My proudest (and also maybe least proud at the same time) was writing a BASH script that was able to successfully replicate a complex server environment that had been previously built by contractors for an essential service that we needed to re-deploy, both for growing regions, but also to resolve a possible security issue due to how the contractors had deployed it. I had to basically reverse engineer every aspect of the service, built a deployment backend that I triggered, and did all of it in a fully-automated way that would break in known manners if it failed. That script went on to be used to deploy the entire service globally to ~12 regions on hundreds of servers.

The thing I'm most known for in that company was when I was working night-shift support and a customer called in with a server that had one of the drives fail on a Windows box, and apparently had decided it was worth saving $1/mo to not have backups. Because it was night-shift and nothing else crazy was going on, I decided to delve deep and I managed to get things back up by rebuilding their partition table by hand in a hex editor and avoiding some specific bad blocks so we could copy the data to a second drive DCOPS temporarily installed in the server, then we reinstalled the box and I migrated all their data back and brought their website back up. It took me around 9 hours, and at the end of it, the customer called in to complain about how long their site had been down, gave me the whole spiel. I had ended up staying late, so handed things off to the most senior person on the next shift that had a chance of understanding what I had done, and when I got done transferring the call I walked up two floors to talk to them directly to warm handoff and could hear the customer screaming through their headset from 3 cubes away. I became a legend for doing the most thankless task anyone had ever done for a customer in support.