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ConfigMaps

Updated Apr 07, 2022 ·

Overview​

ConfigMaps store configuration data separately from container images, making applications portable. The data is stored as key-value pairs.

  • Data is stored as key-value pairs.
  • Pods reference ConfigMaps to access data.
  • Can be mounted as volumes or set as environment variables.

ConfigMaps can be created from:

  • Environment variable files (key-value pairs).
  • Files or directories (keys are filenames, values are file contents).
  • Command-line literals (key-value pairs).
  • YAML manifest files of kind ConfigMap.

ConfigMaps are namespace-specific, meaning only Pods in the same Namespace can use them.

Injecting ConfigMap into Pods​

Example ConfigMap:

apiVersion: v1
kind: ConfigMap
metadata:
  name: USERNAME
data:
  DB_USERNAME: "admin"
  DB_PASSWORD: "password123"

After the ConfigMap is created, the next step is to inject it to the Pod.

apiVersion: v1
kind: Pod
metadata:
  name: myapp
spec:
  containers:
  - name: myapp
    image: <Image>
    envFrom:
      - configMapRef:
          name: USERNAME

Ways to Inject ConfigMap into Pods​

As environment variables:

envFrom:
  - configMapRef:
      name: USERNAME

As a single environment variable:

env:
  - name: DB_Username
    valueFrom:
      configMapKeyRef:
        name: USERNAME
        key: DB_USERNAME

Mount ConfigMap as a volume:

volumes:
  - name: app-configMap-volumes
    configMap:
      name: USERNAME