Solution by iamchanghyunpark

“I checked the pid value in the log and checked if there was a running process with the same pid, and no there was none.
I’m guessing this is because of the unexpected powerdown, and unicorn.pid was not properly cleared.
My solution was simple”

docker-compose exec gitlab bash
vi log/unicorn.stderr.log # remove the value (which is the pid), save and exit
exit # from the bash shell of the gitlab container

#Now restart the containers
docker-compose down
docker-compose up -d