KUBERNETES-1-2-應用管理
0.把kubernetes的環境先跑起來並確認狀態。
[[email protected] ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master.example.com Ready master 5h v1.11.1
node1.example.com Ready <none> 4h v1.11.1
node2.example.com Ready <none> 23s v1.11.1
1.啟動一個deployment應用控制的程式nginx-deploy。
[[email protected] ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --port=80 --replicas=1 --dry-run=true
deployment.apps/nginx-deploy created (dry run)
[[email protected] ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --port=80 --replicas=1
deployment.apps/nginx-deploy created
[
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deploy 1 1 1 0 20s
[
NAME READY STATUS RESTARTS AGE
nginx-deploy-5b595999-n75ds 1/1 Running 0 32m
[[email protected] ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE
nginx-deploy-5b595999-n75ds 1/1 Running 0 32m 10.244.2.2 node2.example.com
2.到node2.example.com上檢視硬體介面配置資訊，發現使用的是cni0網絡卡配置的網段。嘗試用curl進行訪問。注意：這裡只能在叢集內部進行訪問，叢集外目前是無法訪問的。
[[email protected] ~]# ifconfig
cni0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 10.244.2.1 netmask 255.255.255.0 broadcast 0.0.0.0
inet6 fe80::9850:b4ff:fec4:a770 prefixlen 64 scopeid 0x20<link>
ether 0a:58:0a:f4:02:01 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 8 bytes 648 (648.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[[email protected] ~]# curl 10.244.2.2
3.我們嘗試把已經建立的pod刪除。可以看到，因為設定了replicas=1，pod在被刪除後，會重新自動生成一個。不過新的pod執行的節點不同，這次是node1.example.com。
[[email protected] ~]# kubectl delete pods nginx-deploy-5b595999-n75ds
pod "nginx-deploy-5b595999-n75ds" deleted
[[email protected] ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE
nginx-deploy-5b595999-x52rk 1/1 Running 0 2m 10.244.1.2 node1.example.com
4.把deployment應用管理的nginx-deploy作為service釋出出來，--name=nginx指明名稱，--port=80指明service埠，--target-port=80指明pod埠，--protocol=TCP指明訪問協議。通過kubectl get svc檢視確認。這時，在叢集內部的節點之間是可以訪問的，但是叢集之外是無法訪問的。
[[email protected] ~]# kubectl expose deployment nginx-deploy --name=nginx --port=80 --target-port=80 --protocol=TCP
service/nginx exposed
[[email protected] ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 6h
nginx ClusterIP 10.102.51.215 <none> 80/TCP 15s
[[email protected] ~]# curl 10.102.51.215
5.kube-system空間中執行著兩個coredns的pod，kube-system的services資訊可以看到ClusterIP。或者執行一個client容器， --image=busybox指明映象，--replicas=1指明pod數量，-it 指明進入互動介面，--restart=Never指明pod關閉後不再重新生成。cat /etc/resolv.conf檢視地址解析，default.svc.cluster.local中的default是域名空間名稱。
[[email protected] ~]# kubectl get pods -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE
coredns-78fcdf6894-pzvc6 1/1 Running 0 6h 10.244.0.6 master.example.com
coredns-78fcdf6894-tg7zs 1/1 Running 0 6h 10.244.0.7 master.example.com
[[email protected] ~]# kubectl get svc -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP 6h
[[email protected] ~]# yum install bind-utils
[[email protected] ~]# kubectl run client --image=busybox --replicas=1 -it --restart=Never
If you don't see a command prompt, try pressing enter.
/ # cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local localdomain example.com
options ndots:5
/ # wget nginx
Connecting to nginx (10.102.51.215:80)
index.html 100% |************************************************************************************************| 612 0:00:00 ETA
/ # wget -O - -q http://nginx:80/
[[email protected] ~]# dig -t A nginx.default.svc.cluster.local @10.96.0.10
;; QUESTION SECTION:
;nginx.default.svc.cluster.local. IN A
;; ANSWER SECTION:
nginx.default.svc.cluster.local. 5 IN A 10.102.51.215
6.這時我們嘗試將pod刪除，系統會自動重新生成一個pod，我們在之前的互動介面繼續嘗試訪問nginx，依然可以訪問。
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 17m
nginx-deploy-5b595999-x52rk 1/1 Running 0 47m
[[email protected] ~]# kubectl delete pods nginx-deploy-5b595999-x52rk
pod "nginx-deploy-5b595999-x52rk" deleted
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 17m
nginx-deploy-5b595999-tj8ms 1/1 Running 0 24s
/ # wget -O - -q http://nginx:80/
7.kubectl describe svc nginx檢視服務詳細資訊，Endpoints表示的容器變化時，會通過Selector: run=nginx-deploy自動去關聯新生成的pod。 kubectl get pods --show-labels可以檢視pod的標籤資訊。我們將nginx服務刪除，然後再次釋出，在之前的互動埠依然可以訪問nginx。通過kubectl describe deployment nginx-deploy也能顯示標籤資訊Labels: run=nginx-deploy。
[[email protected] ~]# kubectl describe svc nginx
Name: nginx
Namespace: default
Labels: run=nginx-deploy
Annotations: <none>
Selector: run=nginx-deploy
Type: ClusterIP
IP: 10.102.51.215
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.3:80
Session Affinity: None
Events: <none>
[[email protected] ~]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
client 1/1 Running 0 23m run=client
nginx-deploy-5b595999-tj8ms 1/1 Running 0 5m pod-template-hash=16151555,run=nginx-deploy
[[email protected] ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7h
nginx ClusterIP 10.102.51.215 <none> 80/TCP 41m
[[email protected] ~]# kubectl delete svc nginx
service "nginx" deleted
[[email protected] ~]# kubectl expose deployment nginx-deploy --name=nginx
service/nginx exposed
[[email protected] ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7h
nginx ClusterIP 10.101.146.21 <none> 80/TCP 11s
/ # wget -O - -q http://nginx:80/
[[email protected] ~]# kubectl describe deployment nginx-deploy
Name: nginx-deploy
Namespace: default
CreationTimestamp: Fri, 07 Dec 2018 03:14:33 -0500
Labels: run=nginx-deploy
Annotations: deployment.kubernetes.io/revision=1
Selector: run=nginx-deploy
Replicas: 1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: run=nginx-deploy
Containers:
nginx-deploy:
Image: nginx:1.14-alpine
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Progressing True NewReplicaSetAvailable
Available True MinimumReplicasAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deploy-5b595999 (1/1 replicas created)
Events: <none>
8.kubectl run myapp起一個deployment，--image=ikubernetes/myapp:v1 --replicas=2指明映象和pod數量，可以在之前的互動終端對pod的地址進行訪問。將deployment釋出service為myapp，可以對service進行訪問。
[[email protected] ~]# kubectl run myapp --image=ikubernetes/myapp:v1 --replicas=2
deployment.apps/myapp created
[[email protected] ~]# kubectl get deployment
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
myapp 2 2 2 1 1m
nginx-deploy 1 1 1 1 1h
[[email protected] ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE
client 1/1 Running 0 49m 10.244.2.3 node2.example.com
myapp-848b5b879b-hgww4 1/1 Running 0 2m 10.244.2.5 node2.example.com
myapp-848b5b879b-th7kc 1/1 Running 0 2m 10.244.1.5 node1.example.com
nginx-deploy-5b595999-tj8ms 1/1 Running 0 31m 10.244.1.3 node1.example.com
/ # wget -O - -q 10.244.1.5
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
/ # wget -O - -q 10.244.2.5
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
/ # wget -O - -q 10.244.1.5/hostname.html
myapp-848b5b879b-th7kc
/ # wget -O - -q 10.244.2.5/hostname.html
myapp-848b5b879b-hgww4
[[email protected] ~]# kubectl expose deployment myapp --name=myapp --port=80
service/myapp exposed
[[email protected] ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7h
myapp ClusterIP 10.99.24.155 <none> 80/TCP 8s
nginx ClusterIP 10.101.146.21 <none> 80/TCP 23m
/ # wget -O - -q myapp/hostname.html
myapp-848b5b879b-hgww4
/ # wget -O - -q myapp/hostname.html
myapp-848b5b879b-th7kc
9.可以通過kubectl scale --replicas=對deployment的pod進行動態擴容和縮容。
[[email protected] ~]# kubectl scale --replicas=5 deployment myapp
deployment.extensions/myapp scaled
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 1h
myapp-848b5b879b-757ng 1/1 Running 0 21s
myapp-848b5b879b-hgww4 1/1 Running 0 13m
myapp-848b5b879b-lq9q5 1/1 Running 0 21s
myapp-848b5b879b-m22vb 1/1 Running 0 21s
myapp-848b5b879b-th7kc 1/1 Running 0 13m
nginx-deploy-5b595999-tj8ms 1/1 Running 0 43m
[[email protected] ~]# kubectl scale --replicas=3 deployment myapp
deployment.extensions/myapp scaled
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 1h
myapp-848b5b879b-757ng 1/1 Running 0 1m
myapp-848b5b879b-hgww4 1/1 Running 0 14m
myapp-848b5b879b-th7kc 1/1 Running 0 14m
nginx-deploy-5b595999-tj8ms 1/1 Running 0 43m
10.kubectl set image deployment可以設定deployment的映象更新，kubectl rollout status將 deployment的更新狀態輸出。kubectl rollout undo deployment可以實現回滾，如果不指定引數，回滾到最近一個版本。
[[email protected] ~]# kubectl set image deployment myapp myapp=ikubernetes/myapp:v2
deployment.extensions/myapp image updated
[[email protected] ~]# kubectl rollout status deployment myapp
Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "myapp" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "myapp" rollout to finish: 1 old replicas are pending termination...
deployment "myapp" successfully rolled out
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 1h
myapp-74c94dcb8c-bvsm5 1/1 Running 0 1m
myapp-74c94dcb8c-xkz2x 1/1 Running 0 1m
myapp-74c94dcb8c-zngl9 1/1 Running 0 1m
nginx-deploy-5b595999-tj8ms 1/1 Running 0 52m
[[email protected] ~]# kubectl rollout undo deployment myapp
deployment.extensions/myapp
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 1h
myapp-848b5b879b-7h254 1/1 Running 0 11s
myapp-848b5b879b-d7rjs 1/1 Running 0 13s
myapp-848b5b879b-wv5cz 1/1 Running 0 14s
nginx-deploy-5b595999-tj8ms 1/1 Running 0 54m
11.kubectl edit svc可以修改服務配置檔案引數type: ClusterIP --》type: Node Port，來讓物理機可以訪問service。這裡可以看到自動轉發的埠為31601/TCP，嘗試在物理機上進行訪問，可以訪問網頁。
[[email protected] ~]# kubectl edit svc myapp
service/myapp edited
type: ClusterIP --》type: Node Port
[[email protected] ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7h
myapp NodePort 10.99.24.155 <none> 80:31601/TCP 26m
nginx ClusterIP 10.101.146.21 <none> 80/TCP 50m