Write new task: Defining Environment Variables for a Container.

_data/tasks.yml

@@ -2,6 +2,10 @@ bigheader: "Tasks"
 toc:
 - title: Tasks
   path: /docs/tasks/
+- title: Configuring Pods and Containers
+  section:
+  - title: Defining Environment Variables for a Container
+    path: /docs/tasks/configure-pod-container/define-environment-variable-container/
 - title: Accessing Applications in a Cluster
   section:
   - title: Using Port Forwarding to Access Applications in a Cluster

_includes/task-tutorial-prereqs.md

@@ -0,0 +1,4 @@
+You need to have a Kubernetes cluster, and the kubectl command-line tool must
+be configured to communicate with your cluster. If you do not already have a
+cluster, you can create one by using
+[Minikube](/docs/getting-started-guides/minikube).

docs/tasks/configure-pod-container/define-environment-variable-container.md

@@ -0,0 +1,77 @@
+---
+---
+
+{% capture overview %}
+
+This page shows how to define environment variables when you run a container
+in a Kubernetes Pod.
+
+{% endcapture %}
+
+
+{% capture prerequisites %}
+
+{% include task-tutorial-prereqs.md %}
+
+{% endcapture %}
+
+
+{% capture steps %}
+
+### Defining an environment variable for a container
+
+When you create a Pod, you can set environment variables for the containers
+that run in the Pod. To set environment variables, include the `env` field in
+the configuration file.
+
+In this exercise, you create a Pod that runs one container. The configuration
+file for the Pod defines an environment variable with name `DEMO_GREETING` and
+value `"Hello from the environment"`. Here is the configuration file for the
+Pod:
+
+{% include code.html language="yaml" file="envars.yaml" ghlink="/docs/tasks/configure-pod-container/envars.yaml" %}
+
+1. Create a Pod based on the YAML configuration file:
+
+        export REPO=https://raw.githubusercontent.com/kubernetes/kubernetes.github.io/master
+        kubectl create -f $REPO/docs/tasks/configure-pod-container/envars.yaml
+
+1. List the running Pods:
+
+        kubectl get pods
+
+    The output is similar to this:
+
+        NAME            READY     STATUS    RESTARTS   AGE
+        envar-demo      1/1       Running   0          9s
+
+1. Get a shell to the container running in your Pod:
+
+        kubectl exec -it envar-demo -- /bin/bash
+
+1. In your shell, run the `printenv` command to list the environment variables.
+
+        root@envar-demo:/# printenv
+
+    The output is similar to this:
+
+        NODE_VERSION=4.4.2
+        EXAMPLE_SERVICE_PORT_8080_TCP_ADDR=10.3.245.237
+        HOSTNAME=envar-demo
+        ...
+        DEMO_GREETING=Hello from the environment
+
+1. To exit the shell, enter `exit`.
+
+{% endcapture %}
+
+{% capture whatsnext %}
+
+* Learn more about [environment variables](/docs/user-guide/environment-guide/).
+* Learn about [using secrets as environment variables](/docs/user-guide/secrets/#using-secrets-as-environment-variables).
+* See [EnvVarSource](/docs/api-reference/v1/definitions/#_v1_envvarsource).
+
+{% endcapture %}
+
+
+{% include templates/task.md %}

docs/tasks/configure-pod-container/envars.yaml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: envar-demo
+  labels:
+    purpose: demonstrate-envars
+spec:
+  containers:
+  - name: envar-demo-container
+    image: gcr.io/google-samples/node-hello:1.0
+    env:
+    - name: DEMO_GREETING
+      value: "Hello from the environment"