InitContainers
InitContainers
InitContainers 类型的对象是在 Pod 中的应用容器之前运行的一个或多个容器。启动容器可以包含应用程序映像中没有的实用程序或配置脚本。
- 启动容器总是运行到完成为止。
- 每个 init 容器必须在下一个容器开始之前成功完成。
如果 Pod 的 init 容器失败，Kubernetes 会反复重启 Pod，直到 init 容器成功。但是，如果 Pod 的 restartPolicy 如何 Never，Kubernetes 将不会重启 Pod，主容器也不会运行。
$ vim nginx-initcontainer.yaml
apiVersion : v1
kind : Pod
metadata :
name : init-demo
spec :
containers :
- name : nginx
image : nginx
ports :
- containerPort : 80
volumeMounts :
- name : workdir
mountPath : / usr / share / nginx / html
initContainers :
- name : install
image : busybox
command : ['wget', '-O', '/work-dir/index.html', 'http://linuxtips.io']
volumeMounts :
- name : workdir
mountPath : " / work-dir "
dnsPolicy : Default
volumes :
- name : workdir
emptyDir : {}
然后从清单中创建 Pod：
$ kubectl create -f nginx-initcontainer.yaml
pod/init-demo created
$ kubectl exec -ti init-demo -- cat /usr/share/nginx/html/index.html
$ kubectl describe pod init-demo
Name: init-demo
Namespace: default
Priority: 0
PriorityClassName: <none>
Node: k8s3/172.31.28.13
Start Time: Sun, 11 Nov 2018 13:10:02 +0000
Labels: <none>
Annotations: <none>
Status: Running
IP: 10.44.0.13
Init Containers:
install:
Container ID: docker://d86ec7ce801819a2073b96098055407dec5564a678c2548dd445a613314bac8e
Image: busybox
Image ID: docker-pullable://busybox@sha256:2a03a6059f21e150ae84b0973863609494aad70f0a80eaeb64bddd8d92465812
Port: <none>
Host Port: <none>
Command:
wget
-O
/work-dir/index.html
http://kubernetes.io
State: Terminated
Reason: Completed
Exit Code: 0
Started: Sun, 11 Nov 2018 13:10:03 +0000
Finished: Sun, 11 Nov 2018 13:10:03 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-x5g8c (ro)
/work-dir from workdir (rw)
Containers:
nginx:
Container ID: docker://1ec37249f98ececdfb5f80c910142c5e6edbc9373e34cd194fbd3955725da334
Image: nginx
Image ID: docker-pullable://nginx@sha256:d59a1aa7866258751a261bae525a1842c7ff0662d4f34a355d5f36826abc0341
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Sun, 11 Nov 2018 13:10:04 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/usr/share/nginx/html from workdir (rw)
/var/run/secrets/kubernetes.io/serviceaccount from default-token-x5g8c (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
workdir:
Type: EmptyDir (a temporary directory that shares a pod's lifetime)
Medium:
default-token-x5g8c:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-x5g8c
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 3m1s default-scheduler Successfully assigned default/init-demo to k8s3
Normal Pulling 3m kubelet, k8s3 pulling image "busybox"
Normal Pulled 3m kubelet, k8s3 Successfully pulled image "busybox"
Normal Created 3m kubelet, k8s3 Created container
Normal Started 3m kubelet, k8s3 Started container
Normal Pulling 2m59s kubelet, k8s3 pulling image "nginx"
Normal Pulled 2m59s kubelet, k8s3 Successfully pulled image "nginx"
Normal Created 2m59s kubelet, k8s3 Created container
Normal Started 2m59s kubelet, k8s3 Started container
$ kubectl logs init-demo -c install
Connecting to linuxtips.io (23.236.62.147:80)
Connecting to www.linuxtips.io (35.247.254.172:443)
wget: note: TLS certificate validation not implemented
saving to '/work-dir/index.html'
index.html 100% |********************************| 765k 0:00:00 ETA
'/work-dir/index.html' saved
最后，让我们从清单中删除 Pod。
$ kubectl delete -f nginx-initcontainer.yaml
pod/init-demo deleted