Write new task: Configuring Pod Initialization.

2017-01-03 10:14:46 -08:00
parent 0d9e5069b2
commit 205a3007a8
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: {}
+