I worked on a monolith with 100+ devs working on it daily. Merging was automated as well for us, and a few unit tests were run on a production env — basically t

I worked on a monolith with 100+ devs working on it daily. Merging was automated as well for us, and a few unit tests were run on a production env — basically tests that asserted an engineer didn’t do anything stupid like add an infinite loop, or any of the other dozens things engineers had done that caused downtime. Deployment was done by running a script that took a lock, monitored the deployment progress, then released the lock. Sometimes you’d run the script and see people who hadn’t deployed yet, so you’d send them a message and ask if it was good to deploy. Sometimes they would say no if they found a last minute bug, so they would deploy your code for you. Surprisingly, coordination isn’t that difficult. Humans are pretty good at talking to each other.