When running a build inside a docker container, some commands don't work because they rely on the user being properly set. For example, ssh doesn't work with the following error:

No user exists for uid 150.

I think this could be solved by append to passwd on container startup, something like this (untested, for proof of concept):

if [ "$(id -u)" != "0" ]; then

    echo "jenkins:x:$(id -u):$(id -g):Jenkins:${HOME}:/sbin/nologin" >> /etc/passwd

fi