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DataHub Developer's Guide

Pre-requirements

  • Java 1.8 SDK

  • Docker

  • Docker Compose

  • Docker engine with at least 8GB of memory to run tests.

    note

    Do not try to use a JDK newer than JDK 8. The build process does not work with newer JDKs currently.

Building the Project

Fork and clone the repository if haven't done so already

git clone https://github.com/{username}/datahub.git

Change into the repository's root directory

cd datahub

Use gradle wrapper to build the project

./gradlew build

Note that the above will also run run tests and a number of validations which makes the process considerably slower.

We suggest partially compiling DataHub according to your needs:

  • Build Datahub's backend GMS (Generalized metadata service):
./gradlew :metadata-service:war:build
  • Build Datahub's frontend:
./gradlew :datahub-frontend:dist -x yarnTest -x yarnLint
  • Build DataHub's command line tool:
./gradlew :metadata-ingestion:installDev
  • Build DataHub's documentation:
./gradlew :docs-website:yarnLintFix :docs-website:build -x :metadata-ingestion:runPreFlightScript
# To preview the documentation
./gradlew :docs-website:serve

Deploying local versions

Run just once to have the local datahub cli tool installed in your $PATH

cd smoke-test/
python3 -m venv venv
source venv/bin/activate
pip install --upgrade pip wheel setuptools
pip install -r requirements.txt
cd ../

Once you have compiled & packaged the project or appropriate module you can deploy the entire system via docker-compose by running:

datahub docker quickstart --build-locally

Replace whatever container you want in the existing deployment. I.e, replacing datahub's backend (GMS):

(cd docker && COMPOSE_DOCKER_CLI_BUILD=1 DOCKER_BUILDKIT=1 docker-compose -p datahub -f docker-compose-without-neo4j.yml -f docker-compose-without-neo4j.override.yml -f docker-compose.dev.yml up -d --no-deps --force-recreate datahub-gms)

Running the local version of the frontend

(cd docker && COMPOSE_DOCKER_CLI_BUILD=1 DOCKER_BUILDKIT=1 docker-compose -p datahub -f docker-compose-without-neo4j.yml -f docker-compose-without-neo4j.override.yml -f docker-compose.dev.yml up -d --no-deps --force-recreate datahub-frontend-react)

IDE Support

The recommended IDE for DataHub development is IntelliJ IDEA. You can run the following command to generate or update the IntelliJ project file

./gradlew idea

Open datahub.ipr in IntelliJ to start developing!

For consistency please import and auto format the code using LinkedIn IntelliJ Java style.

Common Build Issues

Getting Unsupported class file major version 57

You're probably using a Java version that's too new for gradle. Run the following command to check your Java version

java --version

While it may be possible to build and run DataHub using newer versions of Java, we currently only support Java 1.8 (aka Java 8). Plan for Java 11 migration is being discussed in this issue.

Getting cannot find symbol error for javax.annotation.Generated

Similar to the previous issue, please use Java 1.8 to build the project. You can install multiple version of Java on a single machine and switch between them using the JAVA_HOME environment variable. See this document for more details.

:metadata-models:generateDataTemplate task fails with java.nio.file.InvalidPathException: Illegal char <:> at index XX or Caused by: java.lang.IllegalArgumentException: 'other' has different root error

This is a known issue when building the project on Windows due a bug in the Pegasus plugin. Please build on a Mac or Linux instead.

As we generate quite a few files from the models, it is possible that old generated files may conflict with new model changes. When this happens, a simple ./gradlew clean should reosolve the issue.

Execution failed for task ':metadata-service:restli-servlet-impl:checkRestModel'

This generally means that an incompatible change was introduced to the rest.li API in GMS. You'll need to rebuild the snapshots/IDL by running the following command once

./gradlew :metadata-service:restli-servlet-impl:build -Prest.model.compatibility=ignore

java.io.IOException: No space left on device

This means you're running out of space on your disk to build. Please free up some space or try a different disk.