From b407a0103bac3bebba2a93d928aa4da9b0e828ba Mon Sep 17 00:00:00 2001 From: Jai Govindani Date: Thu, 18 Mar 2021 03:13:19 +0700 Subject: [PATCH] docs(configure-redis-using-configmap): update for clarity (#25712) * docs(configure-redis-using-configmap): update for clarity Signed-off-by: Jai Govindani * fix(configure-redis-using-configmap): incorrect volumeMount index Signed-off-by: Jai Govindani * fix(configure-redis-using-configmap): show Pod status as Running, separate commands from output Signed-off-by: Jai Govindani * fix(configure-redis-using-configmap): typo Signed-off-by: Jai Govindani * fix(configure-redis-using-configmap): configmap name Signed-off-by: Jai Govindani --- .../configure-redis-using-configmap.md | 228 ++++++++++++++---- .../pods/config/example-redis-config.yaml | 8 + 2 files changed, 189 insertions(+), 47 deletions(-) create mode 100644 content/en/examples/pods/config/example-redis-config.yaml diff --git a/content/en/docs/tutorials/configuration/configure-redis-using-configmap.md b/content/en/docs/tutorials/configuration/configure-redis-using-configmap.md index 7555a58201..b29b352aca 100644 --- a/content/en/docs/tutorials/configuration/configure-redis-using-configmap.md +++ b/content/en/docs/tutorials/configuration/configure-redis-using-configmap.md @@ -15,10 +15,8 @@ This page provides a real world example of how to configure Redis using a Config ## {{% heading "objectives" %}} -* Create a `kustomization.yaml` file containing: - * a ConfigMap generator - * a Pod resource config using the ConfigMap -* Apply the directory by running `kubectl apply -k ./` +* Create a ConfigMap with Redis configuration values +* Create a Redis Pod that mounts and uses the created ConfigMap * Verify that the configuration was correctly applied. @@ -38,82 +36,218 @@ This page provides a real world example of how to configure Redis using a Config ## Real World Example: Configuring Redis using a ConfigMap -You can follow the steps below to configure a Redis cache using data stored in a ConfigMap. +Follow the steps below to configure a Redis cache using data stored in a ConfigMap. -First create a `kustomization.yaml` containing a ConfigMap from the `redis-config` file: - -{{< codenew file="pods/config/redis-config" >}} +First create a ConfigMap with an empty configuration block: ```shell -curl -OL https://k8s.io/examples/pods/config/redis-config - -cat <./kustomization.yaml -configMapGenerator: -- name: example-redis-config - files: - - redis-config +cat <./example-redis-config.yaml +apiVersion: v1 +kind: ConfigMap +metadata: + name: example-redis-config +data: + redis-config: "" EOF ``` -Add the pod resource config to the `kustomization.yaml`: +Apply the ConfigMap created above, along with a Redis pod manifest: + +```shell +kubectl apply -f example-redis-config.yaml +kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/en/examples/pods/config/redis-pod.yaml +``` + +Examine the contents of the Redis pod manifest and note the following: + +* A volume named `config` is created by `spec.volumes[1]` +* The `key` and `path` under `spec.volumes[1].items[0]` exposes the `redis-config` key from the + `example-redis-config` ConfigMap as a file named `redis.conf` on the `config` volume. +* The `config` volume is then mounted at `/redis-master` by `spec.containers[0].volumeMounts[1]`. + +This has the net effect of exposing the data in `data.redis-config` from the `example-redis-config` +ConfigMap above as `/redis-master/redis.conf` inside the Pod. {{< codenew file="pods/config/redis-pod.yaml" >}} -```shell -curl -OL https://raw.githubusercontent.com/kubernetes/website/master/content/en/examples/pods/config/redis-pod.yaml +Examine the created objects: -cat <>./kustomization.yaml -resources: -- redis-pod.yaml -EOF +```shell +kubectl get pod/redis configmap/example-redis-config ``` -Apply the kustomization directory to create both the ConfigMap and Pod objects: +You should see the following output: ```shell -kubectl apply -k . -``` - -Examine the created objects by -```shell -> kubectl get -k . -NAME DATA AGE -configmap/example-redis-config-dgh9dg555m 1 52s - NAME READY STATUS RESTARTS AGE -pod/redis 1/1 Running 0 52s +pod/redis 1/1 Running 0 8s + +NAME DATA AGE +configmap/example-redis-config 1 14s ``` -In the example, the config volume is mounted at `/redis-master`. -It uses `path` to add the `redis-config` key to a file named `redis.conf`. -The file path for the redis config, therefore, is `/redis-master/redis.conf`. -This is where the image will look for the config file for the redis master. +Recall that we left `redis-config` key in the `example-redis-config` ConfigMap blank: -Use `kubectl exec` to enter the pod and run the `redis-cli` tool to verify that -the configuration was correctly applied: +```shell +kubectl describe configmap/example-redis-config +``` + +You should see an empty `redis-config` key: + +```shell +Name: example-redis-config +Namespace: default +Labels: +Annotations: + +Data +==== +redis-config: +``` + +Use `kubectl exec` to enter the pod and run the `redis-cli` tool to check the current configuration: ```shell kubectl exec -it redis -- redis-cli +``` + +Check `maxmemory`: + +```shell 127.0.0.1:6379> CONFIG GET maxmemory +``` + +It should show the default value of 0: + +```shell +1) "maxmemory" +2) "0" +``` + +Similarly, check `maxmemory-policy`: + +```shell +127.0.0.1:6379> CONFIG GET maxmemory-policy +``` + +Which should also yield its default value of `noeviction`: + +```shell +1) "maxmemory-policy" +2) "noeviction" +``` + +Now let's add some configuration values to the `example-redis-config` ConfigMap: + +{{< codenew file="pods/config/example-redis-config.yaml" >}} + +Apply the updated ConfigMap: + +```shell +kubectl apply -f example-redis-config.yaml +``` + +Confirm that the ConfigMap was updated: + +```shell +kubectl describe configmap/example-redis-config +``` + +You should see the configuration values we just added: + +```shell +Name: example-redis-config +Namespace: default +Labels: +Annotations: + +Data +==== +redis-config: +---- +maxmemory 2mb +maxmemory-policy allkeys-lru +``` + +Check the Redis Pod again using `redis-cli` via `kubectl exec` to see if the configuration was applied: + +```shell +kubectl exec -it redis -- redis-cli +``` + +Check `maxmemory`: + +```shell +127.0.0.1:6379> CONFIG GET maxmemory +``` + +It remains at the default value of 0: + +```shell +1) "maxmemory" +2) "0" +``` + +Similarly, `maxmemory-policy` remains at the `noeviction` default setting: + +```shell +127.0.0.1:6379> CONFIG GET maxmemory-policy +``` + +Returns: + +```shell +1) "maxmemory-policy" +2) "noeviction" +``` + +The configuration values have not changed because the Pod needs to be restarted to grab updated +values from associated ConfigMaps. Let's delete and recreate the Pod: + +```shell +kubectl delete pod redis +kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/en/examples/pods/config/redis-pod.yaml +``` + +Now re-check the configuration values one last time: + +```shell +kubectl exec -it redis -- redis-cli +``` + +Check `maxmemory`: + +```shell +127.0.0.1:6379> CONFIG GET maxmemory +``` + +It should now return the updated value of 2097152: + +```shell 1) "maxmemory" 2) "2097152" +``` + +Similarly, `maxmemory-policy` has also been updated: + +```shell 127.0.0.1:6379> CONFIG GET maxmemory-policy +``` + +It now reflects the desired value of `allkeys-lru`: + +```shell 1) "maxmemory-policy" 2) "allkeys-lru" ``` -Delete the created pod: +Clean up your work by deleting the created resources: + ```shell -kubectl delete pod redis +kubectl delete pod/redis configmap/example-redis-config ``` - - ## {{% heading "whatsnext" %}} * Learn more about [ConfigMaps](/docs/tasks/configure-pod-container/configure-pod-configmap/). - - - - diff --git a/content/en/examples/pods/config/example-redis-config.yaml b/content/en/examples/pods/config/example-redis-config.yaml new file mode 100644 index 0000000000..5b093b1213 --- /dev/null +++ b/content/en/examples/pods/config/example-redis-config.yaml @@ -0,0 +1,8 @@ +apiVersion: v1 +kind: ConfigMap +metadata: + name: example-redis-config +data: + redis-config: | + maxmemory 2mb + maxmemory-policy allkeys-lru