groups: cannot find name for group ID XYZ

[gadiego92]

Hi, I think I'm facing some issue in the latest releases. My issue is with groups command.

When I run the groups command in a Dockerfile I get the error:

groups: cannot find name for group ID XYZ

Let's use the following Dockerfile to see the behavior:

FROM ubuntu

RUN groupadd -g 1234 group123

RUN useradd -u 54321 -g 1234 user123

USER user123

RUN groups

Actual behavior
In the releases 1.9.0 (8cab37f84a44) and 1.9.1 (dcfa90c317b5) this is the output when I run the executor command with the previous Dockerfile:

/workspace # executor --dockerfile "Dockerfile" --no-push
INFO[0000] Retrieving image manifest ubuntu
INFO[0000] Retrieving image ubuntu from registry index.docker.io
INFO[0001] Built cross stage deps: map[]
INFO[0001] Retrieving image manifest ubuntu
INFO[0001] Returning cached image manifest
INFO[0001] Executing 0 build triggers
INFO[0001] Building stage 'ubuntu' [idx: '0', base-idx: '-1']
INFO[0001] Unpacking rootfs as cmd RUN groupadd -g 1234 group123 requires it.
INFO[0002] RUN groupadd -g 1234 group123
INFO[0002] Initializing snapshotter ...
INFO[0002] Taking snapshot of full filesystem...
INFO[0003] Cmd: /bin/sh
INFO[0003] Args: [-c groupadd -g 1234 group123]
INFO[0003] Running: [/bin/sh -c groupadd -g 1234 group123]
INFO[0003] Taking snapshot of full filesystem...
INFO[0003] RUN useradd -u 54321 -g 1234 user123
INFO[0003] Cmd: /bin/sh
INFO[0003] Args: [-c useradd -u 54321 -g 1234 user123]
INFO[0003] Running: [/bin/sh -c useradd -u 54321 -g 1234 user123]
INFO[0003] Taking snapshot of full filesystem...
INFO[0003] USER user123
INFO[0003] Cmd: USER
INFO[0003] RUN groups
INFO[0003] Cmd: /bin/sh
INFO[0003] Args: [-c groups]
INFO[0003] Util.Lookup returned: &{Uid:54321 Gid:1234 Username:user123 Name: HomeDir:/home/user123}
INFO[0003] Performing slow lookup of group ids for user123
INFO[0003] Running: [/bin/sh -c groups]
groups: cannot find name for group ID 54321
54321 group123
error building image: error building stage: failed to execute command: waiting for process to exit: exit status 1

Expected behavior
In the releases 1.8.1 (e1e8f684a8d2) and the previous ones, the behavior is the following:

/workspace # executor --dockerfile "Dockerfile" --no-push
INFO[0000] Retrieving image manifest ubuntu
INFO[0000] Retrieving image ubuntu from registry index.docker.io
INFO[0001] Built cross stage deps: map[]
INFO[0001] Retrieving image manifest ubuntu
INFO[0001] Returning cached image manifest
INFO[0001] Executing 0 build triggers
INFO[0001] Unpacking rootfs as cmd RUN groupadd -g 1234 group123 requires it.
INFO[0002] RUN groupadd -g 1234 group123
INFO[0002] Taking snapshot of full filesystem...
INFO[0003] cmd: /bin/sh
INFO[0003] args: [-c groupadd -g 1234 group123]
INFO[0003] Running: [/bin/sh -c groupadd -g 1234 group123]
INFO[0003] Taking snapshot of full filesystem...
INFO[0003] RUN useradd -u 54321 -g 1234 user123
INFO[0003] cmd: /bin/sh
INFO[0003] args: [-c useradd -u 54321 -g 1234 user123]
INFO[0003] Running: [/bin/sh -c useradd -u 54321 -g 1234 user123]
INFO[0003] Taking snapshot of full filesystem...
INFO[0003] USER user123
INFO[0003] cmd: USER
INFO[0003] RUN groups
INFO[0003] cmd: /bin/sh
INFO[0003] args: [-c groups]
INFO[0003] util.Lookup returned: &{Uid:54321 Gid:1234 Username:user123 Name: HomeDir:/home/user123}
INFO[0003] performing slow lookup of group ids for user123
INFO[0003] Running: [/bin/sh -c groups]
group123
INFO[0003] Taking snapshot of full filesystem...
INFO[0003] No files were changed, appending empty layer to config. No layer added to image.
INFO[0003] Skipping push to container registry due to --no-push flag

Additional Information
I have done some testing and I would say the issue is in the commit: aad03dc

I built Kaniko images locally without that commit (aad03dc) and it seems it worked fine. That's why I think there is an issue in the mentioned commit.

[gadiego92]

It looks like Kaniko thinks by default that the UID (54321 in the example) is also a GID.
So when it tries to resolve the GIDs it cannot find 54321 because indeed it is not a GID.