Add a tarball of the manual to Hydra build outputs

[fricklerhandwerk]

While trying to host the Nix manual on nix.dev instead of nixos.org I'm running into the following problem:

I want to automatically deploy the latest build of the manual from each of the selected release branches. But since Hydra may have failed builds, after updating the remote source, the deployment will either have to rebuild all of Nix (and likely fail), or I'll have to manually pin it to some state that is cached, both of which is a huge waste of time.

Proposal

Since Hydra offers a latest URL to each jobset, adding a build output that produces a tarball with the manual would solve the problem very elegantly. Consumers (in this case nix.dev) can fetch the tarball directly from Hydra, always getting the latest successful build.

Alternatives

Have a similar branching system like Nixpkgs, where the actual release branches are those that pass tests.

[thufschmitt]

Have a similar branching system like Nixpkgs, where the actual release branches are those that pass tests.

Ideally we'd rather have a proper CI system preventing us from merging broken stuff :)

I talked to @grahamc some times ago about having some proper Hydra support for the PRs, and he seemed to imply that it wasn't too hard to get (although I guess he doesn't have time to do it himself). Maybe @NixOS/infra could be of help here

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-11-10-nix-team-meeting-minutes-102/35379/1

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2024-10-16-nix-team-meeting-minutes-187/54835/1