nixpkgs PR build bot

This bot is essentially a private ofborg / nixpkgs-review bot, but much easier to host. It builds all packages mentioned in the commits of a nixpkgs pull request, or alternatively all packages impacted by the changes.

Send me a message if you would like to access a demo instance of the bot.

Configuration

You can configure the bot by setting certain environment variables. The bot will process $TASKS PRs in parallel, with $JOBS jobs each, with each job getting $CORES cores. $NIXPKGS_DIRECTORY must be set to a jj-colocated checkout of nixpkgs. $SUDO_PASSWORD is used to switch to the nobody user when invoking Nix. $WASTEBIN is the URL to a wastebin instance. $CONTACT, $DESCRIPTION are displayed in the bot's introduction message. $GH_TOKEN is only used for fetching evaluation artifacts, use a fine-grained access token with public read-only permissions. $CONFIG is where certain settings are stored, if not set those features don't work. $CROSS is used for automatic cross builds, if enabled.

.env template, with the defaults explicitly set:

export TELEGRAM_BOT_TOKEN=
export LANG=
export NIXPKGS_PR_BUILD_BOT_NIXPKGS_DIRECTORY=
export NIXPKGS_PR_BUILD_BOT_SUDO_PASSWORD=
export NIXPKGS_PR_BUILD_BOT_CORES=0
export NIXPKGS_PR_BUILD_BOT_JOBS=6
export NIXPKGS_PR_BUILD_BOT_TASKS=10
export NIXPKGS_PR_BUILD_BOT_WASTEBIN=https://paste.fliegendewurst.eu
export NIXPKGS_PR_BUILD_BOT_CONTACT="this bot's owner"
export NIXPKGS_PR_BUILD_BOT_DESCRIPTION="the nixpkgs revision currently checked out"
export NIXPKGS_PR_BUILD_BOT_GH_TOKEN=
export NIXPKGS_PR_BUILD_BOT_CONFIG=
export NIXPKGS_PR_BUILD_BOT_CROSS=aarch64-multiplatform

NixOS config

Adapt path to .env, host platform and user.

systemd.services.prBuildBot = {
  description = "nixpkgs PR build bot";
  script = ''
    export PATH="$PATH:/run/wrappers/bin"
    jj --version
    git --version
    nix-shell --version
    sudo --version
    source .../path/to/.env
    exec ${lib.getExe nixpkgs-pr-build-bot.packages.x86_64-linux.nixpkgs-pr-build-bot}
  '';
  serviceConfig = {
    User = "xxx";
    Type = "simple";
    OOMPolicy = "continue";
  };
  path = with pkgs; [
    jujutsu
    git
    pkgs.nix
  ];
  wants = [ "network-online.target" ];
  wantedBy = [ "network-online.target" ];
  after = [ "network-online.target" ];
};

Usage

Start a chat with the bot. The bot will reply with a small introduction.

TL;DR: send /pr <num> to build mentioned packages. Use /full <num> to build all changed packages (equivalent to nixpkgs-review).

Maintenance

To clean up testing branches use this script. Recommend backing up your nixpkgs working directory first, in case of jj log failures.

#!/bin/sh

set -euo pipefail

time_now=$(date '+%s')
for c in $(git for-each-ref --sort=committerdate 'refs/heads/nixpkgs-*' --format='%(refname)')
do
    time_touched=$(git show -s --format="%ct" "$c")
    [[ 172800 -lt $(($time_now - $time_touched)) ]] || break
    git show -s --format="%ci $c" "$c"
    num=$(echo $c | rg --only-matching '\d+')
    revs=$(jj log --no-pager --no-graph -T 'change_id ++ " "' -r "..nixpkgs-$num ~ ..@")
    jj abandon $revs
    jj bookmark delete "nixpkgs-$num"
done