pants

#!/usr/bin/env bash
#
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the 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
# ====================================================================

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

PANTS_HOME="${PANTS_HOME:-${HOME}/.cache/pants/setup}"
PANTS_BOOTSTRAP="${PANTS_HOME}/bootstrap"

VENV_VERSION=13.1.0

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 ${staging_dir} && \
      curl -O https://pypi.python.org/packages/source/v/virtualenv/${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
    (
      venv_path="$(bootstrap_venv)" && \
      staging_dir=$(tempdir "${PANTS_BOOTSTRAP}") && \
      "${PYTHON}" "${venv_path}/virtualenv.py" "${staging_dir}/install" && \
      source "${staging_dir}/install/bin/activate" && \
      pip install "${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}"
}

pants_dir=$(bootstrap_pants) && \
exec "${pants_dir}/bin/pants" "$@"