ConfigMaps allow you to decouple configuration artifacts from image content to keep containerized applications portable. This page provides a series of usage examples demonstrating how to create ConfigMaps and configure Pods using data stored in ConfigMaps.
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 data source corresponds to a key-value pair in the ConfigMap, where
* key = the file name or the key you provided on the command line, and
* value = the file contents or the literal value you provided on the command line.
You can use [`kubectl describe`](/docs/user-guide/kubectl/{{page.version}}/#describe) or
[`kubectl get`](/docs/user-guide/kubectl/{{page.version}}/#get) to retrieve information
about a ConfigMap.
### Create ConfigMaps from directories
You can use `kubectl create configmap` to create a ConfigMap from multiple files in the same directory.
combines the contents of the `docs/user-guide/configmap/kubectl/` directory
```shell
ls docs/user-guide/configmap/kubectl/
game.properties
ui.properties
```
into the following ConfigMap:
```shell
kubectl describe configmaps game-config
Name: game-config
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
game.properties: 158 bytes
ui.properties: 83 bytes
```
The `game.properties` and `ui.properties` files in the `docs/user-guide/configmap/kubectl/` directory are represented in the `data` section of the ConfigMap.
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.
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.
1. Use `envFrom` to define all of the ConfigMap's data as Pod environment variables. The key from the ConfigMap becomes the environment variable name in the Pod.
You can use ConfigMap-defined environment variables in the `command` section of the Pod specification using the `$(VAR_NAME)` Kubernetes substitution syntax.
As explained in [Configure Containers Using a ConfigMap](/docs/tasks/configure-pod-container/configmap/), 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.
When a ConfigMap already being consumed in a volume is updated, projected keys are eventually updated as well. Kubelet is checking whether the mounted ConfigMap is fresh on every periodic sync. However, it is using 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 + ttl of ConfigMaps cache in kubelet.
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
kind: ConfigMap
apiVersion: v1
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
1. You must create a ConfigMap before referencing it in a Pod specification (unless you mark the ConfigMap as "optional"). If you reference a ConfigMap that doesn't exist, the Pod won't start. Likewise, references to keys that don't exist in the ConfigMap will prevent the pod from starting.
1. 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
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.
1. 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.
