Linkage Monitor works as a presubmit check in a GitHub repository to prevent open source libraries in the Google Cloud Java orbit (GAX, google-http-java-client, gRPC, etc.) from releasing versions that introduce new linkage errors.

User documentation: Linkage Monitor

This tool will work as part of presubmit checks in the library projects in GitHub. This check will notify when code or a dependency changes in such a way as to introduce a new linkage error in Google Cloud Libraries BOM;

Example presubmit build script:

set -e # fail if any of command fails
# Install artifacts in the local Maven repository. The command depends on build system of the project.
mvn install -DskipTests

# For Gradle,
# ./gradlew build publishToMavenLocal -x test

# Get uber JAR unless it's installed already
curl https://storage.googleapis.com/.../linkage-monitor-latest-all-deps.jar 
java -jar linkage-monitor-X.Y.Z-all-deps.jar com.google.cloud:libraries-bom

Kokoro job to update the GCS object is cloud-opensource-java/ubuntu/linkage-monitor-gcs.