验证Kubernetes部署时的笔记
公式文件如下。
部署
环境
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-28T20:03:09Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"11+", GitVersion:"v1.11.5-eks-6bad6d", GitCommit:"6bad6d9c768dc0864dab48a11653aa53b5a47043", GitTreeState:"clean", BuildDate:"2018-12-06T23:13:14Z", GoVersion:"go1.10.3", Compiler:"gc", Platform:"linux/amd64"}
部署是什么？
管理多个 ReplicaSet。
Deploymnet 管理 ReplicaSets，而 ReplicaSets 管理 Pod。
通过使用 Deploymetn，可以进行滚动更新和回滚。
创建部署
使用公式文档中的以下内容。
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.15.4
ports:
- containerPort: 80
# deployment を作成
$kubectl create -f https://k8s.io/examples/controllers/nginx-deployment.yaml
deployment.apps "nginx-deployment" created
# deployments の情報を確認.3つの Pod を要求しており、3つとも起動している
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 3 3 3 3 16s
# デプロイの状態を確認.nginx-deployment が成功した事が分かる
$kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
# deployment によって replicasets が作成されている
$kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-d7b764d88 3 3 3 2m
# replicasets によって3つの pod が作成されている事が分かる.今回はラベルで app=nginx をつけているのでこれで一覧が確認できる
$ kubectl get pod -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-deployment-d7b764d88-2wr7n 1/1 Running 0 3m
nginx-deployment-d7b764d88-4zrgg 1/1 Running 0 3m
nginx-deployment-d7b764d88-9w6hz 1/1 Running 0 3m
部署的更新
尝试改变部署的形象。
# set image コマンドで変更
$kubectl set image deployment nginx-deployment nginx=nginx:1.9.1 --record
deployment.apps "nginx-deployment" image updated
# デプロイ成功
$kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
# replicasets が2つある.0 になっている方が最初にデプロイをした時の replicasets
$kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-6fdbb596db 3 3 3 1m
nginx-deployment-d7b764d88 0 0 0 11m
# どのような挙動となっていたかは describe deployments コマンドの Events からも確認できる
$kubectl describe deployments
Name: nginx-deployment
Namespace: default
CreationTimestamp: Wed, 26 Dec 2018 15:22:48 +0900
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-6fdbb596db (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 13m deployment-controller Scaled up replica set nginx-deployment-d7b764d88 to 3
Normal ScalingReplicaSet 3m deployment-controller Scaled up replica set nginx-deployment-6fdbb596db to 1
Normal ScalingReplicaSet 3m deployment-controller Scaled down replica set nginx-deployment-d7b764d88 to 2
Normal ScalingReplicaSet 3m deployment-controller Scaled up replica set nginx-deployment-6fdbb596db to 2
Normal ScalingReplicaSet 2m deployment-controller Scaled down replica set nginx-deployment-d7b764d88 to 1
Normal ScalingReplicaSet 2m deployment-controller Scaled up replica set nginx-deployment-6fdbb596db to 3
Normal ScalingReplicaSet 2m deployment-controller Scaled down replica set nginx-deployment-d7b764d88 to 0
从上述可以看出，首先将 Deployment:nginx-deployment-d7b764d88 缩放到了 3。
接下来的事件是在 Deployments 更新时进行的操作，按照顺序如下所示。
-
- 新しい ReplicaSet「nginx-deployment-6fdbb596db」を 1 にスケールアップ
-
- 古い ReplicaSet「nginx-deployment-d7b764d88」を 2 にスケールダウン
-
- 新しい ReplicaSet「nginx-deployment-6fdbb596db」を 2 にスケールアップ
-
- 古い ReplicaSet「nginx-deployment-d7b764d88」を 1 にスケールダウン
-
- 新しい ReplicaSet「nginx-deployment-6fdbb596db」を 3 にスケールアップ
- 古い ReplicaSet「nginx-deployment-d7b764d88」を 0 にスケールダウン
上述的行为将根据“RollingUpdateStrategy”的设置而改变。
目前的设置是“25％ 的最大不可用，25％ 的最大超量”。
最大不可用表示在更新过程中允许下线的 Pod，最大超量表示允许超过正常数量的 Pod。
撤销部署
首先，我们将进行NG（不可取的）的部署。
# イメージを変更
$kubectl set image deployment nginx-deployment nginx=nginx:1.999999.1 --record
deployment.apps "nginx-deployment" image updated
# デプロイメントがスタックしている
$ kubectl rollout status deployment nginx-deployment
Waiting for rollout to finish: 1 out of 3 new replicas have been updated...
# replica set 一覧を表示.nginx-deployment-77d66694fc が新規に作成された replica set のようにみえる
$kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-6fdbb596db 3 3 3 23m
nginx-deployment-77d66694fc 1 1 0 1m
nginx-deployment-d7b764d88 0 0 0 33m
# pod を確認.Image の pull に失敗している
$kubectl get pods |grep nginx-deployment-77d66694fc
nginx-deployment-77d66694fc-586kl 0/1 ImagePullBackOff 0 2m
$kubectl describe pod nginx-deployment-77d66694fc-586kl
(一部略)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 4m default-scheduler Successfully assigned default/nginx-deployment-77d66694fc-586kl to ip-172-31-19-51.ap-northeast-1.compute.internal
Normal Pulling 2m (x4 over 4m) kubelet, ip-172-31-19-51.ap-northeast-1.compute.internal pulling image "nginx:1.999999.1"
Warning Failed 2m (x4 over 4m) kubelet, ip-172-31-19-51.ap-northeast-1.compute.internal Failed to pull image "nginx:1.999999.1": rpc error: code = Unknown desc = Error response from daemon: manifest for nginx:1.999999.1 not found
Warning Failed 2m (x4 over 4m) kubelet, ip-172-31-19-51.ap-northeast-1.compute.internal Error: ErrImagePull
Warning Failed 2m (x6 over 4m) kubelet, ip-172-31-19-51.ap-northeast-1.compute.internal Error: ImagePullBackOff
Normal BackOff 2m (x7 over 4m) kubelet, ip-172-31-19-51.ap-northeast-1.compute.internal Back-off pulling image "nginx:1.999999.1"
由于发现图像的规定不好，首先要确认信息以进行回退。
# 対象 deployment の履歴を確認.初回は --record=true を指定していないので記録にない
$ kubectl rollout history deployment 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:1.999999.1 --record=true
# 特定リビジョンの詳細な確認も可能.戻す予定のリビジョンを確認
$ kubectl rollout history deployment nginx-deployment --revision 2
deployments "nginx-deployment" with revision #2
Pod Template:
Labels: app=nginx
pod-template-hash=2986615286
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>
为了回退到上一版本，我们将执行rollback undo。
# 一つ前のリビジョンに戻す
$kubectl rollout undo deployment nginx-deployment
deployment.apps "nginx-deployment"
# deployment 成功
$kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
# history を見ると指定したリビジョン2は消えて4として設定されている
$kubectl rollout history deployment nginx-deployment deployments "nginx-deployment"
REVISION CHANGE-CAUSE
1 <none>
3 kubectl set image deployment nginx-deployment nginx=nginx:1.999999.1 --record=true
4 kubectl set image deployment nginx-deployment nginx=nginx:1.9.1 --record=true
如果要将特定版本回滚，请指定 –to-revision 选项。
部署的停止和恢复
如果不想立即部署，可以暂时停止。
# 停止
$kubectl rollout pause deployment nginx-deployment
deployment.apps "nginx-deployment" paused
# ステータスでは分からず
$kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
# describe すると分かった
$kubectl describe deployment nginx-deployment |grep Pause
Progressing Unknown DeploymentPaused
尝试更新部署的映像在这个状态下。
# deployment を変更
$kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.15.4 --record=true
deployment.apps "nginx-deployment" image updated
# 待機中のままとなる
$kubectl rollout status deployment nginx-deployment
Waiting for rollout to finish: 0 out of 3 new replicas have been updated...
由于无法前进，所以重新开始。
# resume する
$kubectl rollout resume deployment nginx-deployment
deployment.apps "nginx-deployment" resumed
# デプロイ終了
$kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
