Awesome

rules_maven

Bazel rules for working with transitive maven dependencies.

The word 'maven' here refers to 'maven artifacts', not the tool 'mvn'. This repo utilizes gradle to assist with transitive dependency management, hence the logo reference.

Rules

Status: experimental, but actively in use for other internal projects.

Usage

1. Add rules_maven to your WORKSPACE

git_repository(
  name = "org_pubref_rules_maven",
  remote = "https://github.com/pubref/rules_maven",
  commit = HEAD, # replace with latest version
)

load("@org_pubref_rules_maven//maven:rules.bzl", "maven_repositories")
maven_repositories()

2a. Define an initial maven_repository rule naming the root artifact(s)

load("@org_pubref_rules_maven//maven:rules.bzl", "maven_repository")

maven_repository(
  name = "guice",
  deps = [
    'com.google.inject:guice:4.1.0',
  ],
)

Given this initial repository rule defintion, rules_maven will:

1. write a build.gradle file,

2. install gradle as it's own internal dependency (first time only; does not interfere with any other gradle you might have installed).

3. call gradle dependencies and parse the output,

4. fetch the expected sha1 values for named artifacts,

5. write a @guice//:rules.bzl file having the requisite maven_jar rules (organized by configuration),

6. write a @guice//:BUILD file with the requisite java_library that bundle/export dependencies (one per configuration).

7. print out a formatted maven_repository "hermetic-form" rule with all the transitive dependencies and their sha1 values explicitly named (can be disabled via the hermetic = False attribute)

2b. Copy and paste the closed-form back into your WORKSPACE.

rules_maven will regurgitate a so-called closed-form maven_repository rule enumerating the transitive dependencies and their sha1 values in the transitive_deps attribute. Assuming you trust the data, copy and paste this back into your WORKSPACE.

maven_repository(
  name = 'guice',
  deps = [
    'com.google.inject:guice:4.1.0',
  ],
  transitive_deps = [
    '0235ba8b489512805ac13a8f9ea77a1ca5ebe3e8:aopalliance:aopalliance:1.0',
    '6ce200f6b23222af3d8abb6b6459e6c44f4bb0e9:com.google.guava:guava:19.0',
    'eeb69005da379a10071aa4948c48d89250febb07:com.google.inject:guice:4.1.0',
    '6975da39a7040257bd51d21a231b76c915872d38:javax.inject:javax.inject:1',
  ],
)

Once the transitive_deps is stable (all transitive deps and their correct sha1 values are listed), rules_maven will be silent.

Note: make sure you leave out the artifact ID type, rules_maven will get confused about it. For example, don't say com.google.inject:guice:jar:4.1.0 (leave out the :jar substring).

3. Load the @guice//:rules.bzl file in your WORKSPACE and invoke the desired macro configuration.

The rules.bzl file (a generated file) contains macro definitions that ultimately define native.maven_jar rules. A separate macro is defined for each gradle configuration. The default configurations are: compile, runtime, compileOnly, compileClasspath, testCompile, and testRuntime. (these can be customized via the configurations attribute).

The name of the macros are the gradle configuration name, prefixed with the rule name. In this case there are the following macros (and several others):

• guice_compile: Provide compile-time dependencies.
• guice_runtime: Provide runtime-time dependencies.
• ...

load("@guice//:rules.bzl", "guice_compile")
guice_compile()

In this case, both _compile and _runtime macros provide the same dependencies.

You can inspect the contents of the generated file via:

$ cat $(bazel info output_base)/external/guice/rules.bzl

4. Depend on the java_library rule for the desired configuration.

java_binary(
  name = "app",
  main_class = "example.App",
  deps = ["@guice//:compile"],
)

Final WORKSPACE

To further illustrate steps 1-3 are all in the same file.

git_repository(
  name = "org_pubref_rules_maven",
  remote = "https://github.com/pubref/rules_maven",
  commit = HEAD, # replace with latest version
)
load("@org_pubref_rules_maven//maven:rules.bzl", "maven_repositories", "maven_repository")
maven_repositories()


maven_repository(
  name = 'guice',
  deps = [
    'com.google.inject:guice:4.1.0',
  ],
  transitive_deps = [
    '0235ba8b489512805ac13a8f9ea77a1ca5ebe3e8:aopalliance:aopalliance:1.0',
    '6ce200f6b23222af3d8abb6b6459e6c44f4bb0e9:com.google.guava:guava:19.0',
    'eeb69005da379a10071aa4948c48d89250febb07:com.google.inject:guice:4.1.0',
    '6975da39a7040257bd51d21a231b76c915872d38:javax.inject:javax.inject:1',
  ],
)
load("@guice//:rules.bzl", "guice_compile")
guice_compile()

maven_repository attributes

experimental_disambiguate_maven_jar_workspace_names: This option changes the name of the generated workspace name for maven_jar rules. For example, consider the artifact com.google.guava:guava:20.0. The corresponding workspace name under default conditions is com_google_guava_guava. If experimental_disambiguate_maven_jar_workspace_names = True, the workspace name includes the version specifier and becomes com_google_guava_guava_20_0.

Example use of the repositories attribute:

# Load commons-imaging from adobe nexus repository.
# Load everything else (junit) from maven central.
maven_repository(
    name = "maven",
    repositories = {
        "https://repo.adobe.com/nexus/content/repositories/public/": [
            "org.apache.commons:commons-imaging",
        ],
    },
    deps = [
        "junit:junit:4.12",
        "org.apache.commons:commons-imaging:1.0-R1534292",
    ],
)

Credits

The anteater image is a reference to the O'Reilly book cover. This image is actually "Peter", the University of California Irvine mascot. ZOT!