本页介绍了输出目录的要求和布局。
要求
输出目录布局的要求：
- 如果多个用户在同一盒子上构建，则不会发生冲突。
- 支持同时在多个工作区中构建。
- 支持在同一工作区中为多个目标配置构建。
- 不会与其他任何工具发生冲突。
- 易于访问。
- 易于清理，甚至可以选择性清理。
- 即使在用户更改为客户端目录时依赖符号链接，也不会产生歧义。
- 每个用户的构建状态都应位于一个目录下（“我想从所有客户端中清理所有 .o 文件。”）
当前布局
目前实现的解决方案：
- 必须从包含 WORKSPACE 文件（ “工作区目录”）的目录或其子目录调用 Bazel。否则，系统会报告错误。
- 在 Linux 上，输出根目录默认设置为
~/.cache/bazel；在 macOS 上，默认设置为/private/var/tmp；在 Windows 上，如果设置了%HOME%，则默认设置为该值，否则如果设置了%USERPROFILE%，则默认设置为该值，否则默认设置为调用SHGetKnownFolderPath()并设置FOLDERID_Profile标志的结果。 outputRoot如果设置了环境变量$TEST_TMPDIR（例如在 Bazel 本身的测试中），则该值会替换默认值。 - Bazel 用户的构建状态位于
outputRoot/_bazel_$USER下。 这称为“输出用户根目录”。 outputUserRoot - 在
outputUserRoot目录下，有一个install目录，其中包含一个installBase目录，其名称是 Bazel 安装清单的 MD5 哈希值。 - 在
outputUserRoot目录下，还会创建一个outputBase目录，其名称是工作区目录路径名称的 MD5 哈希值。因此，举例来说，如果 Bazel 在工作区目录/home/user/src/my-project（或符号链接到该目录的目录）中运行，则会创建一个名为/home/user/.cache/bazel/_bazel_user/7ffd56a6e4cb724ea575aba15733d113的输出基本目录。 - 您可以使用 Bazel 的
--output_base启动选项来替换默认的输出基本目录。例如，bazel --output_base=/tmp/bazel/output build x/y:z。 - 您还可以使用 Bazel 的
--output_user_root启动选项来替换默认的安装基本目录和输出基本目录。例如：bazel --output_user_root=/tmp/bazel build x/y:z。
“bazel-<workspace-name>”“bazel-out”“bazel-testlogs”和“bazel-bin”的符号链接放在工作区目录中；这些符号链接指向输出目录中特定于目标的目录中的某些目录。 这些符号链接仅为方便用户而设，Bazel 本身并不使用它们。此外，只有当工作区目录可写时，才会执行此操作。
布局图
目录的布局如下：
<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 $(BINDIR)
bazel-testlogs => <...testlogs> <== Convenience symlink to the test logs directory
/home/user/.cache/bazel/ <== Root for all Bazel output on a machine: outputRoot
_bazel_$USER/ <== Top level directory for a given user depends on the user name:
outputUserRoot
install/
fba9a2c87ee9589d72889caf082f1029/ <== Hash of the Bazel install manifest: installBase
_embedded_binaries/ <== Contains binaries and scripts unpacked from the data section of
the bazel executable on first run (such as helper scripts and the
main Java file BazelServer_deploy.jar)
7ffd56a6e4cb724ea575aba15733d113/ <== Hash of the client's workspace directory (such as
/home/some-user/src/my-project): outputBase
action_cache/ <== Action cache directory hierarchy
This contains the persistent record of the file
metadata (timestamps, and perhaps eventually also MD5
sums) used by the FilesystemValueChecker.
action_outs/ <== Action output directory. This contains a file with the
stdout/stderr for every action from the most recent
bazel run that produced output.
command.log <== A copy of the stdout/stderr output from the most
recent bazel command.
external/ <== The directory that remote repositories are
downloaded/symlinked into.
server/ <== The Bazel server puts all server-related files (such
as socket file, logs, etc) here.
jvm.out <== The debugging output for the server.
execroot/ <== The working directory for all actions. For special
cases such as sandboxing and remote execution, the
actions run in a directory that mimics execroot.
Implementation details, such as where the directories
are created, are intentionally hidden from the action.
All actions can access its inputs and outputs relative
to the execroot directory.
<workspace-name>/ <== Working tree for the Bazel build & root of symlink forest: execRoot
_bin/ <== Helper tools are linked from or copied to here.
bazel-out/ <== All actual output of the build is under here: outputPath
local_linux-fastbuild/ <== one subdirectory per unique target BuildConfiguration instance;
this is currently encoded
bin/ <== Bazel outputs binaries for target configuration here: $(BINDIR)
foo/bar/_objs/baz/ <== Object files for a cc_* rule named //foo/bar:baz
foo/bar/baz1.o <== Object files from source //foo/bar:baz1.cc
other_package/other.o <== Object files from source //other_package:other.cc
foo/bar/baz <== foo/bar/baz might be the artifact generated by a cc_binary named
//foo/bar:baz
foo/bar/baz.runfiles/ <== The runfiles symlink farm for the //foo/bar:baz executable.
MANIFEST
<workspace-name>/
...
genfiles/ <== Bazel puts generated source for the target configuration here:
$(GENDIR)
foo/bar.h such as foo/bar.h might be a headerfile generated by //foo:bargen
testlogs/ <== Bazel internal test runner puts test log files here
foo/bartest.log such as foo/bar.log might be an output of the //foo:bartest test with
foo/bartest.status foo/bartest.status containing exit status of the test (such as
PASSED or FAILED (Exit 1), etc)
include/ <== a tree with include symlinks, generated as needed. The
bazel-include symlinks point to here. This is used for
linkstamp stuff, etc.
host/ <== BuildConfiguration for build host (user's workstation), for
building prerequisite tools, that will be used in later stages
of the build (ex: Protocol Compiler)
<packages>/ <== Packages referenced in the build appear as if under a regular workspace
如需详细了解 *.runfiles 目录的布局，请参阅 RunfilesSupport 指向的位置。
bazel clean
bazel clean 会对 outputPath 和 action_cache 目录执行 rm -rf。它还会移除工作区符号链接。--expunge 选项将清理整个 outputBase。