Environment Variables in Kubernetes

# ... pod's specification
spec:
  containers:
    - image: webapp-image
      # ...
      env:
        - name: VAR_NAME
          value: VAR_VALUE
          
        # Examples:
        
        # 1. play key-value
        - name: APP_COLOR
          value: ping

        # 2. ConfigMap
        - name: APP_COLOR
          valueFrom:
            configMapKeyRef:

        # 3. Secret
        - name: APP_COLOR
          valueFrom:
            secretKeyRef: