دستورات و گزینه ها

This flag lets you specify a binary that Bazel runs before each build. The program can report information about the status of the workspace, such as the current source control revision.

The flag's value must be a path to a native program. On Linux/macOS this may be any executable. On Windows this must be a native binary, typically an ".exe", ".bat", or a ".cmd" file.

The program should print zero or more key/value pairs to standard output, one entry on each line, then exit with zero (otherwise the build fails). The key names can be anything but they may only use upper case letters and underscores. The first space after the key name separates it from the value. The value is the rest of the line (including additional whitespaces). Neither the key nor the value may span multiple lines. Keys must not be duplicated.

Bazel partitions the keys into two buckets: "stable" and "volatile". (The names "stable" and "volatile" are a bit counter-intuitive, so don't think much about them.)

Bazel then writes the key-value pairs into two files:

• bazel-out/stable-status.txt contains all keys and values where the key's name starts with STABLE_
• bazel-out/volatile-status.txt contains the rest of the keys and their values

The contract is:

• "stable" keys' values should change rarely, if possible. If the contents of bazel-out/stable-status.txt change, Bazel invalidates the actions that depend on them. In other words, if a stable key's value changes, Bazel will rerun stamped actions. Therefore the stable status should not contain things like timestamps, because they change all the time, and would make Bazel rerun stamped actions with each build.

  Bazel always outputs the following stable keys:

  • BUILD_EMBED_LABEL : value of --embed_label
  • BUILD_HOST : the name of the host machine that Bazel is running on
  • BUILD_USER : the name of the user that Bazel is running as

• "volatile" keys' values may change often. Bazel expects them to change all the time, like timestamps do, and duly updates the bazel-out/volatile-status.txt file. In order to avoid rerunning stamped actions all the time though, Bazel pretends that the volatile file never changes . In other words, if the volatile status file is the only file whose contents has changed, Bazel will not invalidate actions that depend on it. If other inputs of the actions have changed, then Bazel reruns that action, and the action will see the updated volatile status, but just the volatile status changing alone will not invalidate the action.

  Bazel always outputs the following volatile keys:

  • BUILD_TIMESTAMP : time of the build in seconds since the Unix Epoch (the value of System.currentTimeMillis() divided by a thousand)

On Linux/macOS you can pass --workspace_status_command=/bin/true to disable retrieving workspace status, because true does nothing, successfully (exits with zero) and prints no output. On Windows you can pass the path of MSYS's true.exe for the same effect.

If the workspace status command fails (exits non-zero) for any reason, the build will fail.

Example program on Linux using Git:

#!/bin/bash
echo "CURRENT_TIME $(date +%s)"
echo "RANDOM_HASH $(cat /proc/sys/kernel/random/uuid)"
echo "STABLE_GIT_COMMIT $(git rev-parse HEAD)"
echo "STABLE_USER_NAME $USER"

Pass this program's path with --workspace_status_command , and the stable status file will include the STABLE lines and the volatile status file will include the rest of the lines.

$ bazel build --nobuild --starlark_cpu_profile=/tmp/pprof.gz my/project/...
$ pprof /tmp/pprof.gz
(pprof) top
Type: CPU
Time: Feb 6, 2020 at 12:06pm (PST)
Duration: 5.26s, Total samples = 3.34s (63.55%)
Showing nodes accounting for 3.34s, 100% of 3.34s total
      flat  flat%   sum%        cum   cum%
     1.86s 55.69% 55.69%      1.86s 55.69%  sort_source_files
     1.02s 30.54% 86.23%      1.02s 30.54%  expand_all_combinations
     0.44s 13.17% 99.40%      0.44s 13.17%  range
     0.02s   0.6%   100%      3.34s   100%  sorted
         0     0%   100%      1.38s 41.32%  my/project/main/BUILD
         0     0%   100%      1.96s 58.68%  my/project/library.bzl
         0     0%   100%      3.34s   100%  main

        --run_under=/usr/bin/strace
        --run_under='/usr/bin/strace -c'
        --run_under=/usr/bin/valgrind
        --run_under='/usr/bin/valgrind --quiet --num-callers=20'

  % bazel run java/myapp:myapp -- --arg1 --arg2
  Welcome to Bazel
  INFO: Loading package: java/myapp
  INFO: Loading package: foo/bar
  INFO: Loading complete.  Analyzing...
  INFO: Found 1 target...
  ...
  Target //java/myapp:myapp up-to-date:
    bazel-bin/java/myapp:myapp
  INFO: Elapsed time: 0.638s, Critical Path: 0.34s

  INFO: Running command line: bazel-bin/java/myapp:myapp --arg1 --arg2
  Hello there
  $EXEC_ROOT/java/myapp/myapp
  --arg1
  --arg2

  % bazel clean --expunge

  bazel query --output location 'kind(genrule, deps(kind(".*_test rule", foo/bar/pebl/...)))'

% bazel info server_pid
1285

  % bazel info --show_make_env -c opt COMPILATION_MODE
  opt

% bazel info --cpu=piii bazel-bin
/var/tmp/_bazel_johndoe/fbd0e8a34f61ce5d491e3da69d959fe6/execroot/io_bazel/bazel-out/piii-opt/bin
% bazel info --cpu=k8 bazel-bin
/var/tmp/_bazel_johndoe/fbd0e8a34f61ce5d491e3da69d959fe6/execroot/io_bazel/bazel-out/k8-opt/bin

% bazel mobile-install --adb_arg=-s --adb_arg=deadbeef

adb -s deadbeef install ...

    % bazel --host_jvm_args=-javaagent:$BAZEL/third_party/allocation_instrumenter/java-allocation-instrumenter-3.3.0.jar \
    --host_jvm_args=-DRULE_MEMORY_TRACKER=1 \
    build --nobuild <targets>

    # Dump rules
    % bazel --host_jvm_args=-javaagent:$BAZEL/third_party/allocation_instrumenter/java-allocation-instrumenter-3.3.0.jar \
    --host_jvm_args=-DRULE_MEMORY_TRACKER=1 \
    dump --rules

    # Dump Starlark heap and analyze it with pprof
    % bazel --host_jvm_args=-javaagent:$BAZEL/third_party/allocation_instrumenter/java-allocation-instrumenter-3.3.0.jar \
    --host_jvm_args=-DRULE_MEMORY_TRACKER=1 \
    dump --skylark_memory=$HOME/prof.gz
    % pprof -flame $HOME/prof.gz

  % bazel canonicalize-flags -- --config=any_name --test_tag_filters="-lint"
  --config=any_name
  --test_tag_filters=-lint

 OUTPUT_BASE=/var/tmp/google/_bazel_johndoe/custom_output_base
% bazel --output_base ${OUTPUT_BASE}1 build //foo  &  bazel --output_base ${OUTPUT_BASE}2 build //bar

  % bazel --server_javabase=/usr/local/buildtools/java/jdk11 build //foo

  % bazel --host_jvm_args="-Xss256K" build //foo