Challenge ·Medium

Copy Config Files from a Running Pod

Omkar Shelke
by  Omkar Shelke · on
KubernetesLinux
A Deployment is running in the platform namespace with 3 replicas. Each pod has configuration files at /app/config/. Copy those files to /home/laborant/config/ on the local machine.
#ckad#cka#kubectl#configmap#tar

Scenario

The platform namespace runs a config-service Deployment with 3 replicas. The Deployment mounts a ConfigMap (app-config) as a volume at /app/config/ inside each pod. The ConfigMap holds four runtime configuration files:

/app/config/
├── database.conf
├── feature-flags.conf
├── logging.conf
└── server.conf

The service is exposed via a ClusterIP Service — not reachable from outside the cluster.

Task

Copy the four files mounted from the app-config ConfigMap at /app/config/ inside any running pod in the platform namespace to /home/laborant/config/ on dev-machine.

The destination directory /home/laborant/config/ already exists.

Important

Do not modify the Deployment, ConfigMap, or Service.

Hint 1 — Find a pod to work with

You need a running pod name from the platform namespace. List the pods and note any one with Running status — you will use its name in the next step.

kubectl get pods -n platform

Documentation

Hint 2 — Try the obvious copy command first

kubectl has a built-in subcommand for copying files between a pod and your local machine. Try it against the /app/config/ path and observe what happens:

kubectl cp platform/<pod-name>:/app/config/ /home/laborant/config/

Look carefully at the output. Are the files actually written to /home/laborant/config/? What does the output tell you about why?

Documentation

Hint 3 — Use a tar pipe through kubectl exec

ConfigMap volumes do not write regular files to disk — kubectl cp skips the symlinks it sees at /app/config/, so no named files appear at the top level of your destination. Confirm the symlink structure first:

kubectl exec -n platform <pod-name> -- ls -la /app/config/

The l at the start of each permission string (lrwxrwxrwx) means symlink.

The fix is to run tar inside the pod yourself via kubectl exec, then pipe the archive out to a local tar -x. When tar runs inside the pod, the kernel resolves every symlink transparently before handing bytes to tar, so the archive contains real file content. A local tar then extracts those bytes onto dev-machine.

Think about:

  • how to write archive bytes to stdout from inside a pod
  • how to strip the leading path components so files land directly in /home/laborant/config/

Documentation

⚒ Test Cases

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