rules_jvm_external

The rules_jvm_external Bzlmod extension collects artifacts from all tags with the same name attribute (defaulting to maven) across different Bzlmod modules and resolves them together.

Key Behaviors:

• Namespace Contributions: If multiple modules contribute to the same maven repository, a message will inform you which modules are involved. You can suppress this warning by adding the contributing modules to the known_contributing_modules attribute of the install tag.
• Version Conflicts: If different modules request different versions of the same artifact, the resolver uses the highest version found in the root and sub-modules.
• Resolution Warnings: If the root module's version is not the highest, you will see a warning during repinning. To fix this, either update the version in your root MODULE.bazel to the highest version or set force_version = True in the root module.

In Bzlmod, you cannot 'inline' exclusions within a maven.install(artifacts = [...]) list. Attempting to do so will cause a type error. Instead, use one of the following two methods:

Method 1: Use maven.artifact

Split the specific artifact into its own maven.artifact declaration to apply exclusions.

maven.artifact(
    artifact = "grpc-core",
    exclusions = ["io.grpc:grpc-util"],
    group = "io.grpc",
    version = "1.58.0",  # Must stay in sync with the version used in maven.install
)

maven.install(
    artifacts = [
        "junit:junit:4.13.2",
        # ...
    ],
)

Method 2: Use maven.amend_artifact

Use amend_artifact to modify an artifact that was declared elsewhere (e.g., in an install or from_toml tag). Matching is performed using the group:artifact tuple.

# Modifying an existing declaration
maven.amend_artifact(
    coordinates = "io.grpc:grpc-core",
    exclusions = ["io.grpc:grpc-util"],
)

To use rules_jvm_external with Bzlmod (required for Bazel 7+), add the dependency and the maven extension to your MODULE.bazel file. You can define dependencies using maven.install and provide specific overrides or additional options using maven.artifact. The maven.install and maven.artifact tags are merged automatically.

After installation, you must generate a lockfile to pin transitive dependencies.

Note on pinning: Due to a known issue, the generated lockfile name is long and non-standard. You must manually rename it to maven_install.json before referencing it in your MODULE.bazel.

bazel_dep(name = "rules_jvm_external", version = "...")
maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")

maven.install(
    artifacts = [
        "org.seleniumhq.selenium:selenium-java:4.4.0",
    ],
)

# Individual artifact overrides
maven.artifact(
    artifact = "javapoet",
    group = "com.squareup",
    neverlink = True,
    version = "1.11.1",
)

use_repo(maven, "maven")

Pinning workflow:

1. Run the pin program:

$ bazel run @maven//:pin

2. Rename the resulting file:

$ mv rules_jvm_external~4.5~maven~maven_install.json maven_install.json

3. Update MODULE.bazel to use the lockfile:

maven.install(
    ...
    lock_file = "//:maven_install.json",
)

You can import dependencies from a Gradle libs.versions.toml file using the maven.from_toml tag. This allows you to share dependency definitions between Gradle and Bazel.

rules_jvm_external supports several extended fields in the TOML file that are not part of the standard Gradle format. These must be provided as quoted strings within the inline table.

# In MODULE.bazel
maven.from_toml(
    libs_versions_toml = "//gradle:libs.versions.toml",
)

Example libs.versions.toml with extended fields:

[versions]
junitJupiter = "5.12.2"

[libraries]
guava = { module = "com.google.guava:guava" }
guavaBom = { module = "com.google.guava:guava-bom", version = "33.4.8-jre", is_bom = "true" }
junitApi = { module = "org.junit.jupiter:junit-jupiter-api", version.ref = "junitJupiter" }
clickhouse = { module = "com.clickhouse:clickhouse-jdbc", version = "0.9.2", classifier = "all", force_version = "true" }
misk = { module = "com.squareup.misk:misk-core", version = "1.0.0", exclusions = "['*:*']" }