get-pants.sh

#!/usr/bin/env bash
# Copyright 2023 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

set -euo pipefail

COLOR_RED="\x1b[31m"
COLOR_GREEN="\x1b[32m"
COLOR_YELLOW="\x1b[33m"
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 warn() {
	(($# > 0)) && log "${COLOR_YELLOW}$*${COLOR_RESET}"
}

function check_cmd() {
	local cmd="$1"
	command -v "$cmd" >/dev/null || die "This script requires the ${cmd} binary to be on the PATH."
}

help_url="https://www.pantsbuild.org/docs/getting-help"

_GC=()

function gc() {
	if (($# > 0)); then
		check_cmd rm
		_GC+=("$@")
	else
		rm -rf "${_GC[@]}"
	fi
}

trap gc EXIT

check_cmd uname

function calculate_os() {
	local os

	os="$(uname -s)"
	if [[ "${os}" =~ [Ll]inux ]]; then
		echo linux
	elif [[ "${os}" =~ [Dd]arwin ]]; then
		echo macos
	elif [[ "${os}" =~ [Ww]in|[Mm][Ii][Nn][Gg] ]]; then
		# Powershell reports something like: Windows_NT
		# Git bash reports something like: MINGW64_NT-10.0-22621
		echo windows
	else
		die "Pants is not supported on this operating system (${os}). Please reach out to us at ${help_url} for help."
	fi
}

OS="$(calculate_os)"

check_cmd basename
if [[ "${OS}" == "windows" ]]; then
	check_cmd pwsh
else
	check_cmd curl
fi

function fetch() {
	local url="$1"
	local dest_dir="$2"

	local dest
	dest="${dest_dir}/$(basename "${url}")"

	if [[ "${OS}" == "windows" ]]; then
		pwsh -c "Invoke-WebRequest -OutFile $dest -Uri $url"
	else
		curl --proto '=https' --tlsv1.2 -sSfL -o "${dest}" "${url}"
	fi
}

if [[ "${OS}" == "macos" ]]; then
	check_cmd shasum
else
	check_cmd sha256sum
fi

function sha256() {
	if [[ "${OS}" == "macos" ]]; then
		shasum --algorithm 256 "$@"
	else
		sha256sum "$@"
	fi
}

check_cmd mktemp

function install_from_url() {
	local url="$1"
	local dest="$2"

	local workdir
	workdir="$(mktemp -d)"
	gc "${workdir}"

	fetch "${url}.sha256" "${workdir}"
	fetch "${url}" "${workdir}"
	(
		cd "${workdir}"
		sha256 -c --status ./*.sha256 ||
			die "Download from ${url} did not match the fingerprint at ${url}.sha256"
	)
	rm "${workdir}/"*.sha256
	if [[ "${OS}" == "macos" ]]; then
		mkdir -p "$(dirname "${dest}")"
		install -m 755 "${workdir}/"* "${dest}"
	else
		install -D -m 755 "${workdir}/"* "${dest}"
	fi
}

function calculate_arch() {
	local arch

	arch="$(uname -m)"
	if [[ "${arch}" =~ x86[_-]64 ]]; then
		echo x86_64
	elif [[ "${arch}" =~ arm64|aarch64 ]]; then
		echo aarch64
	else
		die "Pants is not supported for this chip architecture (${arch}). Please reach out to us at ${help_url} for help."
	fi
}

check_cmd cat

function usage() {
	cat <<EOF
Usage: $0

Installs the pants launcher binary.

You only need to run this once on a machine when you do not have "pants"
available to run yet.

The pants binary takes care of managing and running the underlying
Pants version configured in "pants.toml" in the surrounding Pants-using
project.

Once installed, if you want to update your "pants" launcher binary, use
"SCIE_BOOT=update pants" to get the latest release or
"SCIE_BOOT=update pants --help" to learn more options.

-h | --help: Print this help message.

-d | --bin-dir:
  The directory to install the scie-pants binary in, "~/bin" by default.

-b | --base-name:
  The name to use for the scie-pants binary, "pants" by default.

-V | --version:
  The version of the scie-pants binary to install, the latest version by default.
  The available versions can be seen at:
    https://github.com/pantsbuild/scie-pants/releases

EOF
}

bin_dir="${HOME}/bin"
base_name="pants"
version="latest/download"
while (($# > 0)); do
	case "$1" in
	--help | -h)
		usage
		exit 0
		;;
	--bin-dir | -d)
		bin_dir="$2"
		shift
		;;
	--base-name | -b)
		base_name="$2"
		shift
		;;
	--version | -V)
		version="download/v$2"
		shift
		;;
	*)
		usage
		die "Unexpected argument $1\n"
		;;
	esac
	shift
done

ARCH="$(calculate_arch)"
URL="https://github.com/pantsbuild/scie-pants/releases/${version}/scie-pants-${OS}-${ARCH}"
dest="${bin_dir}/${base_name}"

log "Downloading and installing the pants launcher ..."
install_from_url "${URL}" "${dest}"
green "Installed the pants launcher from ${URL} to ${dest}"
if ! command -v "${base_name}" >/dev/null; then
	warn "${dest} is not on the PATH."
	log "You'll either need to invoke ${dest} explicitly or else add ${bin_dir} to your shell's PATH."
fi

green "\nRunning \`pants\` in a Pants-enabled repo will use the version of Pants configured for that repo."
green "In a repo not yet Pants-enabled, it will prompt you to set up Pants for that repo."