Kubernetes Volumes: Mounting ConfigMaps and Secrets¶

category: Kubernetes
tags: volumes, configmap, secret, mount, pods

Main Topic 1¶

Volumes in Kubernetes are used to mount external data (config files, secrets, storage) into pods. They're essential for injecting files at runtime.

Subtopic A: Mount ConfigMap as File¶

volumes:
  - name: config-volume
    configMap:
      name: backend-config
      items:
        - key: application.yml
          path: application.yml

volumeMounts:
  - name: config-volume
    mountPath: /config
    readOnly: true

Subtopic B: Mount Secret as File¶

volumes:
  - name: secret-volume
    secret:
      secretName: db-secret

volumeMounts:
  - name: secret-volume
    mountPath: /etc/secrets
    readOnly: true

Main Topic 2¶

Use Cases¶

Applications that require config or secret files on disk
Avoid passing sensitive data via env vars
Reading application.yml, .pem, .env, .crt files

Key Concepts Summary¶

Files, not env vars - Some tools expect files, not variables
Read-only by default - Best to enforce this explicitly
Fine-grained control - items: allows selective mounting

Best Practices / Tips¶

Use only needed keys - Don’t mount entire config if only one file is needed.
Match paths carefully - Apps must read from correct file paths.
Enforce readOnly - Avoid accidental overwrite or tampering.

Common Issues / Troubleshooting¶

Problem 1¶

Symptom: App can’t find the file
Cause: Wrong mount path or missing file key
Solution: Ensure correct items: and mountPath