Deployment
2023-12-04
Deployment
Deployment 资源类型：
# nginx-deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
namespace: default
labels:
app: deployment # 此处标签是标记这个 Deployment 的，并不会与下方的 Pod 关联
spec:
replicas: 3 # 期望的 Pod 副本数量，默认值为1
selector: # Label Selector，必须匹配 Pod 模板中的标签，通过这个标签关联下方 Pod 的标签
matchLabels:
app: nginx
template: # Pod 模板
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
ports: # 端口类型没有实际作用，只是用作显示
- containerPort: 80
创建这个资源对象：
[root@kube01 ~]# kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx created
通过标签可以过滤查看 Pod
[root@kube01 ~]# kubectl get pod -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-74d589986c-64rpq 1/1 Running 0 4m41s
nginx-74d589986c-h9w46 1/1 Running 0 4m41s
nginx-74d589986c-kz2mc 1/1 Running 0 4m41s
通过 describe 找一个 Pod 查看一下，发现 Pod 的 Controlled By 是 ReplicaSet
[root@kube01 ~]# kubectl describe pod nginx-74d589986c-64rpq
Name: nginx-74d589986c-64rpq
Namespace: default
Priority: 0
Node: kube02/192.168.17.6
Start Time: Mon, 12 Jun 2023 14:56:35 +0800
Labels: app=nginx
pod-template-hash=74d589986c
Annotations: <none>
Status: Running
IP: 172.30.1.12
IPs:
IP: 172.30.1.12
Controlled By: ReplicaSet/nginx-74d589986c
Containers:
nginx:
Container ID: docker://930f0e3d2f16d2a6060efa8a44ace81a1c81baf2999fef106e207588a759561e
Image: nginx
Image ID: docker-pullable://nginx@sha256:0d17b565c37bcbd895e9d92315a05c1c3c9a29f762b011a10c54a66cd53c9b31
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 12 Jun 2023 14:57:14 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-t8wsn (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-t8wsn:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 7m39s default-scheduler Successfully assigned default/nginx-74d589986c-64rpq to kube02
Normal Pulling 7m37s kubelet Pulling image "nginx"
Normal Pulled 6m59s kubelet Successfully pulled image "nginx" in 37.872905558s
Normal Created 6m59s kubelet Created container nginx
Normal Started 6m59s kubelet Started container nginx
再查看一下 ReplicaSet 发现 Controlled By 属于 Deployment，说明 Deployment 不直接参与 Pod 的控制。
[root@kube01 ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-74d589986c 3 3 3 9m46s
[root@kube01 ~]# kubectl describe rs nginx-74d589986c
Name: nginx-74d589986c
Namespace: default
Selector: app=nginx,pod-template-hash=74d589986c
Labels: app=nginx
pod-template-hash=74d589986c
Annotations: deployment.kubernetes.io/desired-replicas: 3
deployment.kubernetes.io/max-replicas: 4
deployment.kubernetes.io/revision: 1
Controlled By: Deployment/nginx
Replicas: 3 current / 3 desired
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
Labels: app=nginx
pod-template-hash=74d589986c
Containers:
nginx:
Image: nginx
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulCreate 9m57s replicaset-controller Created pod: nginx-74d589986c-64rpq
Normal SuccessfulCreate 9m57s replicaset-controller Created pod: nginx-74d589986c-kz2mc
Normal SuccessfulCreate 9m57s replicaset-controller Created pod: nginx-74d589986c-h9w46
通过观察发现，控制方式为 Deployment -> ReplicaSet -> Pod
水平伸缩
通过 kubectl 的 scale 快捷命令扩容副本数量为 4 个，查看发现 deployment 的数据已经改为 4 个
[root@kube01 ~]# kubectl scale deployment nginx --replicas=4
deployment.apps/nginx scaled
[root@kube01 ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx 4/4 4 4 25m
再次查看 ReplicaSet， 发现 ReplicaSet 也变成了 4 个
[root@kube01 ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-74d589986c 4 4 4 25m
再次查看 Pod， 发现 Pod 也变成了 4 个
[root@kube01 ~]# kubectl get pod -l app=nginx
NAME READY STATUS RESTARTS AGE
nginx-74d589986c-64rpq 1/1 Running 0 28m
nginx-74d589986c-h9w46 1/1 Running 0 28m
nginx-74d589986c-kz2mc 1/1 Running 0 28m
nginx-74d589986c-rm759 1/1 Running 0 4m19s
滚动更新
Deployment 支持滚动更新RollingUpdate，就是所谓的新增一个，删除一个循环执行，保持 Pod 永远有可用状态的，这种适用于版本之间的切换。
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
namespace: default
labels:
app: deployment
spec:
replicas: 3
selector:
matchLabels:
app: nginx
minReadySeconds: 5
strategy:
type: RollingUpdate # 指定更新策略：RollingUpdate和Recreate
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
minReadySeconds：表示 Kubernetes 在等待设置的时间后才进行升级，如果没有设置该值，Kubernetes 会假设该容器启动起来后就提供服务了，如果没有设置该值，在某些极端情况下可能会造成服务不正常运行，默认值就是0。type=RollingUpdate：表示设置更新策略为滚动更新，可以设置为Recreate和RollingUpdate两个值，Recreate表示全部重新创建，默认值就是RollingUpdate。maxSurge：表示升级过程中最多可以比原先设置多出的 Pod 数量，例如：maxSurage=1，replicas=5，就表示Kubernetes 会先启动一个新的 Pod，然后才删掉一个旧的 Pod，整个升级过程中最多会有5+1个 Pod。maxUnavaible：表示升级过程中最多有多少个 Pod 处于无法提供服务的状态，当maxSurge不为0时，该值也不能为0，例如：maxUnavaible=1，则表示 Kubernetes 整个升级过程中最多会有1个 Pod 处于无法服务的状态。
通过更新部署文件实现滚动更新
[root@kube01 ~]# kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx configured
通过 watch 滚动更新的状态，会发现滚动更新的一个现状
[root@kube01 ~]# kubect rollout status deployment/nginx -w
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "nginx" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "nginx" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "nginx" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "nginx" rollout to finish: 2 of 3 updated replicas are available...
Waiting for deployment "nginx" rollout to finish: 2 of 3 updated replicas are available...
deployment "nginx" successfully rolled out
通过滚动更新可以通过 pause 与 resume，进行暂停、恢复的操作。
[root@kube01 ~]# kubectl rollout pause deployment/nginx
deployment.apps/nginx paused
[root@kube01 ~]# kubectl rollout resume deployment/nginx
deployment.apps/nginx resumed
在滚动更新时通过 describe 查看 deployment 信息，发现存在OldReplicaSets与NewReplicaSet状态，判断出滚动更新是新建一个 ReplicaSet，删除OldReplicaSet 里的一个副本，再新建一个NewReplicaSet里的一个副本，知道更新完成为止。
[root@kube01 ~]# kubectl describe deployment nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 12 Jun 2023 15:57:06 +0800
Labels: app=deployment
Annotations: deployment.kubernetes.io/revision: 4
Selector: app=nginx
Replicas: 3 desired | 3 updated | 4 total | 3 available | 1 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 5
RollingUpdateStrategy: 1 max unavailable, 1 max surge
Pod Template:
Labels: app=nginx
Containers:
nginx:
Image: nginx:1.7.9
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing Unknown DeploymentPaused
OldReplicaSets: nginx-74d589986c (1/1 replicas created)
NewReplicaSet: nginx-5fcc5d8c6d (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 8m14s deployment-controller Scaled up replica set nginx-74d589986c to 3
Normal ScalingReplicaSet 7m1s deployment-controller Scaled up replica set nginx-5fcc5d8c6d to 1
Normal ScalingReplicaSet 6m39s deployment-controller Scaled up replica set nginx-5fcc5d8c6d to 3
Normal ScalingReplicaSet 6m22s deployment-controller Scaled down replica set nginx-74d589986c to 0
Normal ScalingReplicaSet 4m16s deployment-controller Scaled down replica set nginx-5fcc5d8c6d to 2
Normal ScalingReplicaSet 4m16s deployment-controller Scaled up replica set nginx-74d589986c to 1
Normal ScalingReplicaSet 26s (x2 over 7m1s) deployment-controller Scaled up replica set nginx-5fcc5d8c6d to 2
Normal ScalingReplicaSet 26s (x2 over 7m1s) deployment-controller Scaled down replica set nginx-74d589986c to 2
Normal ScalingReplicaSet 18s (x2 over 6m39s) deployment-controller Scaled down replica set nginx-74d589986c to 1
Normal ScalingReplicaSet 18s (x6 over 4m16s) deployment-controller (combined from similar events): Scaled up replica set nginx-5fcc5d8c6d to 3
再查看 ReplicaSet 后发现，确实有两个 ReplicaSet
[root@kube01 ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-5fcc5d8c6d 3 3 3 8m42s
nginx-74d589986c 0 0 0 9m55s
滚动更新的 deployment 有历史记录，通过 history 查看历史记录，通过 revision 可以查看历史版本
[root@kube01 ~]# kubectl rollout history deployment nginx
deployment.apps/nginx
REVISION CHANGE-CAUSE
3 <none>
4 <none>
可以指定 reversion 查看历史版本信息
[root@kube01 ~]# kubectl rollout history deployment nginx --revision=3
deployment.apps/nginx with revision #3
Pod Template:
Labels: app=nginx
pod-template-hash=74d589986c
Containers:
nginx:
Image: nginx
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
假如现在要直接回退到当前版本的前一个版本，我们可以直接使用如下命令进行操作：
[root@kube01 ~]# kubectl rollout undo deployment nginx
deployment.apps/nginx rolled back
也可以指定版本回退
[root@kube01 ~]# kubectl rollout undo deployment nginx --to-revision=4
deployment.apps/nginx rolled back