以下部署過程基於官方手冊，稍作調整以便理解。
若還未搭建環境，可參考CentOS7 Kubernetes minikube本地環境搭建一文搭建環境。
本示例包含以下內容：
由於本篇內容是按實際操作順序編排，如要實踐本篇中的事例，推薦從頭到尾按順序一步步執行，以免“跳戲”。
創建Deployment
$ vim nginx-deployment.yaml
創建nginx-deployment.yaml文件，聲明deployment的各項參數，文件內容如下：
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
#指定deployment的名稱
name: nginx-deployment
labels:
app: nginx
spec:
#期望創建3個nginx實例（3個pod）
replicas: 3
selector:
#選擇label：app=nginx的pod來創建實例
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
該文件表示要創建3個pod，每個pod運行nginx1.7.9鏡像。
執行創建
$ kubectl create -f nginx-deployment.yaml $ deployment.apps "nginx-deployment" created
創建成功，查看deployment和pod的運行狀況：
$ kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 3 3 3 57s $ kubectl get po -o wide NAME READY STATUS RESTARTS AGE IP NODE nginx-deployment-75675f5897-jgl27 1/1 Running 0 12s 172.17.0.5 minikube nginx-deployment-75675f5897-rrnsk 1/1 Running 0 12s 172.17.0.7 minikube nginx-deployment-75675f5897-txlkv 1/1 Running 0 12s 172.17.0.6 minikube
可以看到deployment已經創建成功，並創建了3個pod，IP地址分別是172.17.0.5，172.17.0.6，172.17.0.7。
分別對三個IP地址使用curl命令，均能返回nginx的歡迎頁內容，表示創建成功。
$ curl http://172.17.0.5
<!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>
更新Deployment
我們將nginx:1.7.9版本更新到nginx:1.9.1。
手動設置升級的nginx版本：
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record deployment.apps "nginx-deployment" image updated
查看rollout，pod和rs狀態：
$ kubectl rollout status deploy nginx-deployment Waiting for rollout to finish: 2 out of 3 new replicas have been updated... $ kubectl get po NAME READY STATUS RESTARTS AGE nginx-deployment-75675f5897-rrnsk 1/1 Terminating 0 1m nginx-deployment-75675f5897-txlkv 0/1 Terminating 0 1m nginx-deployment-c4747d96c-bf97v 1/1 Running 0 4s nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 5s nginx-deployment-c4747d96c-rthg5 1/1 Running 0 6s $ get rs NAME DESIRED CURRENT READY AGE nginx-deployment-75675f5897 0 0 0 1m nginx-deployment-c4747d96c 3 3 3 9s
可以看到舊的pod正在被終止，新的pod被創建出來，這是滾動升級的過程。
等升級完成再來看看rollout和pod的狀態：
$ kubectl rollout status deploy nginx-deployment deployment "nginx-deployment" successfully rolled out $ kubectl get po NAME READY STATUS RESTARTS AGE nginx-deployment-c4747d96c-bf97v 1/1 Running 0 4m nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 4m nginx-deployment-c4747d96c-rthg5 1/1 Running 0 4m
可以看到已經升級完成了，依舊是3個pod。
我們可以通過describe命令查看deployment的升級過程：
$ kubectl describe deployments
Name: nginx-deployment
Namespace: default
CreationTimestamp: Mon, 31 Dec 2018 16:52:13 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision=2
kubernetes.io/change-cause=kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record=true
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: app=nginx
Containers:
nginx:
Image: nginx:1.9.1
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deployment-c4747d96c (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 12m deployment-controller Scaled up replica set nginx-deployment-75675f5897 to 3
Normal ScalingReplicaSet 10m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 1
Normal ScalingReplicaSet 10m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 2
Normal ScalingReplicaSet 10m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 2
Normal ScalingReplicaSet 10m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 1
Normal ScalingReplicaSet 10m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 3
Normal ScalingReplicaSet 10m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 0
從Event.Message這一列可以看出，滾動升級的過程就是把新的deployment的ReplicaSet設置從0慢慢上升到期望，這里也就是3，同時把舊deployment的ReplicaSet設置從3慢慢降到0。
根據RollingUpdateStrategy的設置，保證在滾動升級中可用pod的數量。
回滾Deployment
當更新失敗，或者是更新版本不穩定，k8s也可以方便的回滾到指定的歷史版本。
比如，當我們更新的時候，把1.9.1誤輸成了1.91
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.91 --record deployment.apps "nginx-deployment" image updated
查看deploy，pod和rollout狀態：
$ kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 4 1 3 45m $ kubectl get po NAME READY STATUS RESTARTS AGE nginx-deployment-595696685f-q8zrr 0/1 ImagePullBackOff 0 29s nginx-deployment-c4747d96c-bf97v 1/1 Running 0 44m nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 44m nginx-deployment-c4747d96c-rthg5 1/1 Running 0 44m $ kubectl rollout status deploy nginx-deployment Waiting for rollout to finish: 1 out of 3 new replicas have been updated...
命令kubectl rollout status deploy nginx-deployment會阻塞等待deployment更新完成，由於我們輸入了錯誤的nginx版本，無法更新完成，這條命令會一直阻塞，所以我們先CTRL+C終止執行。
UP-TO-DATE=1表示創建了一個用於更新的Pod。
從kubectl get po的結果我們得知有一個pod創建不成功。
我們再通過describe命令看一下升級不成功的pod發生了什么：
$kubectl describe po nginx-deployment-595696685f-q8zrr
Name: nginx-deployment-595696685f-q8zrr
Namespace: default
Node: minikube/192.168.0.62
Start Time: Mon, 31 Dec 2018 17:37:07 +0800
Labels: app=nginx
pod-template-hash=1512522419
Annotations: <none>
Status: Pending
IP: 172.17.0.7
Controlled By: ReplicaSet/nginx-deployment-595696685f
Containers:
nginx:
Container ID:
Image: nginx:1.91
Image ID:
Port: 80/TCP
Host Port: 0/TCP
State: Waiting
Reason: ImagePullBackOff
Ready: False
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-q244m (ro)
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
Volumes:
default-token-q244m:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-q244m
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 12m default-scheduler Successfully assigned nginx-deployment-595696685f-q8zrr to minikube
Normal SuccessfulMountVolume 12m kubelet, minikube MountVolume.SetUp succeeded for volume "default-token-q244m"
Normal Pulling 10m (x4 over 12m) kubelet, minikube pulling image "nginx:1.91"
Warning Failed 10m (x4 over 12m) kubelet, minikube Failed to pull image "nginx:1.91": rpc error: code = Unknown desc = Error response from daemon: manifest for nginx:1.91 not found
Warning Failed 10m (x4 over 12m) kubelet, minikube Error: ErrImagePull
Normal BackOff 9m (x6 over 11m) kubelet, minikube Back-off pulling image "nginx:1.91"
Warning Failed 1m (x40 over 11m) kubelet, minikube Error: ImagePullBackOff
可以看到，由於鏡像nginx:1.91是不存在的，所以pod報錯：Failed to pull image "nginx:1.91":xxxx，導致升級不成功。
通過以下命令查看升級歷史記錄，就跟svn，git差不多。
$ kubectl rollout history deploy nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 <none> 2 kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record=true 3 kubectl set image deployment/nginx-deployment nginx=nginx:1.91 --record=true
由於我們之前升級加了--record參數，可以看到升級當時所使用命令。
使用rollout history xxx --revision=n可以查看明細：
$ kubectl rollout history deploy nginx-deployment --revision=2
deployments "nginx-deployment" with revision #2
Pod Template:
Labels: app=nginx
pod-template-hash=703038527
Annotations: kubernetes.io/change-cause=kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record=true
Containers:
nginx:
Image: nginx:1.9.1
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
用undo操作回滾：
$ kubectl rollout undo deploy nginx-deployment deployment.apps "nginx-deployment"
或者使用--to-revision來回滾到指定版本：
$ kubectl rollout undo deploy nginx-deployment --to-revision=2 deployment.apps "nginx-deployment"
看一下rollout,pod,rs的狀態：
$ get deployment NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 3 3 3 1h $ kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-c4747d96c-bf97v 1/1 Running 0 1h nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 1h nginx-deployment-c4747d96c-rthg5 1/1 Running 0 1h $ kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-595696685f 0 0 0 1h nginx-deployment-75675f5897 0 0 0 1h nginx-deployment-c4747d96c 3 3 3 1h $ kubectl rollout status deploy nginx-deployment deployment "nginx-deployment" successfully rolled out
回滾成功。
describe查看一下deployment：
$ kubectl describe deploy nginx-deployment
Name: nginx-deployment
Namespace: default
CreationTimestamp: Mon, 31 Dec 2018 16:52:13 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision=4
kubernetes.io/change-cause=kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record=true
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: app=nginx
Containers:
nginx:
Image: nginx:1.9.1
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deployment-c4747d96c (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal DeploymentRollback 4m deployment-controller Rolled back deployment "nginx-deployment" to revision 2
Normal ScalingReplicaSet 4m deployment-controller Scaled down replica set nginx-deployment-595696685f to 0
從Events.Message中得知，deployment-controller將版本回滾到revision 2了。
Deployment擴容和縮容
Deployment擴容縮容的本質其實就是改變ReplicaSet的數量來控制Pod的數量，增加就是擴容，縮小就是縮容。
擴容
假設我們要將nginx從3個pod擴展到10個pod：
$ kubectl scale deploy nginx-deployment --replicas=10 deployment.extensions "nginx-deployment" scaled
查看po,rs,deployment狀態：
$ kubectl get po NAME READY STATUS RESTARTS AGE nginx-deployment-c4747d96c-2zw9w 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-bf97v 1/1 Running 0 2h nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 2h nginx-deployment-c4747d96c-fr6b6 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-grgr6 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-hh9tk 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-pdz4q 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-rthg5 1/1 Running 0 2h nginx-deployment-c4747d96c-rvfs7 0/1 ContainerCreating 0 2s nginx-deployment-c4747d96c-s5mrc 0/1 ContainerCreating 0 2s $ kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-595696685f 0 0 0 1h nginx-deployment-75675f5897 0 0 0 2h nginx-deployment-c4747d96c 10 10 7 2h $ kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 10 10 10 10 2h
可以看到，pod已經從3個變成10個了，這里pod的狀態還在啟動中，啟動完成之后10個pod都將會是Running狀態。
縮容
假設我們要將nginx從10個pod減少為3個：
$ kubectl scale deploy nginx-deployment --replicas=3 deployment.extensions "nginx-deployment" scaled $ kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 3 3 3 2h $ kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-595696685f 0 0 0 1h nginx-deployment-75675f5897 0 0 0 2h nginx-deployment-c4747d96c 3 3 3 2h $ kubeget po NAME READY STATUS RESTARTS AGE nginx-deployment-c4747d96c-2zw9w 1/1 Terminating 0 3m nginx-deployment-c4747d96c-bf97v 1/1 Running 0 2h nginx-deployment-c4747d96c-ctpl2 1/1 Running 0 2h nginx-deployment-c4747d96c-hh9tk 1/1 Terminating 0 3m nginx-deployment-c4747d96c-pdz4q 0/1 Terminating 0 3m nginx-deployment-c4747d96c-rthg5 1/1 Running 0 2h
可以看到pod的數量在減少，當縮容成功之后，會只剩下3個pod。
手動擴容縮絨還不能體現k8s的精髓之處，k8s還能夠根據節點的負載情況，自動擴容縮容，這樣才能實現自動化，智能化。自動擴容的內容不在本篇中的討論范圍內。大概可能或許假以時日會寫一篇關於自動擴容的例子。
Deployment的暫停和恢復
在上述的例子中，當我們輸入更新指令之后，滾動更新就立即開始了，但有的時候，我們還需要修改其他一些配置來保證新版本的正確運行，這時就需要先暫停滾動更新，等其他配置工作完成之后，再開始滾動升級。
我們刪掉當前deployment，用初始文件重新部署一個:
$ kubectl delete deploy nginx-deployment deployment.extensions "nginx-deployment" deleted $ kubectl create -f nginx-deployment.yaml deployment.apps "nginx-deployment" created
暫停滾動更新：
$ kubectl rollout pause deploy nginx-deployment deployment.apps "nginx-deployment" paused
我們將當前的1.9.1版本“升級”成1.7.9：
$ kubectl set image deploy nginx-deployment nginx=nginx:1.7.9 deployment.apps "nginx-deployment" image updated
查看rollout history
$ kubectl rollout history deploy nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 <none>
我們發現由於我們使用rollout pause暫停了滾動更新，該deployment並沒有更新。
繼續修改配置，完成更新操作：
$ kubectl set resources deploy nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi deployment.apps "nginx-deployment" resource requirements updated $ kubectl rollout resume deploy nginx-deployment deployment.apps/nginx-deployment resumed
配置完之后查看pod狀態：
$ kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-6d95f89565-7wgrb 0/1 Pending 0 2m nginx-deployment-75675f5897-9pqz5 1/1 Running 0 18m nginx-deployment-75675f5897-mdclm 1/1 Running 0 18m nginx-deployment-75675f5897-vf4lw 1/1 Running 0 18m
發現第一個Pod一直處於Pending狀態，這劇本好像不太對…
有了前面describe查看deployment升級失敗的例子，這里我們舉一反三一下：
$ kubectl describe pod nginx-deployment-6d95f89565-7wgrb
Name: nginx-deployment-6d95f89565-7wgrb
Namespace: default
Node: <none>
Labels: app=nginx
pod-template-hash=2851945121
Annotations: <none>
Status: Pending
IP:
Controlled By: ReplicaSet/nginx-deployment-6d95f89565
Containers:
nginx:
Image: nginx:1.7.9
Port: 80/TCP
Host Port: 0/TCP
Limits:
cpu: 200m
memory: 512Mi
Requests:
cpu: 200m
memory: 512Mi
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-q244m (ro)
Conditions:
Type Status
PodScheduled False
Volumes:
default-token-q244m:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-q244m
Optional: false
QoS Class: Guaranteed
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
---- ------ ---- ---- -------
Warning FailedScheduling 4s (x12 over 2m) default-scheduler 0/1 nodes are available: 1 Insufficient cpu.
看到Events知道了，是我的服務器太渣了，分配不起200m的cpu資源，那就分配少一些，重新分配一下：
$ kubectl set resources deploy nginx-deployment -c=nginx --limits=cpu=20m,memory=256Mi deployment.apps "nginx-deployment" resource requirements updated
等一陣子等pod啟動完畢：
$ kubectl get po NAME READY STATUS RESTARTS AGE nginx-deployment-6b58c6db49-n9jmf 1/1 Running 0 20s nginx-deployment-6b58c6db49-rbwxw 1/1 Running 0 22s nginx-deployment-6b58c6db49-rklg2 1/1 Running 0 17s
現在能正常更新完成了。
用Service暴露Deployment
到目前為止，上述deployment所生產的Pod都只能被Node內部訪問，而且而且每次pod擴容，縮容或者是升級之后，IP地址均可能改變。我們用service將deployment暴露出去，讓k8s外部的應用也可以訪問：
$ kubectl expose deploy nginx-deployment --type=NodePort --name=nginx --port=80 service "nginx" exposed
使用get svc查看服務：
$ kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 21h nginx NodePort 10.111.219.247 <none> 80:31302/TCP 13s
這時候外部應用就可以使用31302這個端口來訪問內部的包含nginx的pod了。
這里就不着重介紹service了，service的內容就留到下一篇吧。