John Mulhausen
108 lines
2.7 KiB
Markdown
108 lines
2.7 KiB
Markdown
---
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layout: docwithnav
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title: "Getting into containers: kubectl exec"
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---
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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.html#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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{% highlight console %}
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{% raw %}
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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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{% endraw %}
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{% endhighlight %}
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wait until the pod is Running and Ready,
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{% highlight console %}
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{% raw %}
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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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{% endraw %}
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{% endhighlight %}
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then we can check the environment variables of the pod,
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{% highlight console %}
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{% raw %}
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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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{% endraw %}
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{% endhighlight %}
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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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{% highlight console %}
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{% raw %}
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kubectl create -f docs/user-guide/walkthrough/pod-redis.yaml
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{% endraw %}
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{% endhighlight %}
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wait until the pod is Running and Ready,
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{% highlight console %}
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{% raw %}
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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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{% endraw %}
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{% endhighlight %}
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we then use `kubectl exec` to verify that the volume is mounted at /data/redis,
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{% highlight console %}
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{% raw %}
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$ kubectl exec storage ls /data
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redis
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{% endraw %}
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{% endhighlight %}
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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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{% highlight console %}
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{% raw %}
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$ kubectl exec -ti storage -- bash
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root@storage:/data#
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{% endraw %}
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{% endhighlight %}
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This gets you a terminal.
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[]()
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