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| − | == Create a Pod ==
| + | #redirect [[Create an configure basic Pods]] |
| − | * To create a [[Pod]] based on a <code>[[yaml]]</code> definition file: <code>[[kubectl apply]] -f https://k8s.io/examples/pods/storage/redis.yaml</code><ref>https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/</ref>
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| − | * To create a pod in a [[namespace]]:
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| − | :<code>[[kubectl create]] [[namespace]] MY_TEST_NAMESPACE</code>
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| − | :<code>[[kubectl]] apply -f https://k8s.io/examples/pods/storage/redis.yaml --namespace=MY_TEST_NAMESPACE</code><ref>https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/</ref>
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| − | * To verify container is running:
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| − | :<code>[[kubectl get pod]] NAME_POD --namespace=MY_TEST_NAMESPACE</code>
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| − | ==Set up a [[Volume]] for a [[Pod]]==
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| − | The file system of a [[DevOps/Container|Container]] exists as long as the Container exists. Therefore, when a Container is destroyed or restarted, changes made to the file system are lost. For more consistent storage that is independent of the Container life cycle, you can use a Volume, review different Volume types in https://kubernetes.io/docs/concepts/storage/volumes/#types-of-volumes.
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| − | This feature is especially important for applications that must maintain a status, such as key-value storage engines (for example Redis) and databases.
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| − | Create a Pod that runs a single Container. This Pod has a Volume of type <code>emptyDir</code> (empty directory) (see [[DevOps/Kubernetes/Volumes|Volume]] for volume types) that exists throughout the Pod's life cycle, even when the Container is destroyed and restarted. Here is the Pod configuration file:
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| − | <code>pods/storage/redis.yaml</code>
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| − | apiVersion: v1
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| − | [[kind: Pod]]
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| − | metadata:
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| − | name: redis
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| − | spec:
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| − | containers:
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| − | - name: redis
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| − | image: redis
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| − | [[volumeMounts]]:
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| − | - name: redis-storage
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| − | mountPath: /data/redis
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| − | volumes:
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| − | - name: redis-storage
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| − | emptyDir: {}</pre>
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| − | '''1.Create the Pod'''
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| − | <code>kubectl apply -f https://k8s.io/examples/pods/storage/redis.yaml</code>
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| − | pod/redis created
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| − | '''2. Verify the Pod Container is running'''
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| − | <code>kubectl get pod redis --watch</code>
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| − | <pre>NAME READY STATUS RESTARTS AGE
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| − | redis 1/1 Running 0 13s</pre>
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| − | '''3.In another terminal, open an interactive session inside the Container that is running:'''
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| − | <code>kubectl exec -it redis -- /bin/bash</code>
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| − | '''4.In the terminal, go to <code>/data/redis</code> and create a file:'''
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| − | <pre>root@redis:/data# cd /data/redis/
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| − | root@redis:/data/redis# echo Hello > test-file</pre>
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| − | '''5.In the terminal, list the running processes:'''
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| − | <pre>root@redis:/data/redis# apt-get update
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| − | root@redis:/data/redis# apt-get install procps
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| − | root@redis:/data/redis# ps aux</pre>
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| − | output:
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| − | <pre>USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
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| − | redis 1 0.1 0.1 33308 3828 ? Ssl 00:46 0:00 redis-server *:6379
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| − | root 12 0.0 0.0 20228 3020 ? Ss 00:47 0:00 /bin/bash
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| − | root 15 0.0 0.0 17500 2072 ? R+ 00:48 0:00 ps aux</pre>
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| − | 6.In the terminal, kill the Redis process:
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| − | root@redis:/data/redis# kill <pid>
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| − | where <pid>is the process ID (PID) of Redis.
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| − | 7.In the original terminal, observe the changes in the Redis Pod. You will eventually see something like the following:
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| − | NAME READY STATUS RESTARTS AGE
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| − | redis 1/1 Running 0 13s
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| − | redis 0/1 Completed 0 6m
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| − | redis 1/1 Running 1 6m
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| − | At this point, the Container has been destroyed and restarted. This is because the Redis Pod has a restartPolicy (restart policy) of Always(always).
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| − | 1.Open a terminal in the restarted Container:
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| − | <code>[[kubectl exec]] -it redis -- /bin/bash</code>
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| − | 2.In the terminal, go to /data/redisand verify that it test-filestill exists:
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| − | root@redis:/data/redis# cd /data/redis/
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| − | root@redis:/data/redis# ls
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| − | test-file
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| − | 3.Remove the Pod you created for this exercise:
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| − | * <code>[[kubectl delete]] pod redis</code>
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| − | == See also ==
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| − | * {{Pod}}
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| − | * {{CKA}}
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| − | * {{K8s}}
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| − | [[Category:Kubernetes]]
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| − | {{CC license}}
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| − | Source: wikiversity
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