Use non-Bazel Libraries in Bazel Project

2022-11-10ProgrammingBazel

One may want to use external libraries that Bazel does not manage when using Bazel.¹

cc_binary(
  name = "hello-world",
  srcs = ["main.cpp"],
  deps = [
    # external libraries that are not managed by bazel
  ],
)

To use local files in Bazel, one can use new_local_repository. ²

new_local_repository is a function that can be used in WORKSPACE files, which adds a BUILD file virtually and make a local directory Bazel project. One can specify the BUILD file by the option build_file orbuild_file_content. For example, if one wants to use OpenSSL in its local storage, a sample code with build_file is the following:

# WORKSPACE.bazel
new_local_repository(
  name = "openssl",
  path = "/opt/homebrew/Cellar/openssl@3/3.0.5",
  build_file = "openssl.BUILD",
)

# openssl.BUILD
cc_library(
  name = "lib",
  hdrs = glob(["include/**/*.h"]),
  srcs = glob(["lib/*.dylib"]),
  strip_include_prefix = "include",
  visibility = ["//visibility:public"],
)

A sample code with build_file_content is the following:

# WORKSPACE.bazel
new_local_repository(
  name = "openssl",
  path = "/opt/homebrew/Cellar/openssl@3/3.0.5",
  build_file_content = """
cc_library(
  name = "lib",
  hdrs = glob(["include/**/*.h"]),
  srcs = glob(["lib/*.dylib"]),
  strip_include_prefix = "include",
  visibility = ["//visibility:public"],
)""",
)

In the latter case, one needs to set proper indents, or it will not be recognized as a correct BUILD file.

1. Q. As one can know from the official document, why is this page needed? → A. Some people have unusual creativity.
2. To use remote files managed by Git build_file or build_file_content in git_repository can be used the same way as this page. (ref)