Thanks. As I understand it, any ruby version mismatch is not about your OS but about the docker image. Of course the docker image should be internally consistent.
The memory issue which causes git pull to fail is important to fix first, but I don’t have any ideas. Just possibly it’s worth trying
git fetch --depth=1
to see if that can work.
I think it’s always worth checking machine config:
df -h /
free
Also, maybe