Recently, I’ve been working on a service that runs on a lot of VM’s across different locations. If I have a new service build, updating all of the running instances quickly became a bit of a pain. I have to log in to every VM (in some cases through a VPN) and then do a manual upgrade. Now, there are probably tools that already exist for this type of use case but since I’m still learning Go at the moment, I thought this would be a good exercise.
Basically, this is a Windows service that has an http endpoint that accepts a file upload (in this case, a new version of itself). The service then saves this file, calls the
MoveFileEx API with the
MOVEFILE_DELAY_UNTIL_REBOOT flag, then reboots the system. I also added a simple client (still written in Go) that will upload the file.
With these tools, I can now update all the running service instances with a script.
Full source code here.---
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