如何在Bazel构建的项目中使用libcap-dev Debian依赖包？

方案一：直接复用系统已安装的libcap-dev #

如果你的构建环境已经通过包管理器（如apt install libcap-dev）安装了libcap-dev，无需额外操作，直接在BUILD文件中定义链接系统库的cc_library即可：

1. 在项目BUILD文件中添加：

cc_library(
    name = "libcap",
    srcs = [],
    hdrs = [],
    linkopts = ["-lcap"],
    includes = ["/usr/include"],  # 系统默认安装路径，自定义安装需调整
    visibility = ["//visibility:public"],
)

2. 在你的目标二进制或库中依赖该规则：

cc_binary(
    name = "your_app",
    srcs = ["main.cpp"],
    deps = [":libcap"],
)

这是最轻便的方案，完全复用系统预安装的库，不需要重新构建。

方案二：用rules_foreign_cc自动安装系统依赖 #

如果构建环境允许使用包管理器（有安装权限），可以用rules_foreign_cc的apt_get规则在构建阶段自动安装libcap-dev，避免手动提前安装：

1. 先在WORKSPACE文件中引入rules_foreign_cc：

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rules_foreign_cc",
    sha256 = "a1b2c3d4e5f6...",  # 替换为对应版本的校验值
    url = "https://github.com/bazelbuild/rules_foreign_cc/releases/download/0.9.0/rules_foreign_cc-0.9.0.tar.gz",
)

load("@rules_foreign_cc//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")
rules_foreign_cc_dependencies()

2. 在BUILD文件中定义安装和依赖规则：

load("@rules_foreign_cc//foreign_cc:defs.bzl", "apt_get")

apt_get(
    name = "install_libcap",
    packages = ["libcap-dev"],
    # 可选：指定版本，比如"libcap-dev=1:2.44-1"
)

cc_library(
    name = "libcap",
    srcs = [],
    hdrs = [],
    linkopts = ["-lcap"],
    includes = ["/usr/include"],
    visibility = ["//visibility:public"],
    deps = [":install_libcap"],
)

注意：这种方式需要构建环境有apt的安装权限（比如在容器或拥有sudo权限的环境中执行Bazel构建）。

方案三：手动引入预构建库（无安装权限时） #

如果无法在构建环境安装libcap-dev，可以手动下载libcap的预构建头文件和库文件，放入项目目录后配置Bazel使用：

1. 下载libcap的头文件（包含sys/cap.h等）和库文件（libcap.so），放在项目的third_party/libcap目录下，结构示例：

third_party/libcap/
├── include/
│   └── sys/
│       └── cap.h
└── lib/
    └── libcap.so

2. 在third_party/libcap/BUILD中添加规则：

cc_library(
    name = "libcap",
    srcs = ["lib/libcap.so"],
    hdrs = glob(["include/**/*.h"]),
    includes = ["include"],
    visibility = ["//visibility:public"],
)

3. 在项目BUILD文件中依赖该库：

cc_binary(
    name = "your_app",
    srcs = ["main.cpp"],
    deps = ["//third_party/libcap:libcap"],
)

备选方案：从源码构建libcap（别无他法时） #

如果以上方案都不可行，只能从源码构建libcap，用rules_foreign_cc的configure_make规则自动处理：

1. 在WORKSPACE中引入libcap源码包：

http_archive(
    name = "libcap_source",
    sha256 = "abcdef123456...",  # 替换为对应版本的校验值
    url = "https://www.kernel.org/pub/linux/libs/security/linux-privs/libcap2/libcap-2.44.tar.gz",
)

2. 在BUILD文件中添加构建规则：

load("@rules_foreign_cc//foreign_cc:defs.bzl", "configure_make")

configure_make(
    name = "libcap_build",
    lib_source = "@libcap_source//:all_files",
    configure_options = ["--prefix=$(GENDIR)/install"],
    install_prefix = "install",
    out_include_dir = "include",
    out_lib_dir = "lib",
)

cc_library(
    name = "libcap",
    srcs = ["@libcap_build//:lib/libcap.so"],
    hdrs = glob(["@libcap_build//:include/**/*.h"]),
    includes = ["@libcap_build//:include"],
    visibility = ["//visibility:public"],
)

这样Bazel会自动完成源码编译、安装，并生成可供项目依赖的cc_library。

内容的提问来源于stack exchange，提问作者Antoun