Add: workflow update nixos

content/posts/workflow-update-nixos-en.md

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+date = '2025-10-13T00:00:01+02:00'
+draft = false
+title = 'NixOs update workflow'
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+
+I update my NixOS systems once a week, on Sundays.
+Gone are the days of frantic updates on Arch Linux for a package that changes twice a day!
+
+I start on my desktop machine by updating the repositories and freezing the versions in Git.
+It’s my anchor point — the one that validates a successful update.
+
+```
+nix flake update
+git add flake.lock
+git commit -m "FLAKE: update"
+git push origin master
+```
+
+Then I update the desktop itself, with a bit of cleanup.
+I keep eight days of generations, which means I always have a complete, stable version from the previous week.
+
+```
+sudo nixos-rebuild switch --flake $HOME/nixos-config#pennsardin --show-trace --keep-going
+nix-collect-garbage --delete-older-than 8d
+sudo nix-collect-garbage --delete-older-than 8d
+```
+Next comes the server.
+I start by pulling the flake update, then rebuild:
+
+```
+ssh dunoz@terre-neuvas
+cd nixos-config
+git pull
+sudo nixos-rebuild switch --flake $HOME/nixos-config#terre-neuvas --show-trace --keep-going
+nix-collect-garbage --delete-older-than 8d
+sudo nix-collect-garbage --delete-older-than 8d
+```
+
+## And if it breaks?
+
+If an update goes wrong, I simply revert to the previous flake version on the desktop.
+
+```
+git revert HEAD
+git push origin master
+sudo nixos-rebuild switch --flake $HOME/nixos-config#pennsardin
+```
+
+Then on then server:
+
+```
+git pull
+sudo nixos-rebuild switch --flake $HOME/nixos-config#pennsardin
+```
+
+I could use rollback, but that would create a mismatch between the Git repository and the machines — something I don’t want.
+The Git repo is the sanctuary, the one that governs everything.