.envrc

# First, check for a supported nix version
MSNV="2.14.0"
OURNV=$(nix eval --raw --expr "builtins.nixVersion")
vercomp=$(nix eval --expr "builtins.compareVersions \"${OURNV}\" \"${MSNV}\"")
if [ "$vercomp" = "-1" ]; then
  cat <<-EOF

ERROR: Your Nix is older than the "Minimum Supported Nix Version" (MSNV).

  Your Nix: ${OURNV}
      MSNV: ${MSNV}

This build can't be guaranteed to succeed correctly or be free of bugs that
the system may otherwise guarantee.

If you can't freely upgrade Nix, then please open a discussion if you would
like the minimum supported Nix version to be adjusted.

EOF
  [ -z "$NIX_ALLOW_UNSUPPORTED_VERSION" ] && exit 1
  printf "NOTICE: Continuing despite unsupported Nix version.\n\n"
fi

# Next, check that the user is trusted, so the out-of-band binary cache
# can be used (this is required even with ca-derivations)
if ! nix show-config | grep -q "trusted-users =.*${USER}" ; then
  cat <<-EOF

ERROR: Your user account must be part of the 'trusted-users' setting in your
Nix configuration to use this project. Please add '$USER' to the
'trusted-users' setting in either:

  - your /etc/nixos/configuration.nix
  - your /etc/nix/nix.conf

EOF
  exit 1
fi

# Make sure the user has [ref:ca-derivations] enabled; otherwise, the ability to fetch
# derivations via Nix won't work due to the lack of self-authentication.
if ! nix show-config | grep -q 'experimental-features.*ca-derivations'; then
  cat <<-EOF

ERROR: You must enable the "ca-derivations" in your Nix configuration to use
this project. See https://nixos.wiki/wiki/Ca-derivations for more information
and modify either:

  - your /etc/nixos/configuration.nix'
  - your /etc/nix/nix.conf'

EOF
  exit 1
fi

# Enable the nix-community direnv integration
if ! has nix_direnv_version || ! nix_direnv_version 2.2.0; then
  source "./buck/nix/etc/nix_direnvrc"
fi

# [tag:nix-direnv-watch-nix-files] Make sure we watch all files relevant to the
# "boostrap phase" here, so that changes appropriately cause the shell to be
# reloaded. Any extra nix files situated near the Flake should be added here.
nix_direnv_watch_file buck/nix/buck2/Cargo.lock buck/nix/buck2/default.nix
nix_direnv_watch_file buck/nix/toolchains/default.nix
nix_direnv_watch_file buck/nix/flake.nix buck/nix/flake.lock

# Enable the flake
use flake ./buck/nix --accept-flake-config

# Disable the log uploader in buck2, since it's not useful for us right now.
# XXX FIXME (aseipp): rethink this if we ever enable reapi support
export BUCK2_TEST_DISABLE_LOG_UPLOAD=true

# [tag:auto-watchman] In order to help keep track of files more accurately, we
# use Watchman, and we automatically start it if it's not already running, and
# the user has allowed it. This is a bit of a hack, but it helps keep the shell
# environment clean.
if [ "$(uname)" = "Darwin" ]; then
  # XXX FIXME (aseipp): macOS support
  echo "direnv: watchman: not enabling, because we're on macOS"
elif [ ! -f .use_watchman ] && [ -z "$CI_RUNNING" ]; then
  # XXX FIXME (aseipp): prompt about this file to the user
  echo "direnv: watchman: not enabled, because .use_watchman is missing, and we're not in a CI build"
else
  [ "$CI_RUNNING" = "true" ] && \
    echo "direnv: watchman: enabling, because we're running in a CI build"

  # XXX FIXME (aseipp): shouldn't require systemd on Linux, but in practice
  # systemd is the only option for multi-user Nix and the only thing supported by
  # upstream, so it is what it is.
  [ ! -d /run/systemd/system ] && \
    echo "direnv: watchman: ERROR: cannot enable, because you aren't using systemd" && \
    exit 1

  export WATCHMAN_SOCK=$HOME/.watchman-socket
  if ! systemctl --user is-active --quiet watchman; then
    echo "direnv: watchman: no service active; starting a transient watchman.service user unit..."
    systemd-run -q --user \
      -u watchman.service \
      --working-directory=$HOME \
      -p StateDirectory=watchman \
      -p StandardOutput=journal \
      -p Restart=on-failure \
      watchman --foreground \
        -u "$WATCHMAN_SOCK" \
        --logfile="$HOME/.config/watchman/log" \
        --statefile="$HOME/.config/watchman/state" \
        --pidfile="$HOME/.config/watchman/pid"

    echo "direnv: watchman: ok, see 'systemctl --user status watchman.service' for details"
  else
    echo "direnv: watchman: service is already active, continuing..."
  fi
fi