Generate external dependencies from Maven projects
generate_workspace helps automate the process of writing
the WORKSPACE file for a Java project. This tool is
helpful when the list of external dependencies is long, such as when working
with external transitive dependencies.
generate_workspace tool will generate a
generated_maven_jarsmacro that will contain the transitive dependencies, and
generated_java_librariesmacro that will contain a library for each maven_jar.
Bazel’s binary installer does not include
generate_workspace. To be able to
use this tool:
Clone Bazel’s migration tooling repo:
git clone https://github.com/bazelbuild/migration-tooling.git
Run the following to build the
generate_workspacetool and see usage:
bazel run //generate_workspace
Generate a list of external dependencies
When you run the tool, you can specify Maven projects (that is, directories containing a
pom.xmlfile), or Maven artifact coordinates directly. For example:
$ bazel run //generate_workspace -- \ > --maven_project=/path/to/my/project \ > --artifact=groupId:artifactId:version \ > --artifact=groupId:artifactId:version \ > --repositories=https://jcenter.bintray.com Wrote /usr/local/.../generate_workspace.runfiles/__main__/generate_workspace.bzl
The tool creates one outputs, a
generate_workspace.bzlfile that contains two macros:
generated_maven_jarsmacro that will contain the transitive dependencies of the given projects and artifacts.
generated_java_librariesmacro will contain a library for each maven_jar.
If you specify multiple Maven projects or artifacts, they will all be combined into one
generate_workspace.bzlfile. For example, if an artifact depends on junit and the Maven project also depends on junit, then junit will only appear once as a dependency in the output.
generate_workspace.bzlfile to your workspace. The
.bzlfile’s original location is listed in the commandline output.
To access external dependencies:
Add the following to your WORKSPACE file:
load("//:generate_workspace.bzl", "generated_maven_jars") generated_maven_jars()
You can now access any of the jars in
This reference points to the jar, but not to any dependencies that the jar itself may have. To have a target depend on one of these jars, you must list the jar as well as each of that jar’s dependencies.
For example, to depend on the Guava jar from the Guava project, in the target definition you will need to list the jar and its transitive dependencies:
deps = [ "@com_google_guava_guava//jar", "@com_google_code_findbugs_jsr305//jar", "@com_google_errorprone_error_prone_annotations//jar", "@com_google_j2objc_j2objc_annotations//jar", ]
Optionally, you can also access the libraries. When you list a library as a dependency, the transitive dependencies are already included, and so you don’t need to list them manually.
To access the libraries, add the following to a BUILD file:
load("//:generate_workspace.bzl", "generated_java_libraries") generated_java_libraries()
The recommended location for this BUILD file is in a directory called
You can now access any of the Java library targets in
For example, for a target to depend on Guava and its transitive dependencies, in the target definition you will need to list:
deps = ["//third_party:com_google_guava_guava"]
generate_workspace.bzllists the correct version of each dependency.
If several different versions of an artifact are requested (for example, by different libraries that depend on it), then
generate_workspacechooses a version and annotates the
maven_jarwith the other versions requested.
Here’s an example of the contents of
# org.springframework:spring:2.5.6 # javax.mail:mail:1.4 # httpunit:httpunit:1.6 wanted version 1.0.2 # org.springframework:spring-support:2.0.2 wanted version 1.0.2 # org.slf4j:nlog4j:1.2.24 wanted version 1.0.2 native.maven_jar( name = "javax_activation_activation", artifact = "javax.activation:activation:1.1", )
The example above indicates that
org.slf4j:nlog4j:1.2.24all depend on
javax.activation. However, two of these libraries wanted version 1.1 and three of them wanted 1.0.2. The WORKSPACE file is using version 1.1, but that might not be the right version to use.