Bazel use tutorial to

bazel Use the tutorial

bazel All the code of is in the current project , Every project is a WORKSPACE. Every WORKSPACE There are multiple under package（ contain BUILD The folder of files is called package）,BUILD Inside are multiple targets, The same package Internal targets Mutually visible by default , Different package Between targets Visibility of requires manual definition , Can be in each package Of BUILD The top of the file declares targets Default visibility to other packages .

One 、 install bazel

Reference resources ：Installing Bazel on Ubuntu 

sudo apt install curl
curl https://bazel.build/bazel-release.pub.gpg | sudo apt-key add -
echo "deb [arch=amd64] https://storage.googleapis.com/bazel-apt stable jdk1.8" | sudo tee /etc/apt/sources.list.d/bazel.list
sudo apt-get update 
sudo apt-get install bazel #  install bazel
sudo apt-get install --only-upgrade bazel #  upgrade bazel To the latest version 

see bazel edition

bazel version

BUILD For building documents "#" Start with a single line comment  

Two 、 Compile operation

Reference resources ：Command-Line Reference

bazel clean

bazel clean #  External dependencies will not be deleted 
bazel clean --expunge #  Will delete external dependencies 
bazel clean --expunge --async
bazel build

bazel build :<exe name> #  stay BUILD Where package Execute under directory , Compile the specified target
bazel build :all  #  Compile the package All under target
bazel build ...  #  Compile the package All under target
bazel build <//path/to/package>:<exe name> #  stay workspace Execute in any directory under ,“//” Express workspace In the directory 
bazel build :<exe name> --compilation_mode=dbg # debug mode
bazel build :<exe name> -c dbg # debug mode
bazel build :<exe name> --keep_going #  See all the mistakes 
bazel build :<exe name> --config=<asan/tsan/msan> # Build the project with sanitizers by adding the --config=<asan/tsan/msan> build flag to select AddressSanitizer (asan), ThreadSanitizer (tsan) or MemorySanitizer (msan) accordingly.
bazel build :<exe name> --config local_first
bazel run

bazel run :<target name>
bazel run -- :<target name>

There is no need to execute build, In execution run,run Will automatically first build Re execution

bazel test

bazel test:<target name>

working principle

Loading and target Relevant BUILD file
analysis inputs and dependencies, Generate action graph
perform graph, Produce outputs
action graph： bazel Rely on this graph to track file changes , And whether you need to recompile , And it can also provide users with dependency diagrams between codes .

bazel query 'deps(//<path_to_package>:<target_name>)' #  see target Dependence 
bazel query "somepath(//<path_to_package>:<target1_name>,//<path_to_package>:<target2_name>)"

3、 ... and 、WORKSPACE file

Reference resources ：Working with external dependencies

WORKSPACE The file is mainly named workspace And declare external dependencies , This includes the acquisition methods and acquisition methods of external dependencies .WORKSPACE File tell Bazel How to get other engineering sources , then package Medium BUILD The document can be based on WORKSPACE The outside of target Name dependency .WORKSPACE Files allow users to rely on the goals of other file systems or downloaded from the Internet . In addition to bazel build It can automatically obtain external dependencies , You can also use bazel fetch To obtain a .Bazel Will cache external dependencies , And only in WORKSPACE Download and update again after the file is changed .WORKSPACE The syntax and BUILD The documents are consistent , However, some specific built-in rule. All external dependencies will be downloaded to a soft connection directory named . The specific content can be obtained through the command line ：

ls $(bazel info output_base)/external

There are three main types of external dependencies ：

1、 Depend on others Bazel engineering

According to this Bazel The location of the project is different , Call different built-in rule To obtain a ：

local_repository： Local
git_repository：git Warehouse
http_archive： Download Online

2、 Rely on other non Bazel engineering

There is another case that another project is not Bazel engineering , Then you need another way to add dependent references

new_local_repository： Local
new_git_repository：git Warehouse
new_http_archive： Download Online

3、 Rely on external packages

Maven Warehouse ：Use the rule maven_jar (and optionally the rule maven_server) to download a jar from a Maven repository and make it available as a Java dependency.

Workspace Rules

Reference resources ：C / C++ Rules

bind

bind(name, actual, compatible_with, deprecation, distribs, features, licenses, restricted_to, tags, testonly, visibility)

to target Life alias , It is not recommended to use

git_repository

git_repository(name, commit, init_submodules, remote, sha256, tag)
This has many restrictions and is not recommended , use http_archive Instead of making it more robust and safe .

http_archive

http_archive(name, sha256, strip_prefix, type, url, urls)
Download a compressed format Bazel Warehouse , And extract it , Then bind and use . This Rule There is an attribute strip_prefix, Used to eliminate prefix directories .

give an example ：

(1) glog / gflags

Directory structure

├── WORKSPACE
├── BUILD
└── main.cc

WORKSPACE

workspace(name = "bazel_test")
 
load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 
git_repository(
    name = "com_github_gflags_gflags",
    commit = "f7388c6655e699f777a5a74a3c9880b9cfaabe59",
    remote = "https://github.com/gflags/gflags.git",
)
 
git_repository(
    name = "glog",
    commit = "0a2e5931bd5ff22fd3bf8999eb8ce776f159cda6",
    remote = "https://github.com/google/glog.git",
)
BUILD

cc_binary(
    name = "bazel_test",
    srcs = ["main.cc"],
    deps = [
      "@com_github_gflags_gflags//:gflags",
      "@glog",
    ],
)

main.cc

#include <glog/logging.h>
#include <gflags/gflags.h>
 
DEFINE_string(name, "alan", "your name");
 
int main(int argc, char *argv[]) {
    google::InitGoogleLogging(argv[0]);
    FLAGS_logtostderr = 1;
    FLAGS_colorlogtostderr = 1;
    gflags::ParseCommandLineFlags(&argc, &argv, true);
 
    LOG(INFO) << "hello " << FLAGS_name;
 
    return 0;
}

perform

bazel run -- :bazel_test --name alan

(2) gtest

Directory structure

├── WORKSPACE
├── gtest.BUILD
├── main.cc
└── BUILD
WORKSPACE

workspace(name = "bazel_test")
 
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
http_archive(
    name = "gtest",
    url = "https://github.com/google/googletest/archive/release-1.7.0.zip",
    sha256 = "b58cb7547a28b2c718d1e38aee18a3659c9e3ff52440297e965f5edffe34b6d0",
    build_file = "@//:gtest.BUILD",
    strip_prefix = "googletest-release-1.7.0",
)

gtest.BUILD

cc_library(
    name = "main",
    srcs = glob(
        ["src/*.cc"],
        exclude = ["src/gtest-all.cc"]
    ),
    hdrs = glob([
        "include/**/*.h",
        "src/*.h"
    ]),
    copts = ["-Iexternal/gtest/include"],
    linkopts = ["-pthread"],
    visibility = ["//visibility:public"],
)

BUILD

cc_test(
    name = "bazel_test",
    srcs = ["main.cc"],
    copts = ["-Iexternal/gtest/include"],
    deps = [
        "@gtest//:main",
    ],
)

 main.cc

#include "gtest/gtest.h"
 
int abs(int x) {
  return x >= 0? x : -x;
}
 
TEST(BazelTest, AbsTest) {
  EXPECT_EQ(abs(-1), 1);
}

perform

bazel test :bazel_test

Reference resources ：Introduction to Bazel: Common C++ Build Use Cases

(3) proto

Directory structure

├── WORKSPACE
├── BUILD
├── main.cc
└── foo.proto

WORKSPACE

workspace(name = "bazel_test")
 
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
http_archive(
    name = "rules_proto",
    sha256 = "602e7161d9195e50246177e7c55b2f39950a9cf7366f74ed5f22fd45750cd208",
    strip_prefix = "rules_proto-97d8af4dc474595af3900dd85cb3a29ad28cc313",
    urls = [
        "https://mirror.bazel.build/github.com/bazelbuild/rules_proto/archive/97d8af4dc474595af3900dd85cb3a29ad28cc313.tar.gz",
        "https://github.com/bazelbuild/rules_proto/archive/97d8af4dc474595af3900dd85cb3a29ad28cc313.tar.gz",
    ],
)
load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
rules_proto_dependencies()
rules_proto_toolchains()
BUILD

#load("@rules_cc//cc:defs.bzl", "cc_proto_library")
#load("@rules_proto//proto:defs.bzl", "proto_library")
 
cc_binary(
    name = "bazel_test",
    srcs = ["main.cc"],
    deps = [":foo_cc_proto"],
)
 
proto_library(
    name = "foo_proto",
    srcs = [
        "foo.proto",
    ],
)
 
cc_proto_library(
    name = "foo_cc_proto",
    deps = [
        ":foo_proto",
    ],
)

 main.cc

#include "foo.pb.h"
 
int main(int argc, char *argv[]) {
    foo::Bar bar;
    bar.set_id(10);
    std::cout << "id: " << bar.id() << std::endl;
    return 0;
}

foo.proto 

syntax = "proto3";
 
package foo;
 
message Bar {
  int32 id = 1;
}

perform

bazel run :bazel_test

Reference resources ：GitHub - bazelbuild/rules_proto: Protocol buffer rules for Bazel 

(4) eigen

Directory structure

├── WORKSPACE
├── BUILD
└── main.cc
WORKSPACE

workspace(name = "bazel_test")
 
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
http_archive(
    name = "com_github_eigen_eigen",
    sha256 = "dd254beb0bafc695d0f62ae1a222ff85b52dbaa3a16f76e781dce22d0d20a4a6",
    strip_prefix = "eigen-eigen-5a0156e40feb",
    urls = [
        "http://bitbucket.org/eigen/eigen/get/3.3.4.tar.bz2",
    ],
    build_file_content =
"""
cc_library(
    name = 'eigen',
    srcs = [],
    includes = ['.'],
    hdrs = glob(['Eigen/**']),
    visibility = ['//visibility:public'],
)
"""
)
BUILD

cc_binary(
    name = "bazel_test",
    srcs = ["main.cc"],
    deps = [
        "@com_github_eigen_eigen//:eigen",
    ],
)

main.cc

#include <iostream>
#include <Eigen/Dense>
 
int main(int argc, char *argv[])
{
    Eigen::Matrix3d m = Eigen::Matrix3d::Identity();
    std::cout << m << std::endl;
    return 0;
}

perform

bazel run :bazel_test

(5) ceres ( rely on gflags、glog、eigen、benchmark)

Directory structure

├── WORKSPACE
├── BUILD
└── main.cc
WORKSPACE

workspace(name = "bazel_test")
 
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
# External dependency: Google Flags; has Bazel build already.
http_archive(
    name = "com_github_gflags_gflags",
    sha256 = "6e16c8bc91b1310a44f3965e616383dbda48f83e8c1eaa2370a215057b00cabe",
    strip_prefix = "gflags-77592648e3f3be87d6c7123eb81cbad75f9aef5a",
    urls = [
        "https://mirror.bazel.build/github.com/gflags/gflags/archive/77592648e3f3be87d6c7123eb81cbad75f9aef5a.tar.gz",
        "https://github.com/gflags/gflags/archive/77592648e3f3be87d6c7123eb81cbad75f9aef5a.tar.gz",
    ],
)
# External dependency: Google Log; has Bazel build already.
http_archive(
    name = "com_github_google_glog",
    sha256 = "7083af285bed3995b5dc2c982f7de39bced9f0e6fd78d631f3285490922a0c3d",
    strip_prefix = "glog-3106945d8d3322e5cbd5658d482c9ffed2d892c0",
    urls = [
        "https://github.com/drigz/glog/archive/3106945d8d3322e5cbd5658d482c9ffed2d892c0.tar.gz",
    ],
)
# External dependency: Eigen; has no Bazel build.
http_archive(
    name = "com_github_eigen_eigen",
    sha256 = "dd254beb0bafc695d0f62ae1a222ff85b52dbaa3a16f76e781dce22d0d20a4a6",
    strip_prefix = "eigen-eigen-5a0156e40feb",
    urls = [
        "http://bitbucket.org/eigen/eigen/get/3.3.4.tar.bz2",
    ],
    build_file_content =
"""
# TODO(keir): Replace this with a better version, like from TensorFlow.
# See https://github.com/ceres-solver/ceres-solver/issues/337.
cc_library(
    name = 'eigen',
    srcs = [],
    includes = ['.'],
    hdrs = glob(['Eigen/**']),
    visibility = ['//visibility:public'],
)
"""
)
# External dependency: Google Benchmark; has no Bazel build.
http_archive(
    name = "com_github_google_benchmark",
    urls = ["https://github.com/google/benchmark/archive/56f52ee228783547f544d9ac4a533574b9010e3f.zip"],
    sha256 = "8c1c6e90cd320b07504fabb86400f390faff2e599183ebd9396908817968ae79",
    strip_prefix = "benchmark-56f52ee228783547f544d9ac4a533574b9010e3f",
    build_file_content =
"""
cc_library(
    name = "benchmark",
    srcs = glob([
        "src/*.h",
        "src/*.cc",
    ]),
    hdrs = glob(["include/benchmark/*.h"]),
    copts = [
        "-DHAVE_STD_REGEX",
    ],
    includes = [
        "include",
    ],
    visibility = ["//visibility:public"],
)
"""
)
 
local_repository(
    name = "ceres",
    path = "/home/alan/3rdparty/ceres-solver-1.14.0",
)

BUILD

cc_binary(
    name = "bazel_test",
    srcs = ["main.cc"],
    deps = [
      "@ceres",
    ],
)

main.cc

#include <iostream>
#include <Eigen/Dense>
 
int main(int argc, char *argv[])
{
    Eigen::Matrix3d m = Eigen::Matrix3d::Identity();
    std::cout << m << std::endl;
    return 0;
}

perform

bazel run :bazel_test
Reference resources ：

Non-linear Least Squares — Ceres Solver

https://ceres-solver.googlesource.com/ceres-solver/+/master/WORKSPACE

(6) opencv

Link local compilation and installation opencv library

git clone https://github.com/opencv/opencv.git
cd opencv/
mkdir build install
cd build
cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/home/alan/3rdparty/opencv/install ..
make install

Directory structure

├── WORKSPACE
├── opencv.BUILD
├── main.cc
└── BUILD
WORKSPACE

workspace(name = "bazel_test")
 
new_local_repository(
    name = "opencv",
    path = "/home/alan/3rdparty/opencv/install",
    build_file = "opencv.BUILD",
)
opencv.BUILD

cc_library(
    name = "opencv",
    srcs = glob(["lib/*.so*"]),
    hdrs = glob(["include/**/*.hpp"]),
    includes = ["include"],
    visibility = ["//visibility:public"], 
    linkstatic = 1,
)
BUILD

cc_binary(
    name = "bazel_test",
    srcs = ["main.cc"],
    deps = [
      "@opencv//:opencv",
    ],
)
 main.cc

#include <opencv2/opencv.hpp>
 
int main(int argc, char *argv[]) {
    cv::Mat img = cv::imread("/home/alan/1.jpg");
    std::cout << "Resolution: " << img.rows << " x " << img.cols << std::endl;
    return 0;
}
perform

bazel run :bazel_test
Reference resources ：Building OpenCV code using Bazel

tf_cc_binary： Object file Compilation Rules , As a binary executable .name Must be unique ,srcs Specifies the source file ,linkopts Link rules specified ,deps The dependent file is specified

cc_library： Library file Compilation Rules ,name Specifies the file name after compiling as a library file ,srcs and hdrs Specify source and header files ,deps Specify other files to rely on

tf_cc_test： Test file rules

package： Common methods , The defined value will apply to each of the following children rule in .default_visibility Specifies the default visibility rule for this package . Can only be seen by other package call .

licenses： Common methods , default license

load： Common methods , load .bzl file

filegroup： Common methods , For multiple compilation targets target Specify a name ,glob Is a help function , Specifies which files in the directory will include, Which will exclude.visibility It specifies target The visibility of , That is, what can be package call
 

name Attribute to name rules ,

deps Attribute to describe the dependencies between rules . Use colons to separate package names from rule names . If the rule that a rule depends on is in another directory , Just use "//" start , If it's in the same directory , You can ignore the package name and start with a colon .

linkopts Link rules specified