kubernetes: kubectl cp does not return an error when the source file doesn't exist

What happened:

Running kubectl cp /some/file/that/doesnt/exist pod:/tmp silently fails if that source file doesn’t exist.

What you expected to happen:

I expected kubectl to exit with a non-zero status code and to print a standard error message like so:

ls: /some/file/that/doesnt/exist: No such file or directory

How to reproduce it (as minimally and precisely as possible):

Find any running pod, try to copy a non-existent file:

pod=$(kubectl get pod -o jsonpath='{ .items[0].metadata.name }')
kubectl cp /some/file/that/doesnt/exist $pod:/tmp
echo $? # echos 0 when it should echo 1

Anything else we need to know?:

kubectl cp existing-file $pod:/some/dir/that/doesnt/exist works right. For example:

$ ls -l xyz
-rw-r--r--  1 dpk  staff  1663 Jun 10 17:26 xyz
$ kubectl cp xyz $pod:/some/dir/that/doesnt/exist
tar: /some/dir/that/doesnt: Cannot open: No such file or directory
$ echo $?
2

I’m sure this has something to do with the fact that kubectl uses tar under the hood. However, tar itself will report an error if you try to extract a file that doesn’t exist, so maybe this is just a matter of not including the to-be-extracted-path(s) on the end of the tar command line.

This might be fixed by appending src.File (or rather the basename of it) to the end of the array here: https://github.com/kubernetes/kubernetes/blob/master/pkg/kubectl/cmd/cp/cp.go#L251 (haven’t tried it).

Environment:

• Kubernetes version (use kubectl version):

Client Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.1", GitCommit:"b7394102d6ef778017f2ca4046abbaa23b88c290", GitTreeState:"clean", BuildDate:"2019-04-08T17:11:31Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.1", GitCommit:"b7394102d6ef778017f2ca4046abbaa23b88c290", GitTreeState:"clean", BuildDate:"2019-04-08T17:02:58Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"linux/amd64"}

and

Server Version: version.Info{Major:"1", Minor:"13+", GitVersion:"v1.13.6-gke.0", GitCommit:"14c9138d6fb5b57473e270fe8a2973300fbd6fd6", GitTreeState:"clean", BuildDate:"2019-05-08T16:22:55Z", GoVersion:"go1.11.5b4", Compiler:"gc", Platform:"linux/amd64"}

• Cloud provider or hardware configuration: docker-for-desktop 2.0.4.1 (34207) and GKE running 1.13.6-gke-0
• OS (e.g: cat /etc/os-release): macOS 10.14.5
• Kernel (e.g. uname -a): Darwin nacho.local 18.6.0 Darwin Kernel Version 18.6.0: Thu Apr 25 23:16:27 PDT 2019; root:xnu-4903.261.4~2/RELEASE_X86_64 x86_64
• Install tools: Installed docker from dmg, using the included kubectl
• Network plugin and version (if this is a network-related bug):
• Others: