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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

1. Use only needed keys - Don’t mount entire config if only one file is needed.
2. Match paths carefully - Apps must read from correct file paths.
3. 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

References / Further Reading

• K8s Volumes
• ConfigMap Volume Docs

Last updated: 2025-08-26 20:00 UTC