feat(cachix): auto-push tower/leod builds to soft-nix cache#150
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This was referenced May 29, 2026
Wires the upstream services.cachix-watch-store NixOS module via a new flake module so local builds on tower and leod push freshly-built store paths to soft-nix.cachix.org. aaron is intentionally out of scope (see plans/cachix-push-from-aaron.md): Determinate Nix already owns the post-build-hook on darwin. Per-host write tokens limit blast radius if one machine is compromised. The committed .age files are placeholders to keep CI green; replace each with a real cachix write token via \`agenix -e\` before deploying.
Lateral SSH between machines is unrestricted, so a per-host token does not meaningfully reduce blast radius — compromising tower lets the attacker read leod's secret too. Single shared token is simpler.
The previous extraction was overkill for a single attribute set, and the applicability matches nixos-workstation exactly: tower and leod use it, aaron uses the cross-platform workstation module, pi is not a workstation.
Statix flagged repeated `services` keys after inlining cachix-watch-store. Merge the three sibling assignments into one attribute set. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
etrobert
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May 30, 2026
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Summary
services.cachix-watch-storeinsidemodules/nixos-workstation.nixso local builds on tower and leod automatically push freshly-built store paths to soft-nix.cachix.org. CI already does this; this extends the same behavior to interactive builds.cachix-token.ageencrypted for both hosts. Per-host tokens were rejected because lateral SSH between machines is unrestricted — compromising one host already gives access to the other.nixos-workstationrather than a separate module: applicability matches exactly (tower + leod), and one services block isn't worth its own file.post-build-hookslot on darwin. Seeplans/cachix-push-from-aaron.md(local) for the deferred plan.Before merging
The committed
cachix-token.ageis a placeholder (encrypted "replace with real token" string). It keeps CI green but won't decrypt to a usable cachix token. Steps to finish:Writescope).agenix -e secrets/cachix-token.age— paste the token.cachix-watch-store-agentsystemd service will start and begin pushing.Test plan
nix flake check --all-systems --no-buildpassessystemctl status cachix-watch-store-agentshows running on both hostsnix build nixpkgs#hello --rebuild); confirm new path on the soft-nix dashboard