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框中进行构建，则不会发生冲突。
- 支持同时在多个工作区中进行构建。
- 支持在同一工作区中为多个目标配置进行构建。
- 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。
- 明确无误，即使在用户更改为 客户端目录时依赖符号链接也是如此。
- 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
当前实现的解决方案：
- 必须从包含代码库边界文件的目录或其 子目录中调用 Bazel。换句话说，必须从 代码库内部调用 Bazel。否则，系统会报告错误 。
- 在 Linux 上，outputRoot 目录默认为
${XDG_CACHE_HOME}/bazel（如果未设置XDG_CACHE_HOME环境变量，则为~/.cache/bazel）；在 macOS 上，默认为/private/var/tmp；在 Windows 上，如果设置了%HOME%，则默认为该值，否则如果设置了%USERPROFILE%，则默认为该值，否则默认为调用SHGetKnownFolderPath()并设置FOLDERID_Profile标志的结果。如果设置了 环境变量$TEST_TMPDIR（例如在测试 Bazel 本身时）， 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 outputUserRoot 目录。 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 根路径名称的 MD5 哈希值。因此，例如，如果 Bazel 在工作区根目录/home/user/src/my-project中运行（或在符号链接到该目录的目录中运行），则会创建名为 的输出基本目录：/home/user/.cache/bazel/_bazel_user/7ffd56a6e4cb724ea575aba15733d113。您还可以在工作区根目录中运行echo -n $(pwd) | md5sum以获取 MD5。 - 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，因为 Bazel 本身并不 使用它们。此外，只有当工作区根目录可写时，才会执行此操作。
布局图
目录的布局如下：
<workspace-name>/ <== The workspace root
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 root (such as
/home/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.
Every action can access its inputs and outputs relative
to the execroot directory.
_main/ <== 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
_main/
...
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
RunfilesSupport 指向的位置更详细地介绍了 *.runfiles 目录的布局。
bazel clean
bazel clean 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。