maven-druid-build-optimization

name	maven-druid-build-optimization
description	How to build Apache Druid efficiently with Maven while skipping unnecessary checks and OOM-prone modules. Use this skill when building patched Druid versions, when rebuilding after security fixes, or when the web-console module causes out-of-memory errors.

Maven Druid Build Optimization

Overview

Apache Druid is a large project with extensive code quality checks and a heavy web-console module. When building a patched version or in memory-constrained environments, selective skipping of modules and checks optimizes build time and resource usage.

Build Command Structure

The standard optimized build for patched Druid skips:

• Web-console module (-pl '!web-console') - Frontend build with Node.js dependencies, causes OOM
• Unit tests (-DskipTests) - Can be skipped when applying security patches
• Code quality checks - Multiple style, security, and analysis tools

Full Build Command for Patched Druid

cd /root/druid
mvn clean package \
  -DskipTests \
  -Dcheckstyle.skip=true \
  -Dpmd.skip=true \
  -Dforbiddenapis.skip=true \
  -Dspotbugs.skip=true \
  -Danimal.sniffer.skip=true \
  -Denforcer.skip=true \
  -Djacoco.skip=true \
  -Ddependency-check.skip=true \
  -pl '!web-console' \
  -pl indexing-service \
  -am

Understanding the Flags

Module Selection

• -pl '!web-console' - Exclude web-console from build (prevents OOM)
• -pl indexing-service - Include only indexing-service module
• -am (--also-make) - Build dependencies of selected modules

Test Skipping

• -DskipTests - Skip test compilation and execution

Quality Check Skips

These skip code quality tools that can be safely bypassed for patched code:

• -Dcheckstyle.skip=true - Checkstyle code style checks
• -Dpmd.skip=true - PMD static analysis
• -Dforbiddenapis.skip=true - Forbidden APIs checks
• -Dspotbugs.skip=true - SpotBugs security analysis
• -Danimal.sniffer.skip=true - Animal Sniffer API compatibility
• -Denforcer.skip=true - Maven Enforcer rules
• -Djacoco.skip=true - Code coverage
• -Ddependency-check.skip=true - Dependency vulnerability checking

Build Phases

• clean - Remove previous build artifacts
• package - Compile and create JAR files

Build Output Location

Built artifacts (JAR files) are located at:

druid-indexing-service/target/druid-indexing-service-<version>-<classifier>.jar

Memory Management

If you still encounter OOM errors:

1. Increase Maven heap:

   export MAVEN_OPTS="-Xmx2g"
   

2. Build specific modules sequentially:

   mvn clean package -pl 'druid-core' -DskipTests -Dcheckstyle.skip=true ...
   mvn package -pl 'druid-indexing-service' -am -DskipTests -Dcheckstyle.skip=true ...
   

Verification After Build

After a successful build, verify the JAR was created:

ls -lh druid-indexing-service/target/*.jar

The verifier will deploy the JAR to /opt/druid/lib/ and restart the Druid service before running tests.

Build Troubleshooting

• Timeout issues: Increase Maven timeout: mvn -DmultiModuleProjectDirectory=. ...
• Out of memory: Use -Xmx4g or higher in MAVEN_OPTS
• Module not found: Verify module names with mvn -pl help:describe
• Dependency issues: Run mvn dependency:tree to verify dependency resolution