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Configuration Management

In Kubernetes, it is important to separate application code from configuration. This makes applications more portable and easier to manage. Kubernetes provides two main resources for managing configuration: ConfigMaps and Secrets.

ConfigMaps​

A ConfigMap is a Kubernetes object used to store non-confidential configuration data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume.

Creating a ConfigMap​

You can create a ConfigMap from a file, a directory, or from literal values.

  • From a file:

    kubectl create configmap my-config --from-file=my-config.properties

  • From literal values:

    kubectl create configmap my-config --from-literal=app.name=my-app --from-literal=app.version=1.0

Using a ConfigMap in a Pod​

Here is an example of how to mount a ConfigMap as a volume in a Pod:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
    - name: my-container
      image: my-image
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: my-config

Secrets​

A Secret is a Kubernetes object used to store sensitive information, such as passwords, OAuth tokens, and ssh keys. Secrets are similar to ConfigMaps, but they are stored in a more secure way.

Creating a Secret​

You can create a Secret from a file or from literal values.

  • From literal values: 
    kubectl create secret generic my-secret --from-literal=username=my-user --from-literal=password='my-password'
    The values are automatically base64 encoded.

Using a Secret in a Pod​

Here is an example of how to use a Secret as an environment variable in a Pod:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
    - name: my-container
      image: my-image
      env:
        - name: MY_USERNAME
          valueFrom:
            secretKeyRef:
              name: my-secret
              key: username
        - name: MY_PASSWORD
          valueFrom:
            secretKeyRef:
              name: my-secret
              key: password