Workspace Rules

Workspace rules are used to pull in external dependencies, typically source code located outside the main repository.

Note: besides the native workspace rules, Bazel also embeds various Starlark workspace rules, in particular those to deal with git repositories or archives hosted on the web.

bind

bind(name, actual, compatible_with, deprecation, distribs, features, licenses, restricted_to, tags, target_compatible_with, testonly, visibility)

Warning: use of bind() is not recommended. See "Consider removing bind" for a long discussion of its issues and alternatives. In particular, consider the use of repo_mapping repository attributes.

Warning: select() cannot be used in bind(). See the Configurable Attributes FAQ for details.

Gives a target an alias in the //external package.

The //external package is not a "normal" package: there is no external/ directory, so it can be thought of as a "virtual package" that contains all bound targets.

Examples

To give a target an alias, bind it in the WORKSPACE file. For example, suppose there is a java_library target called //third_party/javacc-v2. This can be aliased by adding the following to the WORKSPACE file:

bind(
    name = "javacc-latest",
    actual = "//third_party/javacc-v2",
)

Now targets can depend on //external:javacc-latest instead of //third_party/javacc-v2. If javacc-v3 is released, the bind rule can be updated and all of the BUILD files depending on //external:javacc-latest will now depend on javacc-v3 without needing to be edited.

Bind can also be used to make targets in external repositories available to your workspace. For example, if there is a remote repository named @my-ssl imported in the WORKSPACE file and it has a cc_library target //src:openssl-lib, you can create an alias for this target using bind:

bind(
    name = "openssl",
    actual = "@my-ssl//src:openssl-lib",
)

Then, in a BUILD file in your workspace, the bound target can be used as follows:

cc_library(
    name = "sign-in",
    srcs = ["sign_in.cc"],
    hdrs = ["sign_in.h"],
    deps = ["//external:openssl"],
)

Within sign_in.cc and sign_in.h, the header files exposed by //external:openssl can be referred to using their path relative to their repository root. For example, if the rule definition for @my-ssl//src:openssl-lib looks like this:

cc_library(
    name = "openssl-lib",
    srcs = ["openssl.cc"],
    hdrs = ["openssl.h"],
)

Then sign_in.cc's includes might look like this:

#include "sign_in.h"
#include "src/openssl.h"

Arguments

Attributes
name	Name; required A unique name for this target.
actual	Label; optional The target to be aliased. This target must exist, but can be any type of rule (including bind). If this attribute is omitted, rules referring to this target in //external will simply not see this dependency edge. Note that this is different from omitting the bind rule completely: it is an error if an //external dependency does not have an associated bind rule.

local_repository

local_repository(name, path, repo_mapping)

Allows targets from a local directory to be bound. This means that the current repository can use targets defined in this other directory. See the bind section for more details.

Examples

Suppose the current repository is a chat client, rooted at the directory ~/chat-app. It would like to use an SSL library which is defined in a different repository: ~/ssl. The SSL library has a target //src:openssl-lib.

The user can add a dependency on this target by adding the following lines to ~/chat-app/WORKSPACE:

local_repository(
    name = "my-ssl",
    path = "/home/user/ssl",
)

Targets would specify @my-ssl//src:openssl-lib as a dependency to depend on this library.

Arguments

Attributes
name	Name; required A unique name for this target.
path	String; required The path to the local repository's directory. This must be a path to the directory containing the repository's WORKSPACE file. The path can be either absolute or relative to the main repository's WORKSPACE file.
repo_mapping	Dictionary: String -> String; optional A dictionary from local repository name to global repository name. This allows controls over workspace dependency resolution for dependencies of this repository. For example, an entry "@foo": "@bar" declares that, for any time this repository depends on "@foo" (such as a dependency on "@foo//some:target"), it should actually resolve that dependency within globally-declared "@bar" ("@bar//some:target").

new_local_repository

new_local_repository(name, build_file, build_file_content, path, repo_mapping, workspace_file, workspace_file_content)

Allows a local directory to be turned into a Bazel repository. This means that the current repository can define and use targets from anywhere on the filesystem.

This rule creates a Bazel repository by creating a WORKSPACE file and subdirectory containing symlinks to the BUILD file and path given. The build file should create targets relative to the path. For directories that already contain a WORKSPACE file and a BUILD file, the local_repository rule can be used.

Examples

Suppose the current repository is a chat client, rooted at the directory ~/chat-app. It would like to use an SSL library which is defined in a different directory: ~/ssl.

The user can add a dependency by creating a BUILD file for the SSL library (~/chat-app/BUILD.my-ssl) containing:

java_library(
    name = "openssl",
    srcs = glob(['*.java'])
    visibility = ["//visibility:public"],
)

Then they can add the following lines to ~/chat-app/WORKSPACE:

new_local_repository(
    name = "my-ssl",
    path = "/home/user/ssl",
    build_file = "BUILD.my-ssl",
)

This will create a @my-ssl repository that symlinks to /home/user/ssl. Targets can depend on this library by adding @my-ssl//:openssl to a target's dependencies.

You can also use new_local_repository to include single files, not just directories. For example, suppose you had a jar file at /home/username/Downloads/piano.jar. You could add just that file to your build by adding the following to your WORKSPACE file:

new_local_repository(
    name = "piano",
    path = "/home/username/Downloads/piano.jar",
    build_file = "BUILD.piano",
)

And creating the following BUILD.piano file:

java_import(
    name = "play-music",
    jars = ["piano.jar"],
    visibility = ["//visibility:public"],
)

Then targets can depend on @piano//:play-music to use piano.jar.

Arguments

Attributes
name	Name; required A unique name for this target.
build_file	String; optional A file to use as a BUILD file for this directory. Either build_file or build_file_content must be specified. This attribute is a label relative to the main workspace. The file does not need to be named BUILD, but can be. (Something like BUILD.new-repo-name may work well for distinguishing it from the repository's actual BUILD files.)
build_file_content	String; optional The content for the BUILD file for this repository. Either build_file or build_file_content must be specified.
path	String; required A path on the local filesystem. This can be either absolute or relative to the main repository's WORKSPACE file.
repo_mapping	Dictionary: String -> String; optional A dictionary from local repository name to global repository name. This allows controls over workspace dependency resolution for dependencies of this repository. For example, an entry "@foo": "@bar" declares that, for any time this repository depends on "@foo" (such as a dependency on "@foo//some:target"), it should actually resolve that dependency within globally-declared "@bar" ("@bar//some:target").
workspace_file	String; optional The file to use as the WORKSPACE file for this repository. Either workspace_file or workspace_file_content can be specified, but not both. This attribute is a label relative to the main workspace. The file does not need to be named WORKSPACE, but can be. (Something like WORKSPACE.new-repo-name may work well for distinguishing it from the repository's actual WORKSPACE files.)
workspace_file_content	String; optional The content for the WORKSPACE file for this repository. Either workspace_file or workspace_file_content can be specified, but not both.