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://www.pantsbuild.org/install.html
# ====================================================================

set -eou pipefail

PYTHON_BIN_NAME="${PYTHON:-unspecified}"

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

VENV_VERSION=${VENV_VERSION:-16.4.3}

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

COLOR_RED="\x1b[31m"
COLOR_GREEN="\x1b[32m"
COLOR_RESET="\x1b[0m"

function log() {
  echo -e "$@" 1>&2
}

function die() {
  (($# > 0)) && log "${COLOR_RED}$*${COLOR_RESET}"
  exit 1
}

function green() {
  (($# > 0)) && log "${COLOR_GREEN}$*${COLOR_RESET}"
}

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

function get_exe_path_or_die {
  exe="$1"
  if ! command -v "${exe}"; then
    die "Could not find ${exe}. Please ensure ${exe} is on your PATH."
  fi
}

function get_pants_ini_config_value {
  if [[ ! -f 'pants.ini' ]]; then
    return 0
  fi
  config_key="$1"
  valid_delimiters="[:=]"
  optional_space="[[:space:]]*"
  prefix="^${config_key}${optional_space}${valid_delimiters}${optional_space}"
  sed -ne "/${prefix}/ s#${prefix}##p" pants.ini
}

function get_python_major_minor_version {
  python_exe="$1"
  "$python_exe" <<EOF
import sys
major_minor_version = ''.join(str(version_num) for version_num in sys.version_info[0:2])
print(major_minor_version)
EOF
}

# The high-level flow:
# 1.) Resolve the Pants version from pants.ini or from the latest stable
#     release to PyPi, so that we know what to name the venv folder and which
#     Python versions we can use.
# 2.) Resolve the Python interpreter, first reading from the env var $PYTHON,
#     then reading from pants.ini, then determining the default based off of
#     which Python versions the Pants version supports.
# 3.) Check if the venv (virtual environment) already exists via a naming/path convention,
#     and create the venv if not found.
# 4.) Execute Pants with the resolved Python interpreter and venv.
#
# After that, Pants itself will handle making sure any requested plugins
# are installed and up to date.

function determine_pants_version {
  pants_version="$(get_pants_ini_config_value 'pants_version')"
  if [[ -n "${pants_version}" ]]; then
    echo "${pants_version}"
  else
    curl -sSL https://pypi.python.org/pypi/pantsbuild.pants/json |
      python -c "import json, sys; print(json.load(sys.stdin)['info']['version'])"
  fi
}

function determine_default_python_exe {
  pants_version="$1"
  pants_major_version="$(echo "${pants_version}" | cut -d '.' -f1)"
  pants_minor_version="$(echo "${pants_version}" | cut -d '.' -f2)"
  if [[ "${pants_major_version}" -eq 1 && "${pants_minor_version}" -le 14 ]]; then
    supported_python_versions=('2.7')
    supported_message='2.7'
  elif [[ "${pants_major_version}" -eq 1 && "${pants_minor_version}" -eq 15 ]]; then
    supported_python_versions=('3.6' '2.7')
    supported_message='2.7 or 3.6'
  elif [[ "${pants_major_version}" -eq 1 && "${pants_minor_version}" -eq 16 ]]; then
    supported_python_versions=('3.6' '3.7' '2.7')
    supported_message='2.7, 3.6, or 3.7'
  elif [[ "${pants_major_version}" -eq 1 && "${pants_minor_version}" -eq 17 ]]; then
    supported_python_versions=('3.6' '3.7' '3.8' '3.9')
    supported_message='3.6+'
  else
    supported_python_versions=('3.9' '3.8' '3.7' '3.6')
    supported_message='3.6+'
  fi
  for version in "${supported_python_versions[@]}"; do
    command -v "python${version}" && return 0
  done
  die "No valid Python interpreter found. For this Pants version, Pants requires Python ${supported_message}."
}

function determine_python_exe {
  pants_version="$1"
  if [[ "${PYTHON_BIN_NAME}" != 'unspecified' ]]; then
    python_bin_name="${PYTHON_BIN_NAME}"
  else
    interpreter_version="$(get_pants_ini_config_value 'pants_runtime_python_version')"
    if [[ -n "${interpreter_version}" ]]; then
      python_bin_name="python${interpreter_version}"
    else
      python_bin_name="$(determine_default_python_exe "${pants_version}")"
    fi
  fi
  get_exe_path_or_die "${python_bin_name}"
}

# 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_version="$1"
  python="$2"

  pants_requirement="pantsbuild.pants==${pants_version}"
  python_major_minor_version="$(get_python_major_minor_version "${python}")"
  target_folder_name="${pants_version}_py${python_major_minor_version}"

  if [[ ! -d "${PANTS_BOOTSTRAP}/${target_folder_name}" ]]; then
    (
      venv_path="$(bootstrap_venv)"
      staging_dir=$(tempdir "${PANTS_BOOTSTRAP}")
      "${python}" "${venv_path}/virtualenv.py" --no-download "${staging_dir}/install"
      "${staging_dir}/install/bin/pip" install -U pip
      "${staging_dir}/install/bin/pip" install "${pants_requirement}"
      ln -s "${staging_dir}/install" "${staging_dir}/${target_folder_name}"
      mv "${staging_dir}/${target_folder_name}" "${PANTS_BOOTSTRAP}/${target_folder_name}"
      green "New virtual environment successfully created at ${PANTS_BOOTSTRAP}/${target_folder_name}."
    ) 1>&2
  fi
  echo "${PANTS_BOOTSTRAP}/${target_folder_name}"
}

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


# 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" "$@"