bin/cmake_aux/create_virtualenv.sh

#!/bin/bash
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#
# Create a python virtualenv. When system python is 3.6 or higher,
# we can just use the built-in venv module to create the virtualenv.
# If system python is older or the built-in venv module fails, then
# this falls back to impala-virtualenv, which uses python2 to
# initialize a virtualenv using the specified interpeter.
#
# This takes two arguments, which is the interpreter to use and the
# destination directory for the virtualenv:
# create_virtualenv.sh pythonX venv_dir

set -euo pipefail

PYTHON_EXE=$1
VENV_DIR=$2

IS_PY36_OR_HIGHER=$(${PYTHON_EXE} -c "import sys; print(\
  'true' if sys.version_info.major >= 3 and sys.version_info.minor >= 6 else 'false')")

# If using Python >= 3.6, try to use the builtin venv package.
if $IS_PY36_OR_HIGHER ; then
  if ${PYTHON_EXE} -m venv ${VENV_DIR} ; then
    # Success
    exit 0
  fi
  # Failure
  echo "WARNING: Tried to create virtualenv with Python3's venv module and failed."
  echo "Falling back to old impala-virtualenv path..."
  # Remove the directory that Python3 venv created, so impala-virtualenv can start
  # from a clean slate.
  rm -rf ${VENV_DIR}
fi

# Fall back to using the old impala-virtualenv method
impala-virtualenv --python ${PYTHON_EXE} ${VENV_DIR}