rootsongjc-pr-20170815
This commit is contained in:
Jimmy Song
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---
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approvers:
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- eparis
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- pmorie
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title: Configure Containers Using a ConfigMap
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---
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{% capture overview %}
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This page shows you how to configure an application using a ConfigMap. ConfigMaps allow you to decouple configuration artifacts from image content to keep containerized applications portable.
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{% endcapture %}
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{% capture prerequisites %}
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* {% include task-tutorial-prereqs.md %}
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{% endcapture %}
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{% capture steps %}
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## Use kubectl to create a ConfigMap
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Use the `kubectl create configmap` command to create configmaps from [directories](#creating-configmaps-from-directories), [files](#creating-configmaps-from-files), or [literal values](#creating-configmaps-from-literal-values):
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```shell
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kubectl create configmap <map-name> <data-source>
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```
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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.
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The data source corresponds to a key-value pair in the ConfigMap, where
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* key = the file name or the key you provided on the command line, and
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* value = the file contents or the literal value you provided on the command line.
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You can use [`kubectl describe`](/docs/user-guide/kubectl/v1.6/#describe) or [`kubectl get`](/docs/user-guide/kubectl/v1.6/#get) to retrieve information about a ConfigMap. The former shows a summary of the ConfigMap, while the latter returns the full contents of the ConfigMap.
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### Create ConfigMaps from directories
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You can use `kubectl create configmap` to create a ConfigMap from multiple files in the same directory.
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For example:
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```shell
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kubectl create configmap game-config --from-file=docs/user-guide/configmap/kubectl
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```
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combines the contents of the `docs/user-guide/configmap/kubectl/` directory
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```shell
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ls docs/user-guide/configmap/kubectl/
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game.properties
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ui.properties
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```
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into the following ConfigMap:
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```shell
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kubectl describe configmaps game-config
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Name: game-config
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Namespace: default
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Labels: <none>
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Annotations: <none>
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Data
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====
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game.properties: 158 bytes
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ui.properties: 83 bytes
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```
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The `game.properties` and `ui.properties` files in the `docs/user-guide/configmap/kubectl/` directory are represented in the `data` section of the ConfigMap.
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```shell
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kubectl get configmaps game-config -o yaml
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```
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```yaml
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apiVersion: v1
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data:
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game.properties: |
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enemies=aliens
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lives=3
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enemies.cheat=true
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enemies.cheat.level=noGoodRotten
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secret.code.passphrase=UUDDLRLRBABAS
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secret.code.allowed=true
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secret.code.lives=30
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ui.properties: |
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color.good=purple
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color.bad=yellow
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allow.textmode=true
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how.nice.to.look=fairlyNice
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kind: ConfigMap
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metadata:
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creationTimestamp: 2016-02-18T18:52:05Z
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name: game-config
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namespace: default
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resourceVersion: "516"
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selfLink: /api/v1/namespaces/default/configmaps/game-config-2
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uid: b4952dc3-d670-11e5-8cd0-68f728db1985
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```
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### Create ConfigMaps from files
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You can use `kubectl create configmap` to create a ConfigMap from an individual file, or from multiple files.
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For example,
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```shell
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kubectl create configmap game-config-2 --from-file=docs/user-guide/configmap/kubectl/game.properties
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```
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would produce the following ConfigMap:
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```shell
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kubectl describe configmaps game-config-2
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Name: game-config-2
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Namespace: default
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Labels: <none>
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Annotations: <none>
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Data
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====
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game.properties: 158 bytes
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```
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You can pass in the `--from-file` argument multiple times to create a ConfigMap from multiple data sources.
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```shell
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kubectl create configmap game-config-2 --from-file=docs/user-guide/configmap/kubectl/game.properties --from-file=docs/user-guide/configmap/kubectl/ui.properties
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```
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```shell
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kubectl describe configmaps game-config-2
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Name: game-config-2
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Namespace: default
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Labels: <none>
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Annotations: <none>
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Data
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====
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game.properties: 158 bytes
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ui.properties: 83 bytes
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```
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#### Define the key to use when creating a ConfigMap from a file
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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:
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```shell
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kubectl create configmap game-config-3 --from-file=<my-key-name>=<path-to-file>
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```
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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.
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For example:
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```shell
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kubectl create configmap game-config-3 --from-file=game-special-key=docs/user-guide/configmap/kubectl/game.properties
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kubectl get configmaps game-config-3 -o yaml
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```
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```yaml
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apiVersion: v1
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data:
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game-special-key: |
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enemies=aliens
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lives=3
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enemies.cheat=true
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enemies.cheat.level=noGoodRotten
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secret.code.passphrase=UUDDLRLRBABAS
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secret.code.allowed=true
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secret.code.lives=30
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kind: ConfigMap
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metadata:
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creationTimestamp: 2016-02-18T18:54:22Z
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name: game-config-3
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namespace: default
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resourceVersion: "530"
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selfLink: /api/v1/namespaces/default/configmaps/game-config-3
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uid: 05f8da22-d671-11e5-8cd0-68f728db1985
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```
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### Create ConfigMaps from literal values
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You can use `kubectl create configmap` with the `--from-literal` argument to define a literal value from the command line:
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```shell
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kubectl create configmap special-config --from-literal=special.how=very --from-literal=special.type=charm
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```
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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.
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```shell
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kubectl get configmaps special-config -o yaml
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```
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```yaml
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apiVersion: v1
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data:
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special.how: very
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special.type: charm
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kind: ConfigMap
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metadata:
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creationTimestamp: 2016-02-18T19:14:38Z
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name: special-config
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namespace: default
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resourceVersion: "651"
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selfLink: /api/v1/namespaces/default/configmaps/special-config
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uid: dadce046-d673-11e5-8cd0-68f728db1985
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```
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{% endcapture %}
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{% capture discussion %}
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## Understanding ConfigMaps
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ConfigMaps allow you to decouple configuration artifacts from image content to keep containerized applications portable.
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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.
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**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.
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{: .note}
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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`.
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```yaml
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kind: ConfigMap
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apiVersion: v1
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metadata:
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creationTimestamp: 2016-02-18T19:14:38Z
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name: example-config
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namespace: default
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data:
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# example of a simple property defined using --from-literal
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example.property.1: hello
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example.property.2: world
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# example of a complex property defined using --from-file
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example.property.file: |-
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property.1=value-1
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property.2=value-2
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property.3=value-3
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```
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{% endcapture %}
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{% capture whatsnext %}
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* See [Using ConfigMap Data in Pods](/docs/tasks/configure-pod-container/configure-pod-configmap).
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* Follow a real world example of [Configuring Redis using a ConfigMap](/docs/tutorials/configuration/configure-redis-using-configmap/).
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{% endcapture %}
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{% include templates/task.md %}
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