Build AUR packages in container (systemd-nspawn) and then install on host (Arch Linux)

yayc.sh

#!/usr/bin/env bash
set -euo pipefail

# chmod +x /usr/local/bin/yayc

# Config
CONTAINER_NAME="aur-builder"
CONTAINER_DIR="/var/lib/machines/$CONTAINER_NAME"
PKG_OUT="/var/cache/aur-builder"  # here are .zst packages
HOST_USER="$(id -un)"

RED="\e[31m"
GREEN="\e[32m"
YELLOW="\e[33m"
BLUE="\e[34m"
BOLD="\e[1m"
RESET="\e[0m"

usage() {
    echo "Usage: $0 [--rebuild] [packages...]"
    echo "  --rebuild  Rebuild the container from scratch"
    exit 1
}

# Create/use container
build_container() {
    echo -e "${GREEN}${BOLD}[*] Creating container${RESET} ${BLUE}$CONTAINER_NAME...${RESET}"
    sudo rm -rf "$CONTAINER_DIR"
    sudo mkdir $CONTAINER_DIR
    sudo pacstrap -K -c "$CONTAINER_DIR" base base-devel git --noconfirm

    sudo systemd-nspawn -D "$CONTAINER_DIR" --machine="$CONTAINER_NAME" \
        bash -c "useradd -m build && echo 'build ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/build"
    echo -e "${GREEN}${BOLD}[*] Container created.${RESET}"
}

# Check args
REBUILD=0
PKGS=()

for arg in "$@"; do
    case "$arg" in
        --rebuild) REBUILD=1 ;;
        -h|--help) usage ;;
        *) PKGS+=("$arg") ;;
    esac
done

if [[ $REBUILD -eq 1 ]] || ! sudo test -d "$CONTAINER_DIR"; then
    build_container
    sudo sed -i "s/^ParallelDownloads = [0-9]\+$/ParallelDownloads = 1/" "$CONTAINER_DIR/etc/pacman.conf"
fi

if [[ ${#PKGS[@]} -eq 0 ]]; then
    echo "No packages to build."
    exit 0
fi

# Create folder for package
sudo mkdir -p "$PKG_OUT"

echo -e "${GREEN}${BOLD}[*] Building packages:${RESET} ${BLUE}${PKGS[*]} ${RESET}"

# Run yay in container
sudo systemd-nspawn -D "$CONTAINER_DIR" --machine="$CONTAINER_NAME" \
    --bind "$PKG_OUT:/output" \
    bash -c "
        set -e
        if ! id build >/dev/null 2>&1; then useradd -m build; fi
        su - build -c '
            if ! command -v yay >/dev/null; then
                git clone https://aur.archlinux.org/yay.git
                cd yay && makepkg -si --noconfirm
            fi
            mkdir /home/build/tmp
            yay -S --noconfirm --builddir /home/build/tmp --mflags --skipinteg ${PKGS[*]}
            sudo mv /home/build/tmp/**/*.zst /output/
            rm -rf /home/build/tmp
        '
    "

# Install on host
latest_pkg=$(ls -t "$PKG_OUT"/*.zst | head -n1)

echo -e "${GREEN}${BOLD}[*] Installing packages on host...${RESET} ${BLUE} $latest_pkg ${RESET}"
sudo pacman -U --noconfirm "$latest_pkg"
sudo ls $latest_pkg
# sudo rm $latest_pkg

# echo -e "${GREEN}${BOLD}[*] Building packages...${RESET}"
# echo -e "${YELLOW}Warning:${RESET} something happened"
# echo -e "${RED}${BOLD}Error:${RESET} failed to build"