nix-dev

Otto's Nix configuration. The commands below terraform a fresh machine from scratch.

Bootstrap a new machine

# Install nix (multi-user daemon install)
sh <(curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install) --yes --daemon

# Activate nix in the current shell
. /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh

# Enable flakes + nix-command, and build derivations in parallel, for this session
export NIX_CONFIG="experimental-features = nix-command flakes
max-jobs = auto"

# Bootstrap with home-manager (pick the config that matches the machine below)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#ow20@server

# Make the newly installed zsh the default shell
sudo usermod -s $(which zsh) $(whoami)

The max-jobs = auto line builds derivations in parallel. The configs set nix.settings.max-jobs = "auto", but that only takes effect after the first activation, and Nix otherwise defaults to max-jobs = 1 (fully serial). Since a cold bootstrap builds ~75 local derivations (a config-specific neovim wrapper plus plugins that miss the public cache), setting it in NIX_CONFIG for the bootstrap session roughly halves wall-clock on a multi-core machine. Every rebuild after the first picks it up from the activated config automatically.

Available configurations

The flake exposes one homeConfigurations output per machine. Swap the #... selector on the bootstrap command for any of these:

# macOS laptop (aarch64-darwin)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#ottowhite@Ottos-MacBook-Pro.local

# NixOS laptop (x86_64-linux)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#otto@nixos

# Server, ow20 user (x86_64-linux)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#ow20@server

# Server, ansible user (x86_64-linux)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#ansible@server

# CSG server, ow20 user (x86_64-linux)
nix run home-manager/master -- switch --flake github:ottowhite/nix-dev#ow20@csgserver

All nix run/nix flake invocations assume the NIX_CONFIG export from the bootstrap step above is in effect (experimental-features = nix-command flakes, plus max-jobs = auto). This matches the style used in modules/zsh.nix, so after the first switch the hms / hmsr shell helpers are available.

Measuring cold-build cost

Makefile.dev has two targets that measure a from-scratch build without touching the real /nix/store (they build into a throwaway chroot store that is torn down on exit). Override CONFIG=<name> for a config other than the default ow20@server:

# Timed cold build — total wall-clock only
make -f Makefile.dev cold-build

# Timed breakdown — attributes wall-clock to eval / download / local-build
# phases and lists the slowest downloads and derivations
make -f Makefile.dev cold-build-breakdown