mirror of https://github.com/k3s-io/k3s
110 lines
3.1 KiB
Markdown
110 lines
3.1 KiB
Markdown
<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->
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<!-- BEGIN STRIP_FOR_RELEASE -->
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
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If you are using a released version of Kubernetes, you should
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refer to the docs that go with that version.
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<strong>
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The latest 1.0.x release of this document can be found
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[here](http://releases.k8s.io/release-1.0/docs/user-guide/getting-into-containers.md).
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Documentation for other releases can be found at
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[releases.k8s.io](http://releases.k8s.io).
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</strong>
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--
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<!-- END STRIP_FOR_RELEASE -->
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<!-- END MUNGE: UNVERSIONED_WARNING -->
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# Getting into containers: kubectl exec
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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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## Using kubectl exec to check the environment variables of a container
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Kubernetes exposes [services](services.md#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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```console
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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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```console
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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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```console
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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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```console
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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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```console
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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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```console
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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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```console
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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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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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