Editing Create and configure a basic Pod
Jump to navigation
Jump to search
Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.
The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision | Your text | ||
Line 1: | Line 1: | ||
− | + | == Create a Pod == | |
+ | * 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> | ||
+ | * To create a pod in a [[namespace]]: | ||
+ | :<code>[[kubectl create]] [[namespace]] MY_TEST_NAMESPACE</code> | ||
+ | :<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> | ||
+ | :To verify container is running: | ||
+ | ::<code>[[kubectl get]] pod NAME_POD --namespace=MY_TEST_NAMESPACE</code> | ||
+ | DevOps/Kubernetes/Certified Kubernetes Administrator/Create and configure basic Pods|Create and configure basic Pods]] | ||
+ | |||
+ | ==Set up a [[Volume]] for a [[Pod]]== | ||
+ | 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. | ||
+ | |||
+ | This feature is especially important for applications that must maintain a status, such as key-value storage engines (for example Redis) and databases. | ||
+ | |||
+ | 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: | ||
+ | |||
+ | <code>pods/storage/redis.yaml</code> | ||
+ | |||
+ | <pre>apiVersion: v1 | ||
+ | kind: Pod | ||
+ | metadata: | ||
+ | name: redis | ||
+ | spec: | ||
+ | containers: | ||
+ | - name: redis | ||
+ | image: redis | ||
+ | volumeMounts: | ||
+ | - name: redis-storage | ||
+ | mountPath: /data/redis | ||
+ | volumes: | ||
+ | - name: redis-storage | ||
+ | emptyDir: {}</pre> | ||
+ | |||
+ | |||
+ | '''1.Create the Pod''' | ||
+ | <code>kubectl apply -f https://k8s.io/examples/pods/storage/redis.yaml</code> | ||
+ | |||
+ | '''2. Verify the Pod Container is running''' | ||
+ | <code>kubectl get pod redis --watch</code> | ||
+ | |||
+ | output: | ||
+ | |||
+ | <pre>NAME READY STATUS RESTARTS AGE | ||
+ | redis 1/1 Running 0 13s</pre> | ||
+ | |||
+ | '''3.In another terminal, open an interactive session inside the Container that is running:''' | ||
+ | <code>kubectl exec -it redis -- /bin/bash</code> | ||
+ | |||
+ | '''4.In the terminal, go to <code>/data/redis</code> and create a file:''' | ||
+ | <pre>root@redis:/data# cd /data/redis/ | ||
+ | root@redis:/data/redis# echo Hello > test-file</pre> | ||
+ | |||
+ | '''5.In the terminal, list the running processes:''' | ||
+ | <pre>root@redis:/data/redis# apt-get update | ||
+ | root@redis:/data/redis# apt-get install procps | ||
+ | root@redis:/data/redis# ps aux</pre> | ||
+ | |||
+ | output: | ||
+ | <pre>USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND | ||
+ | redis 1 0.1 0.1 33308 3828 ? Ssl 00:46 0:00 redis-server *:6379 | ||
+ | root 12 0.0 0.0 20228 3020 ? Ss 00:47 0:00 /bin/bash | ||
+ | root 15 0.0 0.0 17500 2072 ? R+ 00:48 0:00 ps aux</pre> | ||
+ | |||
+ | 6.In the terminal, kill the Redis process: | ||
+ | |||
+ | root@redis:/data/redis# kill <pid> | ||
+ | |||
+ | where <pid>is the process ID (PID) of Redis. | ||
+ | |||
+ | 7.In the original terminal, observe the changes in the Redis Pod. You will eventually see something like the following: | ||
+ | |||
+ | NAME READY STATUS RESTARTS AGE | ||
+ | redis 1/1 Running 0 13s | ||
+ | redis 0/1 Completed 0 6m | ||
+ | redis 1/1 Running 1 6m | ||
+ | |||
+ | At this point, the Container has been destroyed and restarted. This is because the Redis Pod has a restartPolicy (restart policy) of Always(always). | ||
+ | |||
+ | 1.Open a terminal in the restarted Container: | ||
+ | |||
+ | <code>[[kubectl exec]] -it redis -- /bin/bash</code> | ||
+ | |||
+ | 2.In the terminal, go to /data/redisand verify that it test-filestill exists: | ||
+ | |||
+ | root@redis:/data/redis# cd /data/redis/ | ||
+ | root@redis:/data/redis# ls | ||
+ | test-file | ||
+ | |||
+ | 3.Remove the Pod you created for this exercise: | ||
+ | * <code>kubectl delete pod redis</code> | ||
+ | |||
+ | == See also == | ||
+ | * {{K8s}} | ||
+ | |||
+ | [[Category:Kubernetes]] | ||
+ | |||
+ | {{CC license}} | ||
+ | Source: wikiversity |
Advertising: