docker-compose.yml

# Compose file which provides automagic building of NixOS SD images for AArch64 systems.
# Use together with `docker-compose.emulation.yml` if a transparent emulation layer is required.

# Comes out with sane defaults, feel free to configure as needed.
# NOTE: the configuration used to build NixOS resides in the parent directory as `sd-image.nix`

version: "3"

services:
  # Main container, requires no elevated privileges to run. Builds NixOS.
  build-nixos:
    build:
      context: build-nixos
      args:
        IMAGE_BASE: $IMAGE_BASE
        NIXPKGS_URL: "https://github.com/nixos/nixpkgs"
        NIXPKGS_BRANCH: "nixos-23.11"
    working_dir: /home/nixos
    # Main command line, left here so it can be changed easily. The container will:
    # - setup the environment. This includes adding the Nix executables to $PATH, along with the
    #   registration of an EXIT handler which will send a signal to `cleanup-qemu` when done.
    # - wait until `setup-qemu` is done by attempting to run an AArch64 binary. This works out of
    #   the box if running on AArch64.
    # - build the actual SD image.
    # - copy it to /build, which points by default to this directory.
    command: [sh, -c, ". setup-env && \
                       sh wait-for-qemu.sh && \
                       nix-build \
                         -A config.system.build.sdImage \
                         --option system aarch64-linux \
                         --option sandbox false \
                         -I nixos-config=/build/config/sd-image.nix \
                         nixpkgs/nixos/default.nix && \
                       chmod u+w result/sd-image/* && sudo cp result/sd-image/* /build"]
    volumes:
    - ..:/build