pants

#!/usr/bin/env bash
# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

# =============================== NOTE ===============================
# This pants bootstrap script comes from the pantsbuild/setup
# project and is intended to be checked into your code repository so
# that any developer can check out your code and be building it with
# pants with no prior setup needed.
#
# You can learn more here: https://pantsbuild.github.io/setup
# ====================================================================

set -eou pipefail

PYTHON=${PYTHON:-$(which python2.7)}

PANTS_HOME="${PANTS_HOME:-${XDG_CACHE_HOME:-$HOME/.cache}/pants/setup}"
PANTS_BOOTSTRAP="${PANTS_HOME}/bootstrap-$(uname -s)-$(uname -m)"

VENV_VERSION=${VENV_VERSION:-16.0.0}

# This requirement is installed before pantsbuild.pants to hack around
# interpreters that have newer setuptools already installed, effectively
# re-installing an older setuptools and pinning low to a version known to be 
# ingestable by both pants and pex for all reasonable versions of pants.
# See:
#   https://github.com/pantsbuild/pants/issues/3948
#   https://github.com/pantsbuild/setup/issues/14
#   https://github.com/pantsbuild/setup/issues/19
SETUPTOOLS_REQUIREMENT="setuptools==5.4.1"

VENV_PACKAGE=virtualenv-${VENV_VERSION}
VENV_TARBALL=${VENV_PACKAGE}.tar.gz

# The high-level flow:
# 1.) Grab pants version from pants.ini or default to latest.
# 2.) Check for a venv via a naming/path convention and execute if found.
# 3.) Otherwise create venv and re-exec self.
#
# After that pants itself will handle making sure any requested plugins
# are installed and up to date.

function tempdir {
  mktemp -d "$1"/pants.XXXXXX
}

# TODO(John Sirois): GC race loser tmp dirs leftover from bootstrap_XXX
# functions.  Any tmp dir w/o a symlink pointing to it can go.

function bootstrap_venv {
  if [[ ! -d "${PANTS_BOOTSTRAP}/${VENV_PACKAGE}" ]]
  then
    (
      mkdir -p "${PANTS_BOOTSTRAP}"
      staging_dir=$(tempdir "${PANTS_BOOTSTRAP}")
      cd "${staging_dir}"
      curl -LO https://pypi.io/packages/source/v/virtualenv/${VENV_TARBALL}
      tar -xzf ${VENV_TARBALL}
      ln -s "${staging_dir}/${VENV_PACKAGE}" "${staging_dir}/latest"
      mv "${staging_dir}/latest" "${PANTS_BOOTSTRAP}/${VENV_PACKAGE}"
    ) 1>&2
  fi
  echo "${PANTS_BOOTSTRAP}/${VENV_PACKAGE}"
}

function bootstrap_pants {
  pants_requirement="pantsbuild.pants"
  pants_version=$(
    grep -E "^[[:space:]]*pants_version" pants.ini 2>/dev/null | \
      cut -f2 -d: | tr -d " "
  )
  if [[ -n "${pants_version}" ]]
  then
    pants_requirement="${pants_requirement}==${pants_version}"
  else
    pants_version="unspecified"
  fi

  if [[ ! -d "${PANTS_BOOTSTRAP}/${pants_version}" ]]
  then
    (
      # NB: We setup the virtualenv with no setuptools to ensure our
      # ${SETUPTOOLS_REQUIREMENT} wins.
      venv_path="$(bootstrap_venv)"
      staging_dir=$(tempdir "${PANTS_BOOTSTRAP}")
      "${PYTHON}" "${venv_path}/virtualenv.py" --no-setuptools --no-download \
        "${staging_dir}/install"
      "${staging_dir}/install/bin/pip" install -U pip
      "${staging_dir}/install/bin/pip" install "${SETUPTOOLS_REQUIREMENT}"
      "${staging_dir}/install/bin/pip" install "${pants_requirement}"
      ln -s "${staging_dir}/install" "${staging_dir}/${pants_version}"
      mv "${staging_dir}/${pants_version}" "${PANTS_BOOTSTRAP}/${pants_version}"
    ) 1>&2
  fi
  echo "${PANTS_BOOTSTRAP}/${pants_version}"
}

# Ensure we operate from the context of the ./pants buildroot.
cd "$(cd "$(dirname ${BASH_SOURCE[0]})" && pwd -P)"
pants_dir=$(bootstrap_pants)


# We set the env var no_proxy to '*', to work around an issue with urllib using non
# async-signal-safe syscalls after we fork a process that has already spawned threads.
#
# See https://blog.phusion.nl/2017/10/13/why-ruby-app-servers-break-on-macos-high-sierra-and-what-can-be-done-about-it/
export no_proxy=*

exec "${pants_dir}/bin/python" "${pants_dir}/bin/pants" "$@"