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 [pods](https://kubernetes-io-vnext-staging.netlify.app/docs/concepts/workloads/pods/). 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 [container image](https://kubernetes-io-vnext-staging.netlify.app/docs/reference/glossary/?all=true#term-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. Before you begin ---------------- 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: * [Killercoda](https://killercoda.com/playgrounds/scenario/kubernetes) * [Play with Kubernetes](https://labs.play-with-k8s.com/) 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. 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): kubectl create configmap

where is the name you want to assign to the ConfigMap and 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](https://kubernetes-io-vnext-staging.netlify.app/docs/concepts/overview/working-with-objects/names/#dns-subdomain-names). When you are creating a ConfigMap based on a file, the key in the defaults to the basename of the file, and the value defaults to the file content. You can use [`kubectl describe`](https://kubernetes-io-vnext-staging.netlify.app/docs/reference/generated/kubectl/kubectl-commands/#describe) or [`kubectl get`](https://kubernetes-io-vnext-staging.netlify.app/docs/reference/generated/kubectl/kubectl-commands/#get) to retrieve information about a ConfigMap. #### Create a ConfigMap from a directory 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). Create the local directory: mkdir -p configure-pod-container/configmap/ Now, download the sample configuration and create the ConfigMap: # 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: kubectl describe configmaps game-config The output is similar to this: Name: game-config Namespace: default Labels: Annotations: 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. kubectl get configmaps game-config -o yaml The output is similar to this: 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, kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties would produce the following ConfigMap: kubectl describe configmaps game-config-2 where the output is similar to this: Name: game-config-2 Namespace: default Labels: Annotations: 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. 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: kubectl describe configmaps game-config-2 The output is similar to this: Name: game-config-2 Namespace: default Labels: Annotations: 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: # 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 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: kubectl get configmap game-config-env-file -o yaml the output is similar to: 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. 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: kubectl get configmap config-multi-env-files -o yaml where the output is similar to this: 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 `--f

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