Why I can't get into the container running "kubernetes-dashboard"?-CodePudding

I was trying to get into kubernetes-dashboard Pod, but I keep getting this error:

C:\Users\USER>kubectl exec -n kubernetes-dashboard  kubernetes-dashboard-66c887f759-bljtc -it -- sh
OCI runtime exec failed: exec failed: unable to start container process: exec: "sh": executable file not found in $PATH: unknown
command terminated with exit code 126

The Pod is running normally and I can access the Kubernetes UI via the browser. But I was getting some issues getting it running before, and I wanted to get inside the pod to run some commands, but I always get the same error mentioned above.

When I try the same command with a pod running nginx for example, it works:

C:\Users\USER>kubectl exec my-nginx -it -- sh
/ # ls
bin                   home                  proc                  sys
dev                   lib                   root                  tmp
docker-entrypoint.d   media                 run                   usr
docker-entrypoint.sh  mnt                   sbin                  var
etc                   opt                   srv
/ # exit

Any explanation, please?

CodePudding user response：

Prefix the command to run with /bin so your updated command will look like:

kubectl exec -n kubernetes-dashboard  <POD_NAME> -it -- /bin/sh

The reason you're getting that error is because Git in Windows slightly modifies the MSYS that changes command args. Generally using the command /bin/sh or /bash/bash works universally.

CodePudding user response：

That error message means literally what it says: there is no sh or any other shell in the container. There's no particular requirement that a container have a shell, and if a Docker image is built FROM scratch (as the Kubernetes dashboard image is) or a "distroless" image, it just may not contain one.

In most cases you shouldn't need to "enter a container", and you should use kubectl exec (or docker exec) sparingly if at all. This is doubly true in Kubernetes: it's not just that changes you make manually will get lost when the container exits, but also that in Kubernetes you typically have multiple replicas that you can't manually edit all at once, and also that in some cases the cluster can delete and recreate a Pod outside of your control.