Is there a way to use Raspberry Pi 4 B as a git server with gitlab installation and make is accessible from anywhere? from a home connection and in a secure way?
I think it is possible. Probably as secure as it can be because it’s a public facing service. You could make it more secure by only allow a few ips to access it for example the ip block from your workplace.
Hi!
Yes, it’s possible, although depending on what You want to do with it, the hardware may not meet the requirements. If it’s for You and/or a small team, no problem.
Regarding security, that will depend on the server admin. You will have to do a search on how to harden Your server 
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I’m not sure about a git server however with the new pi 4 being a lot more powerful than the 3 b+ I’ve been investigating running one as a web server to host my portfolio, a WordPress blog, and file server which according to the official pi forum responses that I’ve had, this is definitely within its capabilities.
My advice would be to post your question on that forum too 
Hi, I would suggest looking for some more lightweight Git servers like Gitea instead of gitlab as it’s quite heavy-weight. As for remote access - check out my project Webhook Relay. I am using it heavily myself to access various servers like Node-RED, Drone.io and Home Assistant that are running on Intel NUC server (I moved to Intel NUC from RPI 3B+ for CI/CD).
@cryptographicfool What you can do is install OpenVPN on your home router or a server on your home network. That will give you a more secure connection to your self-hosted Gitlab server on your LAN. With OpenVPN on your router would really be the easiest way. Some routers allow you to install just the OpenVPN configuration file and voila! you have a secure connection to your home network.