率，根據系統資源去判斷是否需要擴容。這個問題後續再記錄。
2.6 配置從集羣外部訪問myapp
修改service myapp的類型爲NodePort
[root@s1 ~]# kubectl edit svc myapp
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
kind: Service
metadata:
creationTimestamp: "2019-12-16T06:00:08Z"
labels:
run: myapp
name: myapp
namespace: default
resourceVersion: "30911"
selfLink: /api/v1/namespaces/default/services/myapp
uid: b200645b-d1e1-47b0-8a9d-862f7f0079ff
spec:
clusterIP: 10.111.230.41
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
run: myapp
sessionAffinity: None
type: NodePort
status:
loadBalancer: {}
查看service myapp
[root@s1 ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 11d
myapp NodePort 10.111.230.41 <none> 80:30661/TCP 55m
在集羣中每個節點上都會開啓一個30661端口（這個端口是隨機生成的），映射到K8S集羣的myapp service的80端口。可自行在其它節點驗證。
提供給集羣外部的訪問端口爲30661。
外部訪問地址：http://192.168.100.49:30661
在192.168.100.49這臺主機上驗證，如圖：
[root@s1 ~]# curl 192.168.100.49:30661
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
三個節點均可正常訪問。
如果想通過一個固定地址去訪問這個myapp，可以利用nginx做反向代理。