Bazel Intro - HackMD

<style> .reveal *:not(pre) > code:not([class]) { background: #3e3d3280; border-radius: 5px; } .reveal pre > code:not([class]) { background: #272822; } code.inline { background: #3e3d3280; border-radius: 20px; padding-top: 0.5%; padding-right: 2%; padding-bottom: 0.5%; padding-left: 2%; } code.bazel { background: #272822; } pre.graphviz { background: none; box-shadow: none; } .subtext { font-size:0.6em; font-style:italic; } </style>                    slide: https://hackmd.io/p/S1frKIJo4#/ <div style="font-size: medium; font-style: italic;"> Danny Chang </div> ---- ## Who am I ? 張嘉軒 Danny Chang _Danny.Chang@dlinkcorp.com_ --- <style> .reveal section img.thissec { margin: 0px; background: none; border: none; box-shadow: none; } </style> # Bazel A open-source build and test tool. <br> _makefile_    <img src="https://maven.apache.org/images/maven-logo-black-on-white.png" alt="Maven" height="86" width="340" class="thissec" >    <img src="https://upload.wikimedia.org/wikipedia/en/e/ed/Gradle_Logo.png" alt="Gradle" height="148" width="428" class="thissec" > ---- # Why Bazel ? ---- - High-level build language - Fast and Reliable - Multi-Platform - Scalable - Extensible --- # Walkthrough --- # C++ ---- ## Stage 1：Simple Build ---- ## Stage 1：File structure ------ ``` examples └── cpp-tutorial └── stage1 <---- Current Working Directory ├── main │ ├── BUILD │ └── hello-world.cc └── WORKSPACE ``` https://github.com/bazelbuild/examples/ ---- ## <code class="inline">WORKSPACE</code> ----- A blank file that defines a project's root. ---- ## <code class="inline">BUILD</code> ----- Tells Bazel how to build. A `BUILD` file defines a _package_ . ---- _cpp-tutorial/stage1/main/BUILD_ ```bazel cc_binary( name = "hello-world", srcs = ["hello-world.cc"], ) ``` ---- <style> span.subtext { font-size:0.6em; font-style:italic; } </style> ### <code class="inline">cc_binary</code> is a <span style="color:red;">_target_</span> of type <span style="color:red;">_**Rule**_</span> ----- Defines the actions perform on inputs. <span class="subtext">cc_binary、cc_import、cc_library、cc_proto_library、fdo_prefetch_hints、fdo_profile、cc_test、cc_toolchain、cc_toolchain_suite</span> ---- ### Dig into <code class="inline">BUILD</code> ``` cc_binary( # <------------ Rule name = "hello-world", # <---- Target name srcs = ["hello-world.cc"], # <---- File to be processed ) ``` ---- ### Build the project ```sh $ bazel build //main:hello-world ``` <code style="font-size:0.8em; background: #3e3d3280; border-radius: 5px;">//main:hello-world</code> <span style="font-size:0.8em;">is a</span>  <i style="color:red; font-size:0.8em;"> label </i> <span style="font-size:0.8em;">.</span>  ---- ### Build the project ```sh $ bazel build //main:hello-world ``` Build output  ```sh Starting local Bazel server and connecting to it... INFO: Analysed target //main:hello-world (9 packages loaded, 63 targets configured). INFO: Found 1 target... Target //main:hello-world up-to-date: bazel-bin/main/hello-world INFO: Elapsed time: 7.009s, Critical Path: 0.58s INFO: 2 processes: 2 linux-sandbox. INFO: Build completed successfully, 4 total actions ```  ---- ### Run ```sh $ bazel-bin/main/hello-world ``` Output  ``` Hello world Sun Apr 28 16:49:15 2019 ```  ---- ## Stage 2：Multiple Targets ---- ## Stage 2：File structure ------ ``` examples └── cpp-tutorial └── stage2 <---- Current Working Directory ├── main │ ├── BUILD │ ├── hello-world.cc │ ├── hello-greet.cc │ └── hello-greet.h └── WORKSPACE ``` ---- _cpp-tutorial/stage2/main/BUILD_ ```bazel cc_library( # <------------ Target 1 name = "hello-greet", # <---- Target name srcs = ["hello-greet.cc"], # <---- File to be processed hdrs = ["hello-greet.h"], # <---- Header file ) cc_binary( # <------------ Target 2 name = "hello-world", srcs = ["hello-world.cc"], deps = [ # <------------- Dependent libraries ":hello-greet", ], ) ``` ---- <style> .reveal section dd.lowertext { font-size: 0.6em !important; } dd > code { } </style> ## Labels ``` //path/to/package:target-name ``` `//` means workspace directory. <dl> <dt style="font-size: 0.7em;">skipping：</dt> <dd class="lowertext">- Targets within same package, skip path.</li> <dd class="lowertext">- Targets within same <code>BUILD</code> file, skip <code>//</code>. </dt> </dl> ```bazel deps = [ <------------- Dependent libraries ":hello-greet", ], ```  --- # Java ---- ## Stage 1：Simple Build ---- ## Stage 1：File structure ------ ``` java-tutorial <---- Current Working Directory ├── BUILD <---- First Package ├── src │ └── main │ └── java │ └── com │ └── example │ ├── cmdline │ │ ├── BUILD <---- Second Package │ │ └── Runner.java │ ├── Greeting.java │ └── ProjectRunner.java <---- main └── WORKSPACE ``` ---- _java-tutorial/BUILD_ ```bazel java_binary( # <------------ Java Rule name = "ProjectRunner", srcs = glob(["src/main/java/com/example/*.java"]), ) ``` `glob` is a helper function to pass a set of files. ---- #### Build ```sh $ bazel build //:ProjectRunner ``` #### Build Output  ```sh INFO: Found 1 target... Target //:ProjectRunner up-to-date: bazel-bin/ProjectRunner.jar bazel-bin/ProjectRunner INFO: Elapsed time: 0.568s, Critical Path: 0.28s INFO: 1 process: 1 worker. INFO: Build completed successfully, 5 total actions ```  #### Run  ```sh $ bazel-bin/ProjectRunner // Output: Hi! ```  ---- #### Dependency Graph ----- ```graphviz digraph mygraph { graph [color="#232323" bgcolor="#232323"] node [fillcolor=white style=filled shape=box] edge [color=white] "//:ProjectRunner" "//:ProjectRunner" -> "//:src/main/java/com/example/Greeting.java\n//:src/main/java/com/example/ProjectRunner.java" "//:src/main/java/com/example/Greeting.java\n//:src/main/java/com/example/ProjectRunner.java" } ``` <span class="subtext" style="text-align:left;"> pros：Sufficient for small projects <br>cons：Slow incremental builds and lack of extensibility. </span> ---- ## Stage 2：Refined Build ---- _java-tutorial/BUILD_ ```bazel java_binary( name = "ProjectRunner", srcs = ["src/main/java/com/example/ProjectRunner.java"], main_class = "com.example.ProjectRunner", deps = [":greeter"], ) java_library( name = "greeter", srcs = ["src/main/java/com/example/Greeting.java"], ) ``` ---- #### Dependency Graph ----- ```graphviz digraph mygraph { graph [color="#232323" bgcolor="#232323"] node [fillcolor=white style=filled shape=box] edge [color=white] "//:ProjectRunner" "//:ProjectRunner" -> "//:greeter" "//:ProjectRunner" -> "//:src/main/java/com/example/ProjectRunner.java" "//:greeter" "//:greeter" -> "//:src/main/java/com/example/Greeting.java" "//:src/main/java/com/example/Greeting.java" "//:src/main/java/com/example/ProjectRunner.java" } ``` ---- ## Stage 3：File structure ------ ``` java-tutorial <---- Current Working Directory ├── BUILD <---- First Package ├── src │ └── main │ └── java │ └── com │ └── example │ ├── cmdline │ │ ├── BUILD <---- Second Package │ │ └── Runner.java <---- main │ ├── Greeting.java │ └── ProjectRunner.java └── WORKSPACE ``` ---- <span style="font-size:0.7em;">_java-tutorial/src/main/java/com/example/cmdline/BUILD_</span> ```bazel java_binary( name = "runner", srcs = ["Runner.java"], main_class = "com.example.cmdline.Runner", # <---- Class of entry point deps = ["//:greeter"] ) ``` <span style="font-size:0.8em;">`main_class` specifies the class contains main.</span> ---- _java-tutorial/BUILD_ ```bazel java_library ( name = "greeter", srcs = ["src/main/java/com/example/Greeting.java"], visibility = ["//src/main/java/com/example/cmdline:__pkg__"], ) ``` <span style="font-size:0.8em;">'Cause targets are only accessible within same `BUILD`, we need to add `visibility` attribute.</span> ---- #### Dependency Graph ----- ```graphviz digraph mygraph { graph [color="#232323" bgcolor="#232323"] node [fillcolor=white style=filled shape=box] edge [color=white] "//src/main/java/com/example/cmdline:runner" "//src/main/java/com/example/cmdline:runner" -> "//src/main/java/com/example/cmdline:Runner.java" "//src/main/java/com/example/cmdline:runner" -> "//:greeter" "//:greeter" "//:greeter" -> "//:src/main/java/com/example/Greeting.java" "//:src/main/java/com/example/Greeting.java" "//src/main/java/com/example/cmdline:Runner.java" } ``` ---- #### Build ```sh $ bazel build //src/main/java/com/example/cmdline:runner ``` #### Build Output  ```sh INFO: Found 1 target... Target //src/main/java/com/example/cmdline:runner up-to-date: bazel-bin/src/main/java/com/example/cmdline/runner.jar bazel-bin/src/main/java/com/example/cmdline/runner INFO: Elapsed time: 0.217s, Critical Path: 0.00s INFO: 0 processes. INFO: Build completed successfully, 1 total action ```  #### Run  ```sh $ bazel-bin/src/main/java/com/example/cmdline/runner // Output: Hi! ```  --- ### Step into Bazel output directory ```sh $ ll total 40 drwxrwxr-x ./ drwxrwxr-x ../ lrwxrwxrwx bazel-bin -> /home/chdontu18/.cache/bazel/_bazel_chdontu18/613107f5ff7df42ab30d11644f0cbc5d/execroot/__main__/bazel-out/k8-fastbuild/bin/ lrwxrwxrwx bazel-genfiles -> /home/chdontu18/.cache/bazel/_bazel_chdontu18/613107f5ff7df42ab30d11644f0cbc5d/execroot/__main__/bazel-out/k8-fastbuild/genfiles/ lrwxrwxrwx bazel-java-tutorial -> /home/chdontu18/.cache/bazel/_bazel_chdontu18/613107f5ff7df42ab30d11644f0cbc5d/execroot/__main__/ lrwxrwxrwx bazel-out -> /home/chdontu18/.cache/bazel/_bazel_chdontu18/613107f5ff7df42ab30d11644f0cbc5d/execroot/__main__/bazel-out/ lrwxrwxrwx bazel-testlogs -> /home/chdontu18/.cache/bazel/_bazel_chdontu18/613107f5ff7df42ab30d11644f0cbc5d/execroot/__main__/bazel-out/k8-fastbuild/testlogs/ -rw-rw-r-- BUILD drwxrwxr-x src/ -rw-rw-r-- WORKSPACE ``` ---- ### Bazel output directory layout ``` - <workspace-name>/ <== The workspace directory - bazel-my-project => <...my-project> <== Symlink to execRoot - bazel-out => <...bin> <== Convenience symlink to outputPath - bazel-bin => <...bin> <== Convenience symlink to most recent written bin dir $(BINDIR) - bazel-genfiles => <...genfiles> <== Convenience symlink to most recent written genfiles dir $(GENDIR) ``` --- # End