本页将介绍输出目录的要求和布局。
要求
输出目录布局的要求：
- 即使有多个用户在同一个盒子上进行构建，也不会发生冲突。
- 支持同时在多个工作区中制作。
- 支持在同一工作区中针对多个目标配置进行构建。
- 不会与任何其他工具发生碰撞。
- 使用方便。
- 易于清洁，即使有选择性。
- 清晰明确，即使用户在切换到 客户名录。
- 每个用户的所有构建状态都应该放在一个目录下（“我想要 清除我所有客户端中的所有 .o 文件。”）
当前布局
目前实现的解决方案：
- 必须从包含 WORKSPACE 文件（ “workspace directory”）或其子目录来创建。如果存在以下情况，它将报告错误： 。
- 在 Linux 上，outputRoot 目录默认为
~/.cache/bazel。/private/var/tmp（在 macOS 上；在 Windows 上）默认为%HOME%（如果已设置）。 else%USERPROFILE%（如果已设置），否则返回调用 并设置了FOLDERID_Profile标志的SHGetKnownFolderPath()。如果 已设置环境变量$TEST_TMPDIR，如在 Bazel 本身的测试中一样。 则该值会替换默认值。 - Bazel 用户的构建状态位于
outputRoot/_bazel_$USER下方。 该目录称为 outputUserRoot 目录。 outputUserRoot目录下有一个install目录， 它是一个installBase目录，其名称是 Bazel 的 MD5 哈希 安装清单。- 在
outputUserRoot目录下，有一个outputBase目录 也会创建，其名称是工作区路径名的 MD5 哈希 目录。例如，如果 Bazel 正在工作区目录中运行/home/user/src/my-project（或以该目录的符号链接到的目录），则 将创建一个名为：/home/user/.cache/bazel/_bazel_user/7ffd56a6e4cb724ea575aba15733d113。 - 您可以使用 Bazel 的
--output_base启动选项来替换默认值 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 默认安装基础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”会放在工作区目录中这些符号链接指向某个 输出目录内目标专属目录中的目录。 这些符号链接只是为了方便用户，因为 Bazel 本身并不提供 使用它们。此外，仅当工作区目录可写入时，系统才会执行此操作。
布局图
目录布局如下：
<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
在 RunfilesSupport 指向的位置中详细介绍了 *.runfiles 目录的布局。
bazel clean
bazel clean 对 outputPath 和 action_cache 执行了 rm -rf 操作
目录。还会移除工作区符号链接。--expunge 选项
将清理整个 outputBase。