scripts/packages/bazel.sh - bazel - Git at Google

 #!/bin/bash

 # Copyright 2019 The Bazel Authors. All rights reserved.
 #
 # 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.

 set -eu

 # This is a script which can be installed as your "bazel" binary instead of the
 # real Bazel binary. When called, it tries to determine and run the correct
 # Bazel version for a given project and forwards all arguments to it.
 #
 # You can specify which Bazel version to use using these methods:
 # 1. Set $USE_BAZEL_VERSION to a version number
 #    (e.g. export USE_BAZEL_VERSION=1.0.0).
 # 2. Add a .bazelversion file that contains a version number next to your
 #    WORKSPACE[.bazel] file.
 # 3. Otherwise, the latest Bazel version will be used.
 #
 # This wrapper only recognizes Bazel versions installed next to itself, thus
 # if you install this wrapper as /usr/bin/bazel, you'll have to install binaries
 # for individual Bazel binaries as e.g. /usr/bin/bazel-1.0.0.
 #
 # In addition, if an executable called "tools/bazel" is found in the current
 # workspace, this script will not directly execute Bazel, but instead store
 # the path to the real Bazel executable in the environment variable BAZEL_REAL
 # and then execute the "tools/bazel" wrapper script.
 #
 # In contrast to Bazelisk, this script does not download anything from the
 # internet and instead relies on the local system to provide Bazel binaries.

 function color() {
       # Usage: color "31;5" "string"
       # Some valid values for color:
       # - 5 blink, 1 strong, 4 underlined
       # - fg: 31 red,  32 green, 33 yellow, 34 blue, 35 purple, 36 cyan, 37 white
       # - bg: 40 black, 41 red, 44 blue, 45 purple
       printf '\033[%sm%s\033[0m\n' "$@"
 }

 # `readlink -f` that works on OSX too.
 function get_realpath() {
     if [ "$(uname -s)" == "Darwin" ]; then
         local queue="$1"
         if [[ "${queue}" != /* ]] ; then
             # Make sure we start with an absolute path.
             queue="${PWD}/${queue}"
         fi
         local current=""
         while [ -n "${queue}" ]; do
             # Removing a trailing /.
             queue="${queue#/}"
             # Pull the first path segment off of queue.
             local segment="${queue%%/*}"
             # If this is the last segment.
             if [[ "${queue}" != */* ]] ; then
                 segment="${queue}"
                 queue=""
             else
                 # Remove that first segment.
                 queue="${queue#*/}"
             fi
             local link="${current}/${segment}"
             if [ -h "${link}" ] ; then
                 link="$(readlink "${link}")"
                 queue="${link}/${queue}"
                 if [[ "${link}" == /* ]] ; then
                     current=""
                 fi
             else
                 current="${link}"
             fi
         done

         echo "${current}"
     else
         readlink -f "$1"
     fi
 }

 function get_workspace_root() {
   workspace_dir="${PWD}"
   while [[ "${workspace_dir}" != / ]]; do
     if [[ -e "${workspace_dir}/WORKSPACE" || -e "${workspace_dir}/WORKSPACE.bazel" ]]; then
       readonly workspace_dir
       return
     fi
     workspace_dir="$(dirname "${workspace_dir}")"
   done
   readonly workspace_dir=""
 }

 get_workspace_root

 readonly wrapper_dir="$(dirname "$(get_realpath "${BASH_SOURCE[0]}")")"
 readonly os_arch_suffix="$(uname -s | tr '[:upper:]' '[:lower:]')-$(uname -m)"

 function get_bazel_version() {
   bazel_version=""

   if [[ -n ${USE_BAZEL_VERSION:-} ]]; then
     reason="specified in \$USE_BAZEL_VERSION"
     bazel_version="${USE_BAZEL_VERSION}"
   elif [[ -e "${workspace_dir}/.bazelversion" ]]; then
     reason="specified in ${workspace_dir}/.bazelversion"
     # The "read" can fail if the .bazelversion file does not contain a final
     # newline character. It will still correctly assign the read data to the
     # variable. Of course it can also fail due to real I/O errors. Because we do
     # validation of the read data later, we can just ignore the error here.
     # Alternatives like 'bazel_version=$(head -1 ...)' are not better either,
     # because bash does not care about the exit code of processes used in
     # command substitution.
     read -r bazel_version < "${workspace_dir}/.bazelversion" || true
   fi

   # If we read an empty string or the magic word "latest" from .bazelversion or
   # $USE_BAZEL_VERSION, then we should use the latest available stable version.
   # This mimics the behavior of Bazelisk.
   if [[ -z $bazel_version || $bazel_version == "latest" ]]; then
     if [[ -x "${wrapper_dir}/bazel-real" ]]; then
       reason="${reason:-"automatically selected bazel-real"}"
       bazel_version="real"
     else
       # Find the latest Bazel version installed on the system.
       reason="${reason:-"automatically selected latest available version"}"
       bazel_version="$(basename "$(find -H "${wrapper_dir}" -maxdepth 1 -name 'bazel-[0-9]*-${os_arch_suffix}' -type f | sort -V | tail -n 1)")"
       if [[ -z $bazel_version ]]; then
         bazel_version="$(basename "$(find -H "${wrapper_dir}" -maxdepth 1 -name 'bazel-[0-9]*' -type f | sort -V | tail -n 1)")"
       fi
       # Remove the "bazel-" prefix from the file name.
       bazel_version="${bazel_version#"bazel-"}"
     fi
   fi

   readonly reason
   readonly bazel_version
 }

 get_bazel_version

 BAZEL_REAL="${wrapper_dir}/bazel-${bazel_version}-${os_arch_suffix}"

 # Try without the architecture suffix.
 if [[ ! -x ${BAZEL_REAL} ]]; then
   BAZEL_REAL="${wrapper_dir}/bazel-${bazel_version}"
 fi

 # Last try: Maybe `bazel-real` is actually the requested correct version?
 readonly bazel_real_path="${wrapper_dir}/bazel-real"
 if [[ ! -x ${BAZEL_REAL} && -x ${bazel_real_path} ]]; then
   # Note that "bazel --version" is very fast and doesn't start the Bazel server,
   # as opposed to "bazel version".
   readonly bazel_real_version="$("${bazel_real_path}" --version | grep '^bazel ' | cut -d' ' -f2)"
   if [[ $bazel_real_version == $bazel_version ]]; then
     BAZEL_REAL="${bazel_real_path}"
   fi
 fi

 # If the repository contains a checked-in executable called tools/bazel, we
 # assume that they know what they're doing and have their own way of versioning
 # Bazel. Thus, we don't have to print our helpful messages or error out in case
 # we couldn't find a binary.
 readonly wrapper="${workspace_dir}/tools/bazel"
 if [[ -x "$wrapper" && -f "$wrapper" ]]; then
   export BAZEL_REAL
   exec -a "$0" "${wrapper}" "$@"
 fi

 if [[ -z $bazel_version ]]; then
   color "31" "ERROR: No installed Bazel version found, cannot continue."
   (echo ""
   echo "Bazel binaries have to be installed in ${wrapper_dir}, but none were found.") 2>&1
   exit 1
 fi

 if [[ ! -x $BAZEL_REAL ]]; then
   color "31" "ERROR: The project you're trying to build requires Bazel ${bazel_version} (${reason}), but it wasn't found in ${wrapper_dir}."

   long_binary_name="bazel-${bazel_version}-${os_arch_suffix}"

   if [[ -x $(command -v apt-get) && $wrapper_dir == "/usr/bin" ]]; then
     (echo ""
     echo "You can install the required Bazel version via apt:"
     echo "  sudo apt update && sudo apt install bazel-${bazel_version}"
     echo ""
     echo "If this doesn't work, check Bazel's installation instructions for help:"
     echo "  https://docs.bazel.build/versions/main/install-ubuntu.html") 2>&1
   else
     (echo ""
     echo "Bazel binaries for all official releases can be downloaded from here:"
     echo "  https://github.com/bazelbuild/bazel/releases") 2>&1

     if [[ -x $(command -v curl) && -w $wrapper_dir ]]; then
       (echo ""
       echo "You can download the required version directly using this command:"
       echo "  (cd \"${wrapper_dir}\" && curl -fLO https://releases.bazel.build/${bazel_version}/release/${long_binary_name} && chmod +x ${long_binary_name})") 2>&1
     elif [[ -x $(command -v wget) && -w $wrapper_dir ]]; then
       (echo ""
       echo "You can download the required version directly using this command:"
       echo "  (cd \"${wrapper_dir}\" && wget https://releases.bazel.build/${bazel_version}/release/${long_binary_name} && chmod +x ${long_binary_name})") 2>&1
     else
       (echo ""
       echo "Please put the downloaded Bazel binary into this location:"
       echo "  ${wrapper_dir}/${long_binary_name}") 2>&1
     fi
   fi
   exit 1
 fi

 exec -a "$0" "${BAZEL_REAL}" "$@"
	#!/bin/bash

	# Copyright 2019 The Bazel Authors. All rights reserved.
	#
	# 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.

	set -eu

	# This is a script which can be installed as your "bazel" binary instead of the
	# real Bazel binary. When called, it tries to determine and run the correct
	# Bazel version for a given project and forwards all arguments to it.
	#
	# You can specify which Bazel version to use using these methods:
	# 1. Set $USE_BAZEL_VERSION to a version number
	# (e.g. export USE_BAZEL_VERSION=1.0.0).
	# 2. Add a .bazelversion file that contains a version number next to your
	# WORKSPACE[.bazel] file.
	# 3. Otherwise, the latest Bazel version will be used.
	#
	# This wrapper only recognizes Bazel versions installed next to itself, thus
	# if you install this wrapper as /usr/bin/bazel, you'll have to install binaries
	# for individual Bazel binaries as e.g. /usr/bin/bazel-1.0.0.
	#
	# In addition, if an executable called "tools/bazel" is found in the current
	# workspace, this script will not directly execute Bazel, but instead store
	# the path to the real Bazel executable in the environment variable BAZEL_REAL
	# and then execute the "tools/bazel" wrapper script.
	#
	# In contrast to Bazelisk, this script does not download anything from the
	# internet and instead relies on the local system to provide Bazel binaries.

	function color() {
	# Usage: color "31;5" "string"
	# Some valid values for color:
	# - 5 blink, 1 strong, 4 underlined
	# - fg: 31 red, 32 green, 33 yellow, 34 blue, 35 purple, 36 cyan, 37 white
	# - bg: 40 black, 41 red, 44 blue, 45 purple
	printf '\033[%sm%s\033[0m\n' "$@"
	}

	# `readlink -f` that works on OSX too.
	function get_realpath() {
	if [ "$(uname -s)" == "Darwin" ]; then
	local queue="$1"
	if [[ "${queue}" != /* ]] ; then
	# Make sure we start with an absolute path.
	queue="${PWD}/${queue}"
	fi
	local current=""
	while [ -n "${queue}" ]; do
	# Removing a trailing /.
	queue="${queue#/}"
	# Pull the first path segment off of queue.
	local segment="${queue%%/*}"
	# If this is the last segment.
	if [[ "${queue}" != / ]] ; then
	segment="${queue}"
	queue=""
	else
	# Remove that first segment.
	queue="${queue#*/}"
	fi
	local link="${current}/${segment}"
	if [ -h "${link}" ] ; then
	link="$(readlink "${link}")"
	queue="${link}/${queue}"
	if [[ "${link}" == /* ]] ; then
	current=""
	fi
	else
	current="${link}"
	fi
	done

	echo "${current}"
	else
	readlink -f "$1"
	fi
	}

	function get_workspace_root() {
	workspace_dir="${PWD}"
	while [[ "${workspace_dir}" != / ]]; do
	if [[ -e "${workspace_dir}/WORKSPACE" \|\| -e "${workspace_dir}/WORKSPACE.bazel" ]]; then
	readonly workspace_dir
	return
	fi
	workspace_dir="$(dirname "${workspace_dir}")"
	done
	readonly workspace_dir=""
	}

	get_workspace_root

	readonly wrapper_dir="$(dirname "$(get_realpath "${BASH_SOURCE[0]}")")"
	readonly os_arch_suffix="$(uname -s \| tr '[:upper:]' '[:lower:]')-$(uname -m)"

	function get_bazel_version() {
	bazel_version=""

	if [[ -n ${USE_BAZEL_VERSION:-} ]]; then
	reason="specified in \$USE_BAZEL_VERSION"
	bazel_version="${USE_BAZEL_VERSION}"
	elif [[ -e "${workspace_dir}/.bazelversion" ]]; then
	reason="specified in ${workspace_dir}/.bazelversion"
	# The "read" can fail if the .bazelversion file does not contain a final
	# newline character. It will still correctly assign the read data to the
	# variable. Of course it can also fail due to real I/O errors. Because we do
	# validation of the read data later, we can just ignore the error here.
	# Alternatives like 'bazel_version=$(head -1 ...)' are not better either,
	# because bash does not care about the exit code of processes used in
	# command substitution.
	read -r bazel_version < "${workspace_dir}/.bazelversion" \|\| true
	fi

	# If we read an empty string or the magic word "latest" from .bazelversion or
	# $USE_BAZEL_VERSION, then we should use the latest available stable version.
	# This mimics the behavior of Bazelisk.
	if [[ -z $bazel_version \|\| $bazel_version == "latest" ]]; then
	if [[ -x "${wrapper_dir}/bazel-real" ]]; then
	reason="${reason:-"automatically selected bazel-real"}"
	bazel_version="real"
	else
	# Find the latest Bazel version installed on the system.
	reason="${reason:-"automatically selected latest available version"}"
	bazel_version="$(basename "$(find -H "${wrapper_dir}" -maxdepth 1 -name 'bazel-[0-9]*-${os_arch_suffix}' -type f \| sort -V \| tail -n 1)")"
	if [[ -z $bazel_version ]]; then
	bazel_version="$(basename "$(find -H "${wrapper_dir}" -maxdepth 1 -name 'bazel-[0-9]*' -type f \| sort -V \| tail -n 1)")"
	fi
	# Remove the "bazel-" prefix from the file name.
	bazel_version="${bazel_version#"bazel-"}"
	fi
	fi

	readonly reason
	readonly bazel_version
	}

	get_bazel_version

	BAZEL_REAL="${wrapper_dir}/bazel-${bazel_version}-${os_arch_suffix}"

	# Try without the architecture suffix.
	if [[ ! -x ${BAZEL_REAL} ]]; then
	BAZEL_REAL="${wrapper_dir}/bazel-${bazel_version}"
	fi

	# Last try: Maybe `bazel-real` is actually the requested correct version?
	readonly bazel_real_path="${wrapper_dir}/bazel-real"
	if [[ ! -x ${BAZEL_REAL} && -x ${bazel_real_path} ]]; then
	# Note that "bazel --version" is very fast and doesn't start the Bazel server,
	# as opposed to "bazel version".
	readonly bazel_real_version="$("${bazel_real_path}" --version \| grep '^bazel ' \| cut -d' ' -f2)"
	if [[ $bazel_real_version == $bazel_version ]]; then
	BAZEL_REAL="${bazel_real_path}"
	fi
	fi

	# If the repository contains a checked-in executable called tools/bazel, we
	# assume that they know what they're doing and have their own way of versioning
	# Bazel. Thus, we don't have to print our helpful messages or error out in case
	# we couldn't find a binary.
	readonly wrapper="${workspace_dir}/tools/bazel"
	if [[ -x "$wrapper" && -f "$wrapper" ]]; then
	export BAZEL_REAL
	exec -a "$0" "${wrapper}" "$@"
	fi

	if [[ -z $bazel_version ]]; then
	color "31" "ERROR: No installed Bazel version found, cannot continue."
	(echo ""
	echo "Bazel binaries have to be installed in ${wrapper_dir}, but none were found.") 2>&1
	exit 1
	fi

	if [[ ! -x $BAZEL_REAL ]]; then
	color "31" "ERROR: The project you're trying to build requires Bazel ${bazel_version} (${reason}), but it wasn't found in ${wrapper_dir}."

	long_binary_name="bazel-${bazel_version}-${os_arch_suffix}"

	if [[ -x $(command -v apt-get) && $wrapper_dir == "/usr/bin" ]]; then
	(echo ""
	echo "You can install the required Bazel version via apt:"
	echo " sudo apt update && sudo apt install bazel-${bazel_version}"
	echo ""
	echo "If this doesn't work, check Bazel's installation instructions for help:"
	echo " https://docs.bazel.build/versions/main/install-ubuntu.html") 2>&1
	else
	(echo ""
	echo "Bazel binaries for all official releases can be downloaded from here:"
	echo " https://github.com/bazelbuild/bazel/releases") 2>&1

	if [[ -x $(command -v curl) && -w $wrapper_dir ]]; then
	(echo ""
	echo "You can download the required version directly using this command:"
	echo " (cd \"${wrapper_dir}\" && curl -fLO https://releases.bazel.build/${bazel_version}/release/${long_binary_name} && chmod +x ${long_binary_name})") 2>&1
	elif [[ -x $(command -v wget) && -w $wrapper_dir ]]; then
	(echo ""
	echo "You can download the required version directly using this command:"
	echo " (cd \"${wrapper_dir}\" && wget https://releases.bazel.build/${bazel_version}/release/${long_binary_name} && chmod +x ${long_binary_name})") 2>&1
	else
	(echo ""
	echo "Please put the downloaded Bazel binary into this location:"
	echo " ${wrapper_dir}/${long_binary_name}") 2>&1
	fi
	fi
	exit 1
	fi

	exec -a "$0" "${BAZEL_REAL}" "$@"