kubectl cp: Usage, Options & Common CI Errors

Copy files into or out of a running container.

kubectl cp moves files between the local filesystem and a container, or between two containers. In CI it is used to pull a generated artifact (a coverage report, a built file) out of a pod, or push a fixture in.

What it does

kubectl cp SRC DEST copies files, where a pod path is written namespace/pod:/path. It works by streaming a tar archive through the container, so the target container must have a tar binary on its PATH. -c selects the container in a multi-container pod.

Common usage

kubectl cp my-pod:/app/report.xml ./report.xml      # out of the pod
kubectl cp ./fixture.json my-pod:/tmp/fixture.json   # into the pod
kubectl cp ./data my-ns/my-pod:/data -c app          # explicit ns + container
kubectl cp my-pod:/var/log ./logs                    # a whole directory

Common errors in CI

"tar: not found" or "error: ... exec: \"tar\": executable file not found" is the defining failure: cp needs tar inside the container, and distroless/scratch/minimal images do not ship it. Work around it by adding tar to a debug image, or stream instead: kubectl exec my-pod -- cat /app/report.xml > report.xml for a single file. Also note cp does not preserve into a path whose parent does not exist - create the directory first, and beware that absolute vs relative path mistakes silently copy to the wrong place.

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