feat(configMap): add a warning message for ConfigMap with a specific path (#14896)

content/en/docs/tasks/configure-pod-container/configure-pod-configmap.md

@@ -22,7 +22,7 @@ ConfigMaps allow you to decouple configuration artifacts from image content to k
 
 
 ## Create a ConfigMap
-You can use either `kubectl create configmap` or a ConfigMap generator in `kustomization.yaml` to create a ConfigMap. Note that `kubectl` starts to support `kustomization.yaml` since 1.14. 
+You can use either `kubectl create configmap` or a ConfigMap generator in `kustomization.yaml` to create a ConfigMap. Note that `kubectl` starts to support `kustomization.yaml` since 1.14.
 
 ### Create a ConfigMap Using kubectl create configmap
 
@@ -444,21 +444,21 @@ configmap/special-config-2-c92b5mmcf2 created
    {{< codenew file="pods/pod-single-configmap-env-variable.yaml" >}}
 
    Create the Pod:
- 
+
  ```shell
  kubectl create -f https://kubernetes.io/examples/pods/pod-single-configmap-env-variable.yaml
  ```
-   
+
-   Now, the Pod's output includes environment variable `SPECIAL_LEVEL_KEY=very`. 
+   Now, the Pod's output includes environment variable `SPECIAL_LEVEL_KEY=very`.
- 
+
 ### Define container environment variables with data from multiple ConfigMaps
- 
+
  * As with the previous example, create the ConfigMaps first.
 
    {{< codenew file="configmap/configmaps.yaml" >}}
 
    Create the ConfigMap:
- 
+
  ```shell
  kubectl create -f https://kubernetes.io/examples/configmap/configmaps.yaml
  ```
@@ -468,43 +468,43 @@ configmap/special-config-2-c92b5mmcf2 created
   {{< codenew file="pods/pod-multiple-configmap-env-variable.yaml" >}}
 
   Create the Pod:
- 
+
  ```shell
  kubectl create -f https://kubernetes.io/examples/pods/pod-multiple-configmap-env-variable.yaml
  ```
 
-  Now, the Pod's output includes environment variables `SPECIAL_LEVEL_KEY=very` and `LOG_LEVEL=INFO`. 
+  Now, the Pod's output includes environment variables `SPECIAL_LEVEL_KEY=very` and `LOG_LEVEL=INFO`.
 
-## Configure all key-value pairs in a ConfigMap as container environment variables 
+## Configure all key-value pairs in a ConfigMap as container environment variables
 
 {{< note >}}
 This functionality is available in Kubernetes v1.6 and later.
 {{< /note >}}
 
-* Create a ConfigMap containing multiple key-value pairs. 
+* Create a ConfigMap containing multiple key-value pairs.
 
   {{< codenew file="configmap/configmap-multikeys.yaml" >}}
 
   Create the ConfigMap:
- 
+
  ```shell
  kubectl create -f https://kubernetes.io/examples/configmap/configmap-multikeys.yaml
  ```
 
 * Use `envFrom` to define all of the ConfigMap's data as container environment variables. The key from the ConfigMap becomes the environment variable name in the Pod.
-   
+
  {{< codenew file="pods/pod-configmap-envFrom.yaml" >}}
 
  Create the Pod:
- 
+
  ```shell
  kubectl create -f https://kubernetes.io/examples/pods/pod-configmap-envFrom.yaml
  ```
 
- Now, the Pod's output includes environment variables `SPECIAL_LEVEL=very` and `SPECIAL_TYPE=charm`. 
+ Now, the Pod's output includes environment variables `SPECIAL_LEVEL=very` and `SPECIAL_TYPE=charm`.
 
 
-## Use ConfigMap-defined environment variables in Pod commands  
+## Use ConfigMap-defined environment variables in Pod commands
 
 You can use ConfigMap-defined environment variables in the `command` section of the Pod specification using the `$(VAR_NAME)` Kubernetes substitution syntax.
 
@@ -524,23 +524,23 @@ produces the following output in the `test-container` container:
 very charm
 ```
 
-## Add ConfigMap data to a Volume 
+## Add ConfigMap data to a Volume
 
-As explained in [Create ConfigMaps from files](#create-configmaps-from-files), when you create a ConfigMap using ``--from-file``, the filename becomes a key stored in the `data` section of the ConfigMap. The file contents become the key's value. 
+As explained in [Create ConfigMaps from files](#create-configmaps-from-files), when you create a ConfigMap using ``--from-file``, the filename becomes a key stored in the `data` section of the ConfigMap. The file contents become the key's value.
 
 The examples in this section refer to a ConfigMap named special-config, shown below.
 
 {{< codenew file="configmap/configmap-multikeys.yaml" >}}
 
 Create the ConfigMap:
- 
+
 ```shell
 kubectl create -f https://kubernetes.io/examples/configmap/configmap-multikeys.yaml
 ```
 
 ### Populate a Volume with data stored in a ConfigMap
 
-Add the ConfigMap name under the `volumes` section of the Pod specification. 
+Add the ConfigMap name under the `volumes` section of the Pod specification.
 This adds the ConfigMap data to the directory specified as `volumeMounts.mountPath` (in this case, `/etc/config`).
 The `command` section references the `special.level` item stored in the ConfigMap.
 
@@ -565,7 +565,7 @@ If there are some files in the `/etc/config/` directory, they will be deleted.
 
 ### Add ConfigMap data to a specific path in the Volume
 
-Use the `path` field to specify the desired file path for specific ConfigMap items. 
+Use the `path` field to specify the desired file path for specific ConfigMap items.
 In this case, the `SPECIAL_LEVEL` item will be mounted in the `config-volume` volume at `/etc/config/keys`.
 
 {{< codenew file="pods/pod-configmap-volume-specific-key.yaml" >}}
@@ -582,6 +582,10 @@ When the pod runs, the command `cat /etc/config/keys` produces the output below:
 very
 ```
 
+{{< caution >}}
+Like before, all previous files in the `/etc/config/` directory will be deleted.
+{{< /caution >}}
+
 ### Project keys to specific paths and file permissions
 
 You can project keys to specific paths and specific permissions on a per-file
@@ -636,9 +640,9 @@ data:
    ```shell
    kubectl get events
    ```
-   
+
    The output is similar to this:
-   ```   
+   ```
    LASTSEEN FIRSTSEEN COUNT NAME          KIND  SUBOBJECT  TYPE      REASON                            SOURCE                MESSAGE
    0s       0s        1     dapi-test-pod Pod              Warning   InvalidEnvironmentVariableNames   {kubelet, 127.0.0.1}  Keys [1badkey, 2alsobad] from the EnvFrom configMap default/myconfig were skipped since they are considered invalid environment variable names.
    ```
@@ -646,11 +650,11 @@ data:
 - ConfigMaps reside in a specific [namespace](/docs/concepts/overview/working-with-objects/namespaces/). A ConfigMap can only be referenced by pods residing in the same namespace.
 
 - Kubelet doesn't support the use of ConfigMaps for pods not found on the API server. This includes pods created via the Kubelet's `--manifest-url` flag, `--config` flag, or the Kubelet REST API.
-   
+
    {{< note >}}
    These are not commonly-used ways to create pods.
    {{< /note >}}
-   
+
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