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#!/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 $USE_BAZEL_VERSION to a version number
# (e.g. export USE_BAZEL_VERSION=1.0.0).
# 2. Add a .bazelversion file that contains a version number next to your
# WORKSPACE file.
# 3. Otherwise, the latest Bazel version will be used.
#
# This wrapper only recognizes Bazel versions installed next to itself, thus
# if you install this wrapper as /usr/bin/bazel, you'll have to install binaries
# for individual Bazel binaries as e.g. /usr/bin/bazel-1.0.0.
#
# In addition, if an executable called "tools/bazel" is found in the current
# workspace, this script will not directly execute Bazel, but instead store
# the path to the real Bazel executable in the environment variable BAZEL_REAL
# and then execute the "tools/bazel" wrapper script.
#
# In contrast to Bazelisk, this script does not download anything from the
# internet and instead relies on the local system to provide Bazel binaries.
function color() {
# Usage: color "31;5" "string"
# Some valid values for color:
# - 5 blink, 1 strong, 4 underlined
# - fg: 31 red, 32 green, 33 yellow, 34 blue, 35 purple, 36 cyan, 37 white
# - bg: 40 black, 41 red, 44 blue, 45 purple
printf '\033[%sm%s\033[0m\n' "$@"
}
# `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" ]]; 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/master/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}" "$@"
|
