如何在 kubernetes pod 的容器中设置用户名？

Question

I have a following pod yaml to run a pod with security context where runAsUser and runAsGroup are set.

apiVersion: v1
kind: Pod
metadata:
  name: test
spec:
  containers:
  - name: test
    image: ubuntu:18.04
    command: ["sleep", "10d"]
    securityContext:
      runAsUser: 1002
      runAsGroup: 2002

When I exec into the container, it says:

$ k exec -it test -- bash
groups: cannot find name for group ID 2002
I have no name!@test:/$

whoami command is also not working:

I have no name!@test:/$ whoami
whoami: cannot find name for user ID 1002

Here I need to set username for given uid(uid is not fixed so can't create image with a specific username).

Does kubernetes provide any option to set username?

Answer 1

No. The username (if any) is determined by looking up the numeric user ID in the container's /etc/passwd file (if any), and Kubernetes doesn't try to modify that file.

There aren't really any consequences to the user ID not existing in /etc/passwd , beyond getting this cosmetic error message in the unusual case of a debugging shell. Filesystem permissions are set and enforced only based on the numeric user and group IDs. So, for example, if you mount a PersistentVolumeClaim with an additional fsGroup: setting, that's based only on a numeric group ID, and again, it's irrelevant whether or not that actually exists in the container's /etc/groups file.