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k8s-pod的容器类型

news 2025/10/1 10:28:24

k8s-pod的容器类型

一、init 容器
二、pause 容器
三、sidecar 容器

一、init 容器

初始化容器像常规应用容器一样，只有一点不同：初始化容器必须在应用容器启动前运行完成

[root@k8s-1 pod]# cat init.yaml 
apiVersion: v1
kind: Pod
metadata:name: myapp-podlabels:app.kubernetes.io/name: MyApp
spec:containers:- name: myapp-containerimage: busybox:1.28command: ['sh', '-c', 'echo The app is running! && sleep 3600']initContainers:- name: init-myserviceimage: busybox:1.28command: ['sh', '-c', "until nslookup myservice.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for myservice; sleep 2; done"]- name: init-mydbimage: busybox:1.28command: ['sh', '-c', "until nslookup mydb.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for mydb; sleep 2; done"]

由于集群中尚未创建 myservice 和 mydb 这两个 Service，导致 nslookup 失败，初始化容器会持续打印 waiting for myservice 并等待

[root@k8s-1 pod]# kubectl apply -f init.yaml 
pod/myapp-pod created
[root@k8s-1 pod]# kubectl get pod
NAME                               READY   STATUS      RESTARTS   AGE
myapp-pod                          0/1     Init:0/2    0          6s

创建service

[root@k8s-1 pod]# cat service.yaml 
---
apiVersion: v1
kind: Service
metadata:name: myservice
spec:ports:- protocol: TCPport: 80targetPort: 9376
---
apiVersion: v1
kind: Service
metadata:name: mydb
spec:ports:- protocol: TCPport: 80targetPort: 9377[root@k8s-1 pod]# kubectl apply -f service.yaml 
service/myservice created
service/mydb created
[root@k8s-1 pod]# kubectl get services
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP   3d1h
mydb         ClusterIP   10.99.6.65      <none>        80/TCP    18s
myservice    ClusterIP   10.109.68.252   <none>        80/TCP    18s
[root@k8s-1 pod]# kubectl get pod
NAME                               READY   STATUS      RESTARTS   AGE
myapp-pod                          1/1     Running     0          7m2s

初始化容器检测到服务可用后完成初始化，主容器成功启动并进入运行状态

二、pause 容器

Pause 容器（也称为 “Infra 容器”）是每个 Pod 中都会最先创建的一个特殊容器，它不运行任何业务逻辑，而是作为 Pod 中所有容器的 “基础容器”，负责为整个 Pod 提供共享的网络命名空间和 PID 命名空间

docker ps 中可以看到很多的 “/pause”

三、sidecar 容器

像主容器的 “副驾驶”，与主容器共享 Pod 的网络和存储，提供非业务性的辅助功能，且与主容器同时启动、同时退出

[root@k8s-1 pod]# cat sidecar-1.yaml 
apiVersion: v1
kind: Pod
metadata:name: counter
spec:containers:- name: countimage: busybox:1.28args:- /bin/sh- -c- >i=0;while true;doecho "$i: $(date)" >> /var/log/1.log;echo "$(date) INFO $i" >> /var/log/2.log;i=$((i+1));sleep 1;done      volumeMounts:- name: varlogmountPath: /var/logvolumes:- name: varlogemptyDir: {}

创建仅包含主容器的pod

[root@k8s-1 pod]# kubectl apply -f sidecar-1.yaml
pod/counter created
[root@k8s-1 pod]# kubectl get pod
NAME                               READY   STATUS      RESTARTS   AGE
counter                            1/1     Running     0          11s
myapp-pod                          1/1     Running     0          21m
# 验证
[root@k8s-1 pod]# kubectl exec -it counter -- sh
/ # cd /var/log
/var/log # ls
1.log  2.log

添加边车容器

[root@k8s-1 pod]# cat sidecar-2.yaml 
apiVersion: v1
kind: Pod
metadata:name: counter
spec:containers:- name: countimage: busybox:1.28args:- /bin/sh- -c- >i=0;while true;doecho "$i: $(date)" >> /var/log/1.log;echo "$(date) INFO $i" >> /var/log/2.log;i=$((i+1));sleep 1;done      volumeMounts:- name: varlogmountPath: /var/log- name: count-log-1image: busybox:1.28args: [/bin/sh, -c, 'tail -n+1 -F /var/log/1.log']volumeMounts:- name: varlogmountPath: /var/log- name: count-log-2image: busybox:1.28args: [/bin/sh, -c, 'tail -n+1 -F /var/log/2.log']volumeMounts:- name: varlogmountPath: /var/logvolumes:- name: varlogemptyDir: {}

验证功能

[root@k8s-1 pod]# kubectl apply -f sidecar-2.yaml 
The Pod "counter" is invalid: spec.containers: Forbidden: pod updates may not add or remove containers
[root@k8s-1 pod]# kubectl delete -f sidecar-1.yaml 
pod "counter" deleted
[root@k8s-1 pod]# kubectl apply -f sidecar-2.yaml 
pod/counter created
[root@k8s-1 pod]# kubectl get pod
NAME                               READY   STATUS              RESTARTS   AGE
counter                            3/3     Running             0          28s
myapp-pod                          1/1     Running             0          26m
[root@k8s-1 pod]# kubectl logs counter count-log-1
0: Thu Sep 18 08:52:35 UTC 2025
1: Thu Sep 18 08:52:36 UTC 2025
2: Thu Sep 18 08:52:37 UTC 2025
3: Thu Sep 18 08:52:38 UTC 2025

删除边车容器

删除整个 Pod 后，重新创建不包含该边车容器的新 Pod

或者强制删除
在这里插入图片描述

[root@k8s-1 pod]#  kubectl delete --grace-period=0 --force  -f sidecar-2.yaml 
warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.
pod "counter" force deleted

容器重启策略（restartPolicy）