Move Guide toic to Tasks: kubectl exec.
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- title: Using the Kubectl Command-Line
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section:
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- docs/tasks/kubectl/list-all-running-container-images.md
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- docs/tasks/kubectl/get-shell-running-container.md
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- title: Configuring Pods and Containers
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section:
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@ -0,0 +1,148 @@
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---
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assignees:
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- caesarxuchao
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- mikedanese
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title: Getting a Shell to a Running Container
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---
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{% capture overview %}
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This page shows how to use `kubectl exec` to get a shell to a
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running Container.
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{% endcapture %}
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{% capture prerequisites %}
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{% include task-tutorial-prereqs.md %}
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{% endcapture %}
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{% capture steps %}
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## Getting a shell to a Container
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In this exercise, you create a Pod that has one Container. The Container
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runs the nginx image. Here is the configuration file for the Pod:
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{% include code.html language="yaml" file="shell-demo.yaml" ghlink="/docs/tasks/kubectl/shell-demo.yaml" %}
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Create the Pod:
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```shell
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kubectl create -f https://k8s.io/docs/tasks/kubectl/shell-demo.yaml
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```
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Verify that the Container is running:
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```shell
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kubectl get pod shell-demo
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```
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Get a shell to the running Container:
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```shell
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kubectl exec -it shell-demo -- /bin/bash
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```
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In your shell, list the running processes:
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```shell
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root@shell-demo:/# ps aux
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```
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In your shell, list the nginx processes:
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```shell
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root@shell-demo:/# ps aux | grep nginx
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```
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In your shell, experiment with other commands. Here are
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some examples:
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```shell
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root@shell-demo:/# ls /
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root@shell-demo:/# cat /proc/mounts
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root@shell-demo:/# cat /proc/1/maps
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root@shell-demo:/# apt-get update
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root@shell-demo:/# apt-get install tcpdump
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root@shell-demo:/# tcpdump
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root@shell-demo:/# apt-get install lsof
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root@shell-demo:/# lsof
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```
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## Writing the root page for nginx
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Look again at the configuration file for your Pod. The Pod
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has an `emptyDir` volume, and the Container mounts the volume
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at `/usr/share/nginx/html`.
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In your shell, create an `index.html` file in the `/usr/share/nginx/html`
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directory:
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```shell
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root@shell-demo:/# echo Hello shell demo > /usr/share/nginx/html/index.html
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```
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In your shell, send a GET request to the nginx server:
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```shell
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root@shell-demo:/# apt-get update
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root@shell-demo:/# apt-get install curl
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root@shell-demo:/# curl localhost
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```
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The output shows the text that you wrote to the `index.html` file:
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```shell
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Hello shell demo
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```
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When you are finished with your shell, enter `exit`.
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## Running individual commands in a Container
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In an ordinary command window, not your shell, list the environment
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variables in the running Container:
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```shell
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kubectl exec shell-demo env
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```
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Experiment running other commands. Here are some examples:
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```shell
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kubectl exec shell-demo ps aux
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kubectl exec shell-demo ls /
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kubectl exec shell-demo cat /proc/1/mounts
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```
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{% endcapture %}
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{% capture discussion %}
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## Opening a shell when a Pod has more than one Container
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If a Pod has more than one Container, use `--container` or `-c` to
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specify a Container in the `kubectl exec` command. For example,
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suppose you have a Pod named my-pod, and the Pod has two containers
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named main-app and helper-app. The following command would open a
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shell to the main-app Container.
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```shell
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kubectl exec -it my-pod --container main-app -- /bin/bash
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```
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{% endcapture %}
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{% capture whatsnext %}
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* [kubectl exec](/docs/user-guide/kubectl/v1.5/#exec)
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{% endcapture %}
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{% include templates/task.md %}
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@ -0,0 +1,14 @@
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apiVersion: v1
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kind: Pod
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metadata:
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name: shell-demo
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spec:
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volumes:
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- name: shared-data
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emptyDir: {}
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containers:
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- name: nginx
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image: nginx
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volumeMounts:
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- name: shared-data
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mountPath: /usr/share/nginx/html
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@ -5,70 +5,6 @@ assignees:
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title: Running Commands in a Container with kubectl exec
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---
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Developers can use `kubectl exec` to run commands in a container. This guide demonstrates two use cases.
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{% include user-guide-content-moved.md %}
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## Using kubectl exec to check the environment variables of a container
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Kubernetes exposes [services](/docs/user-guide/services/#environment-variables) through environment variables. It is convenient to check these environment variables using `kubectl exec`.
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We first create a pod and a service,
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```shell
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$ kubectl create -f examples/guestbook/redis-master-controller.yaml
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$ kubectl create -f examples/guestbook/redis-master-service.yaml
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```
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wait until the pod is Running and Ready,
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```shell
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$ kubectl get pod
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NAME READY REASON RESTARTS AGE
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redis-master-ft9ex 1/1 Running 0 12s
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```
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then we can check the environment variables of the pod,
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```shell
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$ kubectl exec redis-master-ft9ex env
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...
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REDIS_MASTER_SERVICE_PORT=6379
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REDIS_MASTER_SERVICE_HOST=10.0.0.219
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...
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```
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We can use these environment variables in applications to find the service.
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## Using kubectl exec to check the mounted volumes
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It is convenient to use `kubectl exec` to check if the volumes are mounted as expected.
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We first create a Pod with a volume mounted at /data/redis,
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```shell
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kubectl create -f docs/user-guide/walkthrough/pod-redis.yaml
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```
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wait until the pod is Running and Ready,
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```shell
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$ kubectl get pods
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NAME READY REASON RESTARTS AGE
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storage 1/1 Running 0 1m
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```
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we then use `kubectl exec` to verify that the volume is mounted at /data/redis,
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```shell
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$ kubectl exec storage ls /data
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redis
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```
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## Using kubectl exec to open a bash terminal in a pod
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After all, open a terminal in a pod is the most direct way to introspect the pod. Assuming the pod/storage is still running, run
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```shell
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$ kubectl exec -ti storage -- bash
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root@storage:/data#
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```
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This gets you a terminal.
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[Getting a Shell to a Running Container](/docs/tasks/kubectl/get-shell-running-container/)
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