build-push-hosts

name	build-push-hosts
description	Build NixOS host closures deterministically and push them to Attic.
compatibility	opencode
metadata	{"audience":"maintainers","repo":"nixos","workflow":"deploy-cache"}

What I do

I build one or more nixosConfigurations.<host>.config.system.build.toplevel closures and push them into the configured Attic cache.

I use the repo's deterministic nixos cache subcommand.

When to use me

Use me when the user wants to:

• prebuild host system closures on a stronger machine
• populate the Attic cache before host-local deploys
• push all normal hosts, or a named subset, into Attic

Default behavior

• work from nix develop
• push to Attic cache main
• if no hosts are passed, use nixos cache interactive multi-select
• build and push hosts sequentially for deterministic logs

Workflow

1. Confirm the target cache and host scope.

   • Default cache: main
   • Default host scope: interactive selection when no hosts were passed
   • Respect explicit host arguments from the user or command

2. Build each host individually with a 60 minute timeout each.

   • Large hosts (with Ollama, CUDA, Electron, Qt, WebKit etc.) can take 10+ minutes to download inputs and compile.
   • Run each host in a separate nix develop --command nixos cache <host> invocation so each has its own timeout context and does not block others.

3. Run the repo command.

   • Dry-run first when the user is asking what would happen
   • Real run when the user asks to build/push

4. Report clearly.

   • Which hosts were built
   • Which cache they were pushed to
   • Any host failures, with the first failing command

Commands

Dry-run with interactive host selection:

nix develop --command nixos cache --dry-run

Build and push with interactive host selection:

nix develop --command nixos cache

Build and push specific hosts:

nix develop --command nixos cache hub kit pow

Build and push all hosts without prompting:

nix develop --command nixos cache --all

Include iso too:

nix develop --command nixos cache --all --include-iso

Guardrails

• Do not bypass the repo nixos cache wrapper with ad hoc build/push commands unless the user asks.
• Do not deploy or switch hosts here; this skill is only for build-and-push.
• Do not silently include iso unless explicitly requested.
• Do not commit or push git changes unless the user explicitly asks.