tighterman/migration-tooling

Migration tools for Bazel

Migration tooling

This repository contains tools used for migrating existing projects to Bazel.

Maven-to-Bazel

To migrate a Maven project to Bazel, build:

bazel run //generate_workspace -- --maven_project=/path/to/maven/project

This will create a file generate_workspace.bzl. Copy it to your workspace and add the following to your WORKSPACE file:

load("//:generate_workspace.bzl", "generated_maven_jars")
generated_maven_jars()

Then you can access any of the jars in generate_workspace.bzl.

Optionally, add the following to a BUILD file:

load("//:generate_workspace.bzl", "generated_java_libraries")
generated_java_libraries()

Then you can access any of the Java library targets in generate_workspace.bzl, which export each jar's dependencies as well as the jar itself.

transitive_maven_jar

The transitive_maven_jar repository rule exposes the specified Maven jars, as well as their transitive dependencies under one target. This alleviates the need to run generate_workspace whenever dependencies change. However, it comes at the cost of re-fetching dependencies.

As a prerequisite for use, you must have bazel 0.5.2 or later installed. In addition, add the following to your WORKSPACE file:

http_archive(
	name = "trans_maven_jar",
	url = "https://github.com/bazelbuild/migration-tooling/archive/master.zip",
	type = "zip",
	strip_prefix = "migration-tooling-master",
)

load("@trans_maven_jar//transitive_maven_jar:transitive_maven_jar.bzl", "transitive_maven_jar")

Now, within your WORKSPACE file, you can define your external maven dependencies as follows

transitive_maven_jar(
	name = "dependencies",
	artifacts = [
		"something:something:4.0",
		"otherthing:otherthing:3.2",
		...
	]
)

load("@dependencies//:generate_workspace.bzl", "generated_maven_jars")
generated_maven_jars()

The transitive_maven_jar rule will resolve the transitive dependencies for the specified artifacts and then it will generate a generate_workspace.bzl which you must load in your WORKSPACE file.

Code

This code was inspired by the aether examples for walking maven dependencies.