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This project is in an early stage of development. It is subject to change without warning. Do not use this code for production work.

###GATK 4 (codename Hellbender)

The public parts of the next generation of GATK/Picard methods engine and tools.

This project is in a pre-alpha development stage and is not yet ready for general use.

If you are looking for the current version of GATK to use in production work, please see the GATK website, where you can download a precompiled executable, read documentation, ask questions and receive technical support.

If you are looking for the codebase of the current production version of GATK, please see either the GATK development framework repository or the full GATK tools repository.


  • Java 8

  • Gradle 2.7

  • R 3.1.3

  • Git 2.5

  • The git-lfs plugin. Run git lfs init after installing, followed by git lfs pull to download the large files. We recommend v0.6.0 but newer versions may also work.

##Installation To build and run all tests, run gradle check. Test report is in build/reports/tests/index.html.

To only build, run gradle installDist.

To run all tests, run gradle test. What will happen depends on the value of the CLOUD environment variable: if it's false or unset then only local tests are run. If it's mandatory then it'll run only the cloud tests.

To run a single test class, run something like this, gradle test -Dtest.single=ReadUtilsUnitTest.

To run tests and compute coverage reports, run gradle jacocoTestReport. The report is then in build/reports/jacoco/test/html/index.html. (IntelliJ 14 has a good coverage tool that is preferable for development).

Note: for faster gradle operations, add org.gradle.daemon=true to your ~/.gradle/ file. This will keep a gradle daemon running in the background and avoid the ~6s gradle start up time on every command.

##Running GATK4 To run the main program locally, run build/install/gatk/bin/gatk.

For spark tools, first build the Spark jar using gradle sparkJar. The jar can be found in build/libs/ and will have a name that matches the pattern gatk-all-4.pre-alpha-7-*-SNAPSHOT-spark.jar, where * is the hash of the current commit.

There are three main ways to run GATK4 with Spark,

  • Locally, using the regular gatk jar and --sparkMaster 'local[*]'

  • On an on-premises cluster by copying the spark jar to the master and running spark-submit

  • On Google Cloud Dataproc. For detailed instructions, see our Clould Dataproc wiki page

##General guidelines for GATK4 developers

  • Do not put private or restricted data into the repo.

  • Try to keep datafiles under 100kb in size. Larger test files should go into src/test/resources/large, and must be managed using git lfs by running git lfs track <file> on each new large file before commit.

  • GATK4 is BSD licensed. The license is in the top level LICENSE.TXT file. Do not add any additional license text or accept files with a license included in them.

  • Each tool should have at least one good end-to-end integration test with a check for expected output, plus high-quality unit tests for all non-trivial utility methods/classes used by the tool. Although we have no specific coverage target, coverage should be extensive enough that if tests pass, the tool is guaranteed to be in a usable state.

  • All newly written code must have good test coverage (>90%).

  • All bug fixes must be accompanied by a regression test.

  • All pull requests must be reviewed before merging to master (even documentation changes).

  • Don't issue or accept pull requests that introduce warnings. Warnings must be addressed or suppressed.

  • Don't issue or accept pull requests that significantly decrease coverage (less than 1% decrease is sort of tolerable).

  • Don't override clone() unless you really know what you're doing. If you do override it, document thoroughly. Otherwise, prefer other means of making copies of objects.

  • Don't use toString() for anything other than human consumption (ie. don't base the logic of your code on results of toString().)

  • For logging, use org.apache.logging.log4j.Logger

  • We mostly follow the Google Java Style guide

  • Git: Don't push directly to master - make a pull request instead.

  • Git: Rebase and squash commits when merging.

  • If you push to master or mess the commit history, you owe us 1 growler or tasty snacks at happy hour. If you break the master build, you owe 3 growlers (or lots of tasty snacks). Beer may be replaced by wine (in the color and vintage of buyer's choosing) in proportions of 1 growler = 1 bottle.

##Tests We use Travis-CI as our continuous integration provider.

  • Before merging any branch make sure that all required tests pass on travis.
  • Every travis build will upload the test results to our gatk google bucket. A link to the uploaded report will appear at the very bottom of the travis log. Look for the line that says See the test report at. If TestNG itself crashes there will be no report generated.

##R Dependency Certain GATK tools may optionally generate plots if R is installed. We recommend R v3.1.3 if you want to produce plots. If you are uninterested in plotting, R is still required by several of the unit tests. Plotting is currently untested and should be viewed as a convinience rather than a primary output.

R installation is not part of the gradle build. See for general information on installing R for your system.

brew tap homebrew/science
brew install R

The plotting R scripts require certain R packages to be installed. You can install these by running scripts/install_R_packages.R. Either run it as superuser to force installation into the sites library or run interactively and create a local library.

sudo Rscript scripts/install_R_packages.R



##Creating a GATK project in the IntelliJ IDE:

  • Ensure that you have gradle and the Java 8 JDK installed

  • Install the TestNG plugin (in preferences)

  • Clone the GATK repository using git

  • In IntelliJ, go to File -> "Import Project"

  • Select the root directory of your GATK clone, then "Ok"

  • Select "Import project from external model", then "Gradle", then "Next"

  • Ensure that "Gradle project" points to the build.gradle file in the root of your GATK clone

  • Select "Use auto-import" and "Use default gradle wrapper".

  • Click "Finish"

  • After downloading project dependencies, IntelliJ should open a new window with your GATK project

  • In File -> "Project Structure" -> "Project", set the "Project SDK" to your Java 1.8 JDK, and "Project language level" to 8 (you may need to add your Java 8 JDK under "Platform Settings" -> SDKs if it isn't there already). Then click "Apply"/"Ok".

##Setting up debugging in IntelliJ

  • Follow the instructions above for creating an IntelliJ project for GATK

  • Go to Run -> "Edit Configurations", then click "+" and add a new "Application" configuration

  • Set the name of the new configuration to something like "GATK debug"

  • For "Main class", enter org.broadinstitute.hellbender.Main

  • Ensure that "Use classpath of module:" is set to use the "gatk" module's classpath

  • Enter the arguments for the command you want to debug in "Program Arguments"

  • Click "Apply"/"Ok"

  • Set breakpoints, etc., as desired, then select "Run" -> "Debug" -> "GATK debug" to start your debugging session

  • In future debugging sessions, you can simply adjust the "Program Arguments" in the "GATK debug" configuration as needed

##Updating the Intellij project when dependencies change If there are dependency changes in build.gradle it is necessary to refresh the gradle project. This is easily done with the following steps.

  • Open the gradle tool window ( "View" -> "Tool Windows" -> "Gradle" )
  • Click the refresh button in the Gradle tool window. It is in the top left of the gradle view and is represented by two blue arrows.

##Uploading Archives to Sonatype (to make them available via maven central) To upload snapshots to Sonatype you'll need the following:

  • You must have a registered account on the sonatype JIRA (and be approved as a gatk uploader)

  • You need to configure several additional properties in your /~.gradle/ file

  • If you want to upload a release instead of a snapshot you will additionally need to have access to the gatk signing key and password

#needed for snapshot upload
sonatypeUsername=<your sonatype username>
sonatypePassword=<your sonatype password>

#needed for signing a release
signing.keyId=<gatk key id>
signing.password=<gatk key password>

To perform an upload, use

gradle uploadArchives

Currently all builds are considered snapshots. The archive name is based off of git describe.

###How to contribute (Note: section inspired by, and some text copied from, Apache Parquet)

We welcome all contributions to the GATK project. The contribution can be a issue report or a pull request. If you're not a committer, you will need to make a fork of the gatk repository and issue a pull request from your fork.

To become a committer, you need to make several high-quality code contributions and be approved by the current committers.

For ideas on what to contribute, check issues labeled "Help wanted (Community)". Comment on the issue to indicate you're interested in contibuting code and for sharing your questions and ideas.

To contribute a patch:

  • Break your work into small, single-purpose patches if possible. It’s much harder to merge in a large change with a lot of disjoint features.
  • Submit the patch as a GitHub pull request against the master branch. For a tutorial, see the GitHub guides on forking a repo and sending a pull request. If applicable, include the issue number in the pull request name.
  • Make sure that your code passes all our tests. You can run the tests with gradle test in the root directory.
  • Add tests for all new code you've written. We prefer unit tests but high quality integration tests that use small amounts of data are acceptable.
  • Follow the General guidelines for GATK4 developers.

We tend to do fairly close readings of pull requests, and you may get a lot of comments. Some things to consider:

  • Write tests for all new code.
  • Document all classes and public methods.
  • For all public methods, check validity of the arguments and throw IllegalArgumentException if invalid.
  • Use braces for control constructs, if, for etc.
  • Make classes, variables, parameters etc final unless there is a strong reason not to.
  • Give your operators some room. Not a+b but a + b and not foo(int a,int b) but foo(int a, int b).
  • Generally speaking, stick to the Google Java Style guide

Thank you for getting involved!


  • GATK forum for general discussions on how to use the GATK.
  • Issue tracker to report errors and enhancement ideas.
  • Discussions also take place in github pull requests
  • For committers, we have a publicly-visible google group gatk-dev
  • For committers, we have a hipchat room at the Broad called 'Hellbender (aka GATK4)'.

##Authors The authors list is maintained in the AUTHORS file. See also the Contributors list at github.

##License Licensed under the BSD License. See the LICENSE.txt file.