Python virtual environment wrapper

py-venv-wrapper.sh

#!/usr/bin/env bash

# This script is a wrapper for creating and managing Python virtual environments.

# Usage:
#   py-venv-wrapper.sh <command>

# Run the script in the directory containing the requirements.txt file.
# The script will create a virtual environment in the ".venv" directory
# and execute the command within the virtual environment.

# The following environment variables can be set to customize the behavior of the script:
#   - REQUIREMENTS: The path to the requirements.txt file. Default: "$PWD/requirements.txt"
#   - VENV_DIR: The path to the virtual environment directory. Default: "$PWD/.venv"

set -e

REQUIREMENTS="${REQUIREMENTS:-"${PWD}/requirements.txt"}"
VENV_DIR="${VENV_DIR:-"${PWD}/.venv"}"

if [[ ! -f "${REQUIREMENTS}" ]]; then
  echo "ERROR: '${REQUIREMENTS}' not found." >&2
  exit 1
fi

UPDATE_VENV="false"

# Check if the requirements file has changed
if [[ ( ! -f "${VENV_DIR}/requirements.sha1" ) ]] || ! sha1sum --status --check "${VENV_DIR}/requirements.sha1"; then
  UPDATE_VENV="true"
fi

cleanup()
{
  rm -rf "${VENV_DIR}"
  echo "Cleaning up virtual environment." >&2
}

# If the virtual environment does not exist or the requirements file has changed,
# tear down the existing virtual environment and recreate it from scratch.
if [[ ! -d "${VENV_DIR}" || "${UPDATE_VENV}" == "true" ]]; then
  (
    trap cleanup ERR
    echo "Creating/updating virtual environment."
    rm -rf "${VENV_DIR}"
    python3 -m venv --copies "${VENV_DIR}"
    source "${VENV_DIR}/bin/activate"
    pip3 install -r "${REQUIREMENTS}"
    deactivate
    sha1sum "${REQUIREMENTS}" > "${VENV_DIR}/requirements.sha1"
    echo "Virtual environment created."
    echo
  ) >&2
fi

(
# Activate the virtual environment
source "${VENV_DIR}/bin/activate"

# Execute the command
"$@"
)