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

---
title: Configure a Pod to Use a ConfigMap
content_type: task
weight: 190
card:
  name: tasks
  weight: 50
---

<!-- overview -->
Many applications rely on configuration which is used during either application initialization or runtime.
Most times, there is a requirement to adjust values assigned to configuration parameters.
ConfigMaps are a Kubernetes mechanism that let you inject configuration data into application
{{< glossary_tooltip text="pods" term_id="pod" >}}.

The ConfigMap concept allow you to decouple configuration artifacts from image content to
keep containerized applications portable. For example, you can download and run the same
{{< glossary_tooltip text="container image" term_id="image" >}} to spin up containers for 
the purposes of local development, system test, or running a live end-user workload.

This page provides a series of usage examples demonstrating how to create ConfigMaps and
configure Pods using data stored in ConfigMaps.

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

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

You need to have the `wget` tool installed. If you have a different tool
such as `curl`, and you do not have `wget`, you will need to adapt the
step that downloads example data.

<!-- steps -->

## Create a ConfigMap

You can use either `kubectl create configmap` or a ConfigMap generator in `kustomization.yaml`
to create a ConfigMap.

### Create a ConfigMap using `kubectl create configmap`

Use the `kubectl create configmap` command to create ConfigMaps from
[directories](#create-configmaps-from-directories), [files](#create-configmaps-from-files),
or [literal values](#create-configmaps-from-literal-values):

```shell
kubectl create configmap <map-name> <data-source>
```

where \<map-name> is the name you want to assign to the ConfigMap and \<data-source> is the
directory, file, or literal value to draw the data from.
The name of a ConfigMap object must be a valid
[DNS subdomain name](/docs/concepts/overview/working-with-objects/names#dns-subdomain-names).

When you are creating a ConfigMap based on a file, the key in the \<data-source> defaults to
the basename of the file, and the value defaults to the file content.

You can use [`kubectl describe`](/docs/reference/generated/kubectl/kubectl-commands/#describe) or
[`kubectl get`](/docs/reference/generated/kubectl/kubectl-commands/#get) to retrieve information
about a ConfigMap.

#### Create a ConfigMap from a directory {#create-configmaps-from-directories}

You can use `kubectl create configmap` to create a ConfigMap from multiple files in the same
directory. When you are creating a ConfigMap based on a directory, kubectl identifies files
whose filename is a valid key in the directory and packages each of those files into the new
ConfigMap. Any directory entries except regular files are ignored (for example: subdirectories,
symlinks, devices, pipes, and more).

{{< note >}}
Each filename being used for ConfigMap creation must consist of only acceptable characters,
which are: letters (`A` to `Z` and `a` to `z`), digits (`0` to `9`), '-', '_', or '.'.
If you use `kubectl create configmap` with a directory where any of the file names contains
an unacceptable character, the `kubectl` command may fail.

The `kubectl` command does not print an error when it encounters an invalid filename.
{{< /note >}}

Create the local directory:

```shell
mkdir -p configure-pod-container/configmap/
```

Now, download the sample configuration and create the ConfigMap:

```shell
# Download the sample files into `configure-pod-container/configmap/` directory
wget https://kubernetes.io/examples/configmap/game.properties -O configure-pod-container/configmap/game.properties
wget https://kubernetes.io/examples/configmap/ui.properties -O configure-pod-container/configmap/ui.properties

# Create the ConfigMap
kubectl create configmap game-config --from-file=configure-pod-container/configmap/
```

The above command packages each file, in this case, `game.properties` and `ui.properties`
in the `configure-pod-container/configmap/` directory into the game-config ConfigMap. You can
display details of the ConfigMap using the following command:

```shell
kubectl describe configmaps game-config
```

The output is similar to this:
```
Name:         game-config
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
game.properties:
----
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
ui.properties:
----
color.good=purple
color.bad=yellow
allow.textmode=true
how.nice.to.look=fairlyNice
```

The `game.properties` and `ui.properties` files in the `configure-pod-container/configmap/`
directory are represented in the `data` section of the ConfigMap.

```shell
kubectl get configmaps game-config -o yaml
```
The output is similar to this:

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2022-02-18T18:52:05Z
  name: game-config
  namespace: default
  resourceVersion: "516"
  uid: b4952dc3-d670-11e5-8cd0-68f728db1985
data:
  game.properties: |
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30    
  ui.properties: |
    color.good=purple
    color.bad=yellow
    allow.textmode=true
    how.nice.to.look=fairlyNice    
```

#### Create ConfigMaps from files

You can use `kubectl create configmap` to create a ConfigMap from an individual file, or from
multiple files.

For example,

```shell
kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties
```

would produce the following ConfigMap:

```shell
kubectl describe configmaps game-config-2
```

where the output is similar to this:

```
Name:         game-config-2
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
game.properties:
----
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
```

You can pass in the `--from-file` argument multiple times to create a ConfigMap from multiple
data sources.

```shell
kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties --from-file=configure-pod-container/configmap/ui.properties
```

You can display details of the `game-config-2` ConfigMap using the following command:

```shell
kubectl describe configmaps game-config-2
```

The output is similar to this:

```
Name:         game-config-2
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
game.properties:
----
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
ui.properties:
----
color.good=purple
color.bad=yellow
allow.textmode=true
how.nice.to.look=fairlyNice
```

Use the option `--from-env-file` to create a ConfigMap from an env-file, for example:

```shell
# Env-files contain a list of environment variables.
# These syntax rules apply:
#   Each line in an env file has to be in VAR=VAL format.
#   Lines beginning with # (i.e. comments) are ignored.
#   Blank lines are ignored.
#   There is no special handling of quotation marks (i.e. they will be part of the ConfigMap value)).

# Download the sample files into `configure-pod-container/configmap/` directory
wget https://kubernetes.io/examples/configmap/game-env-file.properties -O configure-pod-container/configmap/game-env-file.properties
wget https://kubernetes.io/examples/configmap/ui-env-file.properties -O configure-pod-container/configmap/ui-env-file.properties

# The env-file `game-env-file.properties` looks like below
cat configure-pod-container/configmap/game-env-file.properties
enemies=aliens
lives=3
allowed="true"

# This comment and the empty line above it are ignored
```

```shell
kubectl create configmap game-config-env-file \
       --from-env-file=configure-pod-container/configmap/game-env-file.properties
```

would produce a ConfigMap. View the ConfigMap:

```shell
kubectl get configmap game-config-env-file -o yaml
```

the output is similar to:
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2019-12-27T18:36:28Z
  name: game-config-env-file
  namespace: default
  resourceVersion: "809965"
  uid: d9d1ca5b-eb34-11e7-887b-42010a8002b8
data:
  allowed: '"true"'
  enemies: aliens
  lives: "3"
```

Starting with Kubernetes v1.23, `kubectl` supports the `--from-env-file` argument to be
specified multiple times to create a ConfigMap from multiple data sources.

```shell
kubectl create configmap config-multi-env-files \
        --from-env-file=configure-pod-container/configmap/game-env-file.properties \
        --from-env-file=configure-pod-container/configmap/ui-env-file.properties
```

would produce the following ConfigMap:

```shell
kubectl get configmap config-multi-env-files -o yaml
```

where the output is similar to this:
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2019-12-27T18:38:34Z
  name: config-multi-env-files
  namespace: default
  resourceVersion: "810136"
  uid: 252c4572-eb35-11e7-887b-42010a8002b8
data:
  allowed: '"true"'
  color: purple
  enemies: aliens
  how: fairlyNice
  lives: "3"
  textmode: "true"
```

#### Define the key to use when creating a ConfigMap from a file

You can define a key other than the file name to use in the `data` section of your ConfigMap
when using the `--from-file` argument:

```shell
kubectl create configmap game-config-3 --from-file=<my-key-name>=<path-to-file>
```

where `<my-key-name>` is the key you want to use in the ConfigMap and `<path-to-file>` is the
location of the data source file you want the key to represent.

For example:

```shell
kubectl create configmap game-config-3 --from-file=game-special-key=configure-pod-container/configmap/game.properties
```

would produce the following ConfigMap:
```
kubectl get configmaps game-config-3 -o yaml
```

where the output is similar to this:
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2022-02-18T18:54:22Z
  name: game-config-3
  namespace: default
  resourceVersion: "530"
  uid: 05f8da22-d671-11e5-8cd0-68f728db1985
data:
  game-special-key: |
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30    
```

#### Create ConfigMaps from literal values

You can use `kubectl create configmap` with the `--from-literal` argument to define a literal
value from the command line:

```shell
kubectl create configmap special-config --from-literal=special.how=very --from-literal=special.type=charm
```

You can pass in multiple key-value pairs. Each pair provided on the command line is represented
as a separate entry in the `data` section of the ConfigMap.

```shell
kubectl get configmaps special-config -o yaml
```

The output is similar to this:
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2022-02-18T19:14:38Z
  name: special-config
  namespace: default
  resourceVersion: "651"
  uid: dadce046-d673-11e5-8cd0-68f728db1985
data:
  special.how: very
  special.type: charm
```

### Create a ConfigMap from generator

You can also create a ConfigMap from generators and then apply it to create the object
in the cluster's API server.
You should specify the generators in a `kustomization.yaml` file within a directory.

#### Generate ConfigMaps from files

For example, to generate a ConfigMap from files `configure-pod-container/configmap/game.properties`

```shell
# Create a kustomization.yaml file with ConfigMapGenerator
cat <<EOF >./kustomization.yaml
configMapGenerator:
- name: game-config-4
  options:
    labels:
      game-config: config-4
  files:
  - configure-pod-container/configmap/game.properties
EOF
```

Apply the kustomization directory to create the ConfigMap object:

```shell
kubectl apply -k .
```
```
configmap/game-config-4-m9dm2f92bt created
```

You can check that the ConfigMap was created like this:

```shell
kubectl get configmap
```
```
NAME                       DATA   AGE
game-config-4-m9dm2f92bt   1      37s
```

and also:

```shell
kubectl describe configmaps/game-config-4-m9dm2f92bt
```
```
Name:         game-config-4-m9dm2f92bt
Namespace:    default
Labels:       game-config=config-4
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","data":{"game.properties":"enemies=aliens\nlives=3\nenemies.cheat=true\nenemies.cheat.level=noGoodRotten\nsecret.code.p...

Data
====
game.properties:
----
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
Events:  <none>
```

Notice that the generated ConfigMap name has a suffix appended by hashing the contents. This
ensures that a new ConfigMap is generated each time the content is modified.

#### Define the key to use when generating a ConfigMap from a file

You can define a key other than the file name to use in the ConfigMap generator.
For example, to generate a ConfigMap from files `configure-pod-container/configmap/game.properties`
with the key `game-special-key`

```shell
# Create a kustomization.yaml file with ConfigMapGenerator
cat <<EOF >./kustomization.yaml
configMapGenerator:
- name: game-config-5
  options:
    labels:
      game-config: config-5
  files:
  - game-special-key=configure-pod-container/configmap/game.properties
EOF
```

Apply the kustomization directory to create the ConfigMap object.
```shell
kubectl apply -k .
```
```
configmap/game-config-5-m67dt67794 created
```

#### Generate ConfigMaps from literals

This example shows you how to create a `ConfigMap` from two literal key/value pairs:
`special.type=charm` and `special.how=very`, using Kustomize and kubectl. To achieve
this, you can specify the `ConfigMap` generator. Create (or replace)
`kustomization.yaml` so that it has the following contents:

```yaml
---
# kustomization.yaml contents for creating a ConfigMap from literals
configMapGenerator:
- name: special-config-2
  literals:
  - special.how=very
  - special.type=charm
```

Apply the kustomization directory to create the ConfigMap object:
```shell
kubectl apply -k .
```
```
configmap/special-config-2-c92b5mmcf2 created
```

## Interim cleanup

Before proceeding, clean up some of the ConfigMaps you made:

```bash
kubectl delete configmap special-config
kubectl delete configmap env-config
kubectl delete configmap -l 'game-config in (config-4,config-5)'
```

Now that you have learned to define ConfigMaps, you can move on to the next
section, and learn how to use these objects with Pods.

---

## Define container environment variables using ConfigMap data

### Define a container environment variable with data from a single ConfigMap

1. Define an environment variable as a key-value pair in a ConfigMap:

   ```shell
   kubectl create configmap special-config --from-literal=special.how=very
   ```

2. Assign the `special.how` value defined in the ConfigMap to the `SPECIAL_LEVEL_KEY`
   environment variable in the Pod specification.

   {{% code_sample 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`.

### Define container environment variables with data from multiple ConfigMaps

As with the previous example, create the ConfigMaps first.
Here is the manifest you will use:

{{% code_sample file="configmap/configmaps.yaml" %}}

* Create the ConfigMap:

  ```shell
  kubectl create -f https://kubernetes.io/examples/configmap/configmaps.yaml
  ```

* Define the environment variables in the Pod specification.

  {{% code_sample 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`.

  Once you're happy to move on, delete that Pod and ConfigMap:
  ```shell
  kubectl delete pod dapi-test-pod --now
  kubectl delete configmap special-config
  kubectl delete configmap env-config
  ```

## Configure all key-value pairs in a ConfigMap as container environment variables

* Create a ConfigMap containing multiple key-value pairs.

  {{% code_sample 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.

  {{% code_sample 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`.

  Once you're happy to move on, delete that Pod:
  ```shell
  kubectl delete pod dapi-test-pod --now
  ```

## Use ConfigMap-defined environment variables in Pod commands

You can use ConfigMap-defined environment variables in the `command` and `args` of a container
using the `$(VAR_NAME)` Kubernetes substitution syntax.

For example, the following Pod manifest:

{{% code_sample file="pods/pod-configmap-env-var-valueFrom.yaml" %}}

Create that Pod, by running:

```shell
kubectl create -f https://kubernetes.io/examples/pods/pod-configmap-env-var-valueFrom.yaml
```

That pod produces the following output from the `test-container` container:
```shell
kubectl logs dapi-test-pod
```

```
very charm
```

Once you're happy to move on, delete that Pod:
```shell
kubectl delete pod dapi-test-pod --now
```

## 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.

The examples in this section refer to a ConfigMap named `special-config`:

{{% code_sample 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.
This adds the ConfigMap data to the directory specified as `volumeMounts.mountPath` (in this
case, `/etc/config`). The `command` section lists directory files with names that match the
keys in ConfigMap.

{{% code_sample file="pods/pod-configmap-volume.yaml" %}}

Create the Pod:

```shell
kubectl create -f https://kubernetes.io/examples/pods/pod-configmap-volume.yaml
```

When the pod runs, the command `ls /etc/config/` produces the output below:

```
SPECIAL_LEVEL
SPECIAL_TYPE
```

Text data is exposed as files using the UTF-8 character encoding. To use some other
character encoding, use `binaryData`
(see [ConfigMap object](/docs/concepts/configuration/configmap/#configmap-object) for more details).

{{< note >}}
If there are any files in the `/etc/config` directory of that container image, the volume
mount will make those files from the image inaccessible.
{{< /note >}}

Once you're happy to move on, delete that Pod:
```shell
kubectl delete pod dapi-test-pod --now
```

### Add ConfigMap data to a specific path in the Volume

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`.

{{% code_sample file="pods/pod-configmap-volume-specific-key.yaml" %}}

Create the Pod:

```shell
kubectl create -f https://kubernetes.io/examples/pods/pod-configmap-volume-specific-key.yaml
```

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 >}}

Delete that Pod:
```shell
kubectl delete pod dapi-test-pod --now
```

### Project keys to specific paths and file permissions

You can project keys to specific paths. Refer to the corresponding section in the [Secrets](/docs/tasks/inject-data-application/distribute-credentials-secure/#project-secret-keys-to-specific-file-paths) guide for the syntax.  
You can set POSIX permissions for keys. Refer to the corresponding section in the [Secrets](/docs/tasks/inject-data-application/distribute-credentials-secure/#set-posix-permissions-for-secret-keys) guide for the syntax.

### Optional references

A ConfigMap reference may be marked _optional_. If the ConfigMap is non-existent, the mounted
volume will be empty. If the ConfigMap exists, but the referenced key is non-existent, the path
will be absent beneath the mount point. See [Optional ConfigMaps](#optional-configmaps) for more
details.

### Mounted ConfigMaps are updated automatically

When a mounted ConfigMap is updated, the projected content is eventually updated too.
This applies in the case where an optionally referenced ConfigMap comes into
existence after a pod has started.

Kubelet checks whether the mounted ConfigMap is fresh on every periodic sync. However,
it uses its local TTL-based cache for getting the current value of the ConfigMap. As a
result, the total delay from the moment when the ConfigMap is updated to the moment
when new keys are projected to the pod can be as long as kubelet sync period (1
minute by default) + TTL of ConfigMaps cache (1 minute by default) in kubelet. You
can trigger an immediate refresh by updating one of the pod's annotations.

{{< note >}}
A container using a ConfigMap as a [subPath](/docs/concepts/storage/volumes/#using-subpath)
volume will not receive ConfigMap updates.
{{< /note >}}

<!-- discussion -->

## Understanding ConfigMaps and Pods

The ConfigMap API resource stores configuration data as key-value pairs. The data can be consumed
in pods or provide the configurations for system components such as controllers. ConfigMap is
similar to [Secrets](/docs/concepts/configuration/secret/), but provides a means of working
with strings that don't contain sensitive information. Users and system components alike can
store configuration data in ConfigMap.

{{< note >}}
ConfigMaps should reference properties files, not replace them. Think of the ConfigMap as
representing something similar to the Linux `/etc` directory and its contents. For example,
if you create a [Kubernetes Volume](/docs/concepts/storage/volumes/) from a ConfigMap, each
data item in the ConfigMap is represented by an individual file in the volume.
{{< /note >}}

The ConfigMap's `data` field contains the configuration data. As shown in the example below,
this can be simple (like individual properties defined using `--from-literal`) or complex
(like configuration files or JSON blobs defined using `--from-file`).

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: 2016-02-18T19:14:38Z
  name: example-config
  namespace: default
data:
  # example of a simple property defined using --from-literal
  example.property.1: hello
  example.property.2: world
  # example of a complex property defined using --from-file
  example.property.file: |-
    property.1=value-1
    property.2=value-2
    property.3=value-3    
```

When `kubectl` creates a ConfigMap from inputs that are not ASCII or UTF-8, the tool puts
these into the `binaryData` field of the ConfigMap, and not in `data`. Both text and binary
data sources can be combined in one ConfigMap.

If you want to view the `binaryData` keys (and their values) in a ConfigMap, you can run
`kubectl get configmap -o jsonpath='{.binaryData}' <name>`.

Pods can load data from a ConfigMap that uses either `data` or `binaryData`.

## Optional ConfigMaps

You can mark a reference to a ConfigMap as _optional_ in a Pod specification.
If the ConfigMap doesn't exist, the configuration for which it provides data in the Pod
(for example: environment variable, mounted volume) will be empty.
If the ConfigMap exists, but the referenced key is non-existent the data is also empty.

For example, the following Pod specification marks an environment variable from a ConfigMap
as optional:

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: ["/bin/sh", "-c", "env"]
      env:
        - name: SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
              name: a-config
              key: akey
              optional: true # mark the variable as optional
  restartPolicy: Never
```

If you run this pod, and there is no ConfigMap named `a-config`, the output is empty.
If you run this pod, and there is a ConfigMap named `a-config` but that ConfigMap doesn't have
a key named `akey`, the output is also empty. If you do set a value for `akey` in the `a-config`
ConfigMap, this pod prints that value and then terminates.

You can also mark the volumes and files provided by a ConfigMap as optional. Kubernetes always
creates the mount paths for the volume, even if the referenced ConfigMap or key doesn't exist. For
example, the following Pod specification marks a volume that references a ConfigMap as optional:

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: ["/bin/sh", "-c", "ls /etc/config"]
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: no-config
        optional: true # mark the source ConfigMap as optional
  restartPolicy: Never
```



## Restrictions

- You must create the `ConfigMap` object before you reference it in a Pod
  specification. Alternatively, mark the ConfigMap reference as `optional` in the Pod spec (see
  [Optional ConfigMaps](#optional-configmaps)). If you reference a ConfigMap that doesn't exist
  and you don't mark the reference as `optional`, the Pod won't start. Similarly, references
  to keys that don't exist in the ConfigMap will also prevent the Pod from starting, unless
  you mark the key references as `optional`.

- If you use `envFrom` to define environment variables from ConfigMaps, keys that are considered
  invalid will be skipped. The pod will be allowed to start, but the invalid names will be
  recorded in the event log (`InvalidVariableNames`). The log message lists each skipped
  key. For example:

  ```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.
  ```

- ConfigMaps reside in a specific {{< glossary_tooltip term_id="namespace" >}}.
  Pods can only refer to ConfigMaps that are in the same namespace as the Pod.

- You can't use ConfigMaps for
  {{< glossary_tooltip text="static pods" term_id="static-pod" >}}, because the
  kubelet does not support this.

## {{% heading "cleanup" %}}

Delete the ConfigMaps and Pods that you made:

```bash
kubectl delete configmaps/game-config configmaps/game-config-2 configmaps/game-config-3 \
               configmaps/game-config-env-file
kubectl delete pod dapi-test-pod --now

# You might already have removed the next set
kubectl delete configmaps/special-config configmaps/env-config
kubectl delete configmap -l 'game-config in (config-4,config-5)'
```

Remove the `kustomization.yaml` file that you used to generate the ConfigMap:

```bash
rm kustomization.yaml
```

If you created a directory `configure-pod-container` and no longer need it, you should remove that too,
or move it into the trash can / deleted files location.

```bash
rm -r configure-pod-container
```

## {{% heading "whatsnext" %}}

* Follow a real world example of
  [Configuring Redis using a ConfigMap](/docs/tutorials/configuration/configure-redis-using-configmap/).
* Follow an example of [Updating configuration via a ConfigMap](/docs/tutorials/configuration/updating-configuration-via-a-configmap/).