Cant ssh into running container containing portainer through docker exec
Containers may or may not include a shell, depending on how the container was built. Looking at docker hub it looks like the base image may be based on a &quot;scratch&quot; image, meaning that there may not be anything in the container other than the code needed to run the portainer service. The image layers here also suggest this is the case.
If you want a shell, you may want to use the portainer/portainer-ca:alpine tag. That should give you a container with a full alpine os (and the shell you are looking for). As another note, you may want to try using /bin/sh instead as not all images provide a bash shell.