Error: error: unexpected EOF in kubectl cp

Symptom:

   When we run kubectl cp  <container>:/filename  /tmp/filename  . It error out

 error: unexpected EOF

Solution:

    The most possible reason is kubectl cp need tar in the container to work.

see details via kubectl cp --help  

Copy files and directories to and from containers.
Examples:
  # !!!Important Note!!!
  # Requires that the 'tar' binary is present in your container
  # image.  If 'tar' is not present, 'kubectl cp' will fail.

  # Copy /tmp/foo_dir local directory to /tmp/bar_dir in a remote pod in the default namespace
  kubectl cp /tmp/foo_dir <some-pod>:/tmp/bar_dir

  # Copy /tmp/foo local file to /tmp/bar in a remote pod in a specific container
  kubectl cp /tmp/foo <some-pod>:/tmp/bar -c <specific-container>

  # Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace <some-namespace>
  kubectl cp /tmp/foo <some-namespace>/<some-pod>:/tmp/bar

  # Copy /tmp/foo from a remote pod to /tmp/bar locally
  kubectl cp <some-namespace>/<some-pod>:/tmp/foo /tmp/bar
Options:
  -c, --container='': Container name. If omitted, the first container in the pod will be chosen
      --no-preserve=false: The copied file/directory's ownership and permissions will not be preserved in the container
Usage:
  kubectl cp <file-spec-src> <file-spec-dest> [options]