Merge pull request #2157 from steveperry-53/init-containers

Write new task: Configuring Pod Initialization.
2017-01-09 13:16:32 -08:00
parent 0d9e5069b2 205a3007a8
commit a9f02c283d
3 changed files with 124 additions and 0 deletions
@@ -13,6 +13,7 @@ toc:
  - docs/tasks/configure-pod-container/pull-image-private-registry.md
  - docs/tasks/configure-pod-container/configure-liveness-readiness-probes.md
  - docs/tasks/configure-pod-container/communicate-containers-same-pod.md
  - docs/tasks/configure-pod-container/configure-pod-initialization.md 
 - title: Accessing Applications in a Cluster
  section:
@@ -0,0 +1,91 @@
 ---
 title: Configuring Pod Initialization
 ---
 {% capture overview %}
 This page shows how to use an init Container to initialize a Pod before the
 application Container runs.
 {% endcapture %}
 {% capture prerequisites %}
 {% include task-tutorial-prereqs.md %}
 {% endcapture %}
 {% capture steps %}
 ### Creating a Pod that has an init Container
 In this exercise you create a Pod that has one application Container and one
 init Container. The init Container runs to completion before the application
 container starts.
 Here is the configuration file for the Pod:
 {% include code.html language="yaml" file="init-containers.yaml" ghlink="/docs/tasks/configure-pod-container/init-containers.yaml" %}
 In the configuration file, you can see that the Pod has a Volume that the init
 Container and the application Container share. Notice that the init Container
 is a beta feature and is specified as an annotation.
 The init Container mounts the
 shared Volume at `/work-dir`, and the application Container mounts the shared
 Volume at `/usr/share/nginx/html`. The init Container runs the following command
 and then terminates:
     wget -O /work-dir/index.html http://kubernetes.io
 Notice that the init Container writes the `index.html` file in the root directory
 of the nginx server.
 Create the Pod:
    kubectl create -f http://k8s.io/docs/tasks/configure-pod-container/init-containers.yaml
 Verify that the nginx Container is running:
    kubectl get pod init-demo
 The output shows that the nginx Container is running:
    NAME      READY     STATUS    RESTARTS   AGE
    nginx     1/1       Running   0          43m
 Get a shell into nginx the Container running in the init-demo Pod:
    kubectl exec -it init-demo -- /bin/bash
 In your shell, send a GET request to the nginx server:
    root@nginx:~# apt-get update
    root@nginx:~# apt-get install curl
    root@nginx:~# curl localhost
 The output shows that nginx is serving the web page that was written by the init container:
    <!Doctype html>
    <html id="home">
    <head>
    ...
    "url": "http://kubernetes.io/"}</script>
    </head>
    <body>
      ...
      <p>Kubernetes is open source giving you the freedom to take advantage ...</p>
      ...
 {% endcapture %}
 {% capture whatsnext %}
 * Learn more about
 [communicating between Containers running in the same Pod](/docs/tasks/configure-pod-container/communicate-containers-same-pod/).
 * Learn more about [init Containers](/docs/user-guide/pods/init-container/).
 * Learn more about [Volumes](/docs/user-guide/volumes/).
 {% endcapture %}
 {% include templates/task.md %}
@@ -0,0 +1,32 @@
 apiVersion: v1
 kind: Pod
 metadata:
  name: init-demo
  annotations:
    pod.beta.kubernetes.io/init-containers: '[
        {
            "name": "install",
            "image": "busybox",
            "command": ["wget", "-O", "/work-dir/index.html", "http://kubernetes.io"],
            "volumeMounts": [
                {
                    "name": "workdir",
                    "mountPath": "/work-dir"
                }
            ]
        }
    ]'
 spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80
    volumeMounts:
    - name: workdir
      mountPath: /usr/share/nginx/html
  dnsPolicy: Default
  volumes:
  - name: workdir
    emptyDir: {}