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Rewrite Configuring Redis using a ConfigMap #48716

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Rewrite Configuring Redis using a ConfigMap
jerry-li-dev Nov 14, 2024
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Update configure-redis-using-configmap.md
jerry-li-dev Nov 14, 2024
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Update configure-redis-using-configmap.md
jerry-li-dev Nov 14, 2024
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Merge branch 'rewrite-config-redis-with-configmap' of https://github.…
jerry-li-dev Nov 14, 2024
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90 changes: 47 additions & 43 deletions content/en/docs/tutorials/configuration/configure-redis-using-configmap.md
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Expand Up @@ -9,37 +9,37 @@ weight: 30

<!-- overview -->

This page provides a real world example of how to configure Redis using a ConfigMap and builds upon the [Configure a Pod to Use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/) task.
After you [configure a Pod to use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/), you can then use a ConfigMap to configure Redis.

## What you'll learn
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Is there a reason for moving away from the conventional Objectives section heading?



## {{% heading "objectives" %}}

In this tutorial, you'll learn how to do the following tasks:

* 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.

## Requirements
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Here too, why move away from the standardized prerequisites block?


- Kubernetes cluster
- kubectl command-line tool (`kubectl` 1.14 and above) configured to communicate with your cluster.
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I think this statement is misleading. It implies you could use kubectl 1.14, but that is not correct for most users today. A specific version reference could probably be dropped here since 1.14 (and many more of the later ones) are well end of life by this point.


## {{% heading "prerequisites" %}}


{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}

* The example shown on this page works with `kubectl` 1.14 and above.
* Understand [Configure a Pod to Use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/).
Run the following command to check the kubectl version:

```shell
kubectl version
```
> **_NOTE:_** It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts.

{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}

<!-- lessoncontent -->

## 1. Create a Redis ConfigMap
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I don't think we want to use bullet number is section headers.


## Real World Example: Configuring Redis using a ConfigMap

Follow the steps below to configure a Redis cache using data stored in a ConfigMap.
You could use data stored in a ConfigMap to configure a Redis cache.

First create a ConfigMap with an empty configuration block:
1. Run the following command to create a ConfigMap with an empty configuration block:

```shell
cat <<EOF >./example-redis-config.yaml
Expand All @@ -52,17 +52,17 @@ data:
EOF
```

Apply the ConfigMap created above, along with a Redis pod manifest:
2. Run the following commands to 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/main/content/en/examples/pods/config/redis-pod.yaml
```

Examine the contents of the Redis pod manifest and note the following:
3. 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].configMap.items[0]` exposes the `redis-config` key from the
* The `key` and `path` under `spec.volumes[1].configMap.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]`.

Expand All @@ -71,10 +71,10 @@ ConfigMap above as `/redis-master/redis.conf` inside the Pod.

{{% code_sample file="pods/config/redis-pod.yaml" %}}

Examine the created objects:
4. To confirm the objects were created correctly, run the following command:

```shell
kubectl get pod/redis configmap/example-redis-config
kubectl get pod/redis configmap/example-redis-config
```

You should see the following output:
Expand All @@ -87,7 +87,7 @@ NAME DATA AGE
configmap/example-redis-config 1 14s
```

Recall that we left `redis-config` key in the `example-redis-config` ConfigMap blank:
5. Run the following command to print the `example-redis-config` ConfigMap, to confirm that the `redis-config` key is empty:

```shell
kubectl describe configmap/example-redis-config
Expand All @@ -106,49 +106,51 @@ Data
redis-config:
```

Use `kubectl exec` to enter the pod and run the `redis-cli` tool to check the current configuration:
6. Run the following command, `kubectl exec` to enter the pod. Use the following option, `redis-cli` to check the current configuration:

```shell
kubectl exec -it redis -- redis-cli
```

Check `maxmemory`:
7. Run the following command to confirm the value of the `maxmemory` key:

```shell
127.0.0.1:6379> CONFIG GET maxmemory
```

It should show the default value of 0:
The `maxmemory` key should have the default value of 0:

```shell
1) "maxmemory"
2) "0"
```

Similarly, check `maxmemory-policy`:
8. Run the following command to confirm the value of the `maxmemory-policy` key:

```shell
127.0.0.1:6379> CONFIG GET maxmemory-policy
```

Which should also yield its default value of `noeviction`:
The `maxmemory-policy` key should have the default value of `noeviction`:

```shell
1) "maxmemory-policy"
2) "noeviction"
```

Now let's add some configuration values to the `example-redis-config` ConfigMap:
## 2. Configure a Redis ConfigMap

After you create a blank Redis ConfigMap, you can use the following command to add configuration values to the `example-redis-config` ConfigMap:

{{% code_sample file="pods/config/example-redis-config.yaml" %}}

Apply the updated ConfigMap:
1. Run the following command to apply the updated ConfigMap:

```shell
kubectl apply -f example-redis-config.yaml
```

Confirm that the ConfigMap was updated:
2. To confirm that the ConfigMap was updated, run the following command:

```shell
kubectl describe configmap/example-redis-config
Expand All @@ -170,79 +172,81 @@ maxmemory 2mb
maxmemory-policy allkeys-lru
```

Check the Redis Pod again using `redis-cli` via `kubectl exec` to see if the configuration was applied:
3. To confirm the configuration was applied, check the Redis Pod values. Run the following command, `kubectl exec` with the `redis-cli` key.

```shell
kubectl exec -it redis -- redis-cli
```

Check `maxmemory`:
4. Run the following command to confirm the value of the `maxmemory` key:

```shell
127.0.0.1:6379> CONFIG GET maxmemory
```

It remains at the default value of 0:
The `maxmemory` key should remain at the default value of 0:

```shell
1) "maxmemory"
2) "0"
```

Similarly, `maxmemory-policy` remains at the `noeviction` default setting:
5. Run the following command to confirm the value of the `maxmemory-policy` key remains at the default value of `noeviction`:

```shell
127.0.0.1:6379> CONFIG GET maxmemory-policy
```

Returns:
The `maxmemory-policy` key should remain at the default value of `noeviction`:

```shell
1) "maxmemory-policy"
2) "noeviction"
```
The configuration values do not grab updated values from the associated ConfigMaps until you restart the Pod.

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:
6. Run the following command to delete and recreate the Pod:

```shell
kubectl delete pod redis
kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/main/content/en/examples/pods/config/redis-pod.yaml
```

Now re-check the configuration values one last time:
7. Run the following command to recheck the configuration values:

```shell
kubectl exec -it redis -- redis-cli
```

Check `maxmemory`:
7. Run the following command to confirm the value of the `maxmemory` key:

```shell
127.0.0.1:6379> CONFIG GET maxmemory
```

It should now return the updated value of 2097152:
The `maxmemory` key should have a value of `2097152`:

```shell
1) "maxmemory"
2) "2097152"
```

Similarly, `maxmemory-policy` has also been updated:
8. Run the following command to confirm the value of the `maxmemory-policy` key:

```shell
127.0.0.1:6379> CONFIG GET maxmemory-policy
```

It now reflects the desired value of `allkeys-lru`:
The `maxmemory-policy`should have the value of `allkeys-lru`:

```shell
1) "maxmemory-policy"
2) "allkeys-lru"
```

Clean up your work by deleting the created resources:
## 3. Clean up resources

After you complete this tutorial, you can run the following command delete all resources you've created:

```shell
kubectl delete pod/redis configmap/example-redis-config
Expand All @@ -252,4 +256,4 @@ kubectl delete pod/redis configmap/example-redis-config


* Learn more about [ConfigMaps](/docs/tasks/configure-pod-container/configure-pod-configmap/).
* Follow an example of [Updating configuration via a ConfigMap](/docs/tutorials/configuration/updating-configuration-via-a-configmap/).
* Learn how to [update configurations via ConfigMaps](/docs/tutorials/configuration/updating-configuration-via-a-configmap/).
11 changes: 4 additions & 7 deletions content/en/includes/task-tutorial-prereqs.md
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@@ -1,8 +1,5 @@
You need to have a Kubernetes cluster, and the kubectl command-line tool must
be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a
cluster, you can create one by using
[minikube](https://minikube.sigs.k8s.io/docs/tutorials/multi_node/)
or you can use one of these Kubernetes playgrounds:
- If you do not already have a cluster, you can create one by using [minikube](https://minikube.sigs.k8s.io/docs/tutorials/multi_node/) or you can use one of these Kubernetes playgrounds:
- [Killercoda](https://killercoda.com/playgrounds/scenario/kubernetes)
- [Play with Kubernetes](https://labs.play-with-k8s.com/)

* [Killercoda](https://killercoda.com/playgrounds/scenario/kubernetes)
* [Play with Kubernetes](https://labs.play-with-k8s.com/)
* Understand how to [configure a Pod to use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/).
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I suggest you to preserve the task-tutorial-prereqs.md as-is, not modifying in this PR.

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@jerry-li-dev jerry-li-dev Nov 18, 2024 •
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The formatting in the current task tutorial file is not usable. It has to be changed.

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Hi Jerry, you should clarify how it's not usable in your PR description and why the change is important.

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Existing formatting seems fine to me, so an explanation of why you find it not usable would be helpful.