Overleaf is composed of multiple different processes which all write log files to /var/log/overleaf/ (/var/log/sharelatex/ for versions 4.x and earlier). It is possible to mount this directory or any file inside this directory outside of the container for easier access.

If an error occurs in any of the processes it will be written to the respective log file such as /var/log/overleaf/web.log (/var/log/sharelatex/web.log for versions 4.x and earlier).

Overleaf Toolkit users can have a look at the logs inside the container using bin/logs:

$ bin/logs -f web

You can also look at the logs for multiple services at once:

$ bin/logs -f filestore docstore web clsi

It is possible to see who and when a project is loaded with the following command

grep "join project request" /var/log/overleaf/real-time.log

This will give both the timestamp, user_id and project_id.