On face value it doesn’t look too different to dockcheck. What you’ve described (CLI, read-only, no auto updates, sends notifications via channel of your choosing) sounds exactly like how my dockcheck is set up. Were you aware of dockcheck and if so, how would you say your project differs?

Honestly, no — I hadn’t come across dockcheck before now, so thanks for pointing it out. I didn’t do a big survey of what’s out there; I just had an itch (notify-only update checks across a few hosts, with a proxy, no auto-updating) and nothing I’d tried quite fit how I wanted it, so I ended up writing my own. Sounds like dockcheck lands in a similar space — I’ll take a look at how it does things. Not trying to claim mine’s better; different paths to the same problem.