How To Contribute

Contributions are welcome to all Apache Accumulo repositories. While most contributions are code, there are other ways to contribute to Accumulo:

  • answer questions on mailing lists
  • review pull requests
  • verify and test new releases
  • update the Accumulo website and documentation

Contributions are reviewed (via GitHub pull requests) by the community before being merged by a committer.

This document provides basic instructions for contributing to Accumulo. If you are looking for more information, check out the more comprehensive contributor guide.


Any contribution should have a corresponding issue. Accumulo uses JIRA for issue tracking. Before creating an issue, you will need to create an Apache JIRA account. If you need help finding an issue to work on, check out the open issues labeled for newbies or contact us.


Contributions can be made to the following repositories. While the general contribution workflow is described below, repositories have special instructions in their file which can be viewed by clicking on contribute in the Links column below.

Repository Links Description
Accumulo contribute Core Project
Accumulo Website contribute Source for this website
Accumulo Examples contribute Accumulo example code
Accumulo Testing contribute Accumulo test suites such as continuous ingest and random walk
Accumulo Docker contribute Source for Accumulo Docker image
Accumulo Wikisearch contribute Accumulo example application that indexes and queries Wikipedia data

Contribution workflow

  1. Create an Apache JIRA account (for issue tracking) and GitHub account (for pull requests).
  2. Find an issue to work on or create one that describes the work that you want to do.
  3. Fork and clone the GitHub repository that you want to contribute to.
  4. Create a branch in the local clone of your fork.
     git checkout -b accumulo-4321
  5. Do work and commit to your branch. You can reference this link for a guide on how to write good commit log messages.
  6. Ensure you works satisfies the guidelines laid out in the file.
  7. If needed, squash to the minimum number of commits. For help on squashing commits, see this tutorial or StackOverflow answer.
  8. Push your branch to your fork.
     git push origin accumulo-4321
  9. Create a Pull Request on GitHub to the appropriate repository. If the work is not complete and the Pull Request is for feedback, please put [WIP] in the subject.
  10. At least one committer (and others in the community) will review your pull request and add any comments to your code.
  11. Push any changes from the review to the branch as new commits so the reviewer only needs to review new changes. Please avoid squashing commits after the review starts. Squashing makes it hard for the reviewer to follow the changes.
  12. Repeat this process until a reviewer approves the pull request.
  13. When the review process is finished, all commits on the pull request may be squashed by a committer. Please avoid squashing as it makes it difficult for the committer to know if they are merging what was reviewed.

Coding Guidelines

  • If a change needs to go into multiple branches of Accumulo, it should be merged into earlier branches then later branches.
  • Accumulo follows semver for its public API. Accumulo lists which packages are public API in its
  • Every file requires the ASF license header as described in ASF Source Header.
  • Remove all trailing whitespaces. Eclipse users can use Source→Cleanup option to accomplish this.
  • Use 2 space indents and never use tabs!
  • Use 160-column line width for Java code and Javadoc.
  • Use a new line with single statement if/else blocks.
  • Do not use Author Tags. The code is developed and owned by the community.

Code Editors

Feel free to use any editor when contributing Accumulo. If you are looking for a recommendation, many Accumulo developers use IntelliJ or Eclipse. Below are some basic instructions to help you get started.


  1. Download and install IntelliJ
  2. Clone the Accumulo repository that you want to work on.
    git clone
  3. Import the repository as a Maven project into IntelliJ
  4. (Optional) Download and import Eclipse-Accumulo-Codestyle.xml from Accumulo’s contrib directory
    • Import via File > Settings > Code Style and clicking on cog wheel


  1. Download and install Eclipse.
  2. Clone the Accumulo repository that you want to work on.
    git clone
  3. Import the repository as a Maven project into Eclipse
  4. (Optional) Download and import Eclipse formatting and style guides from Accumulo’s contrib directory
    • Import Formatter: Preferences > Java > Code Style > Formatter and import the Eclipse-Accumulo-Codestyle.xml downloaded in the previous step.
    • Import Template: Preferences > Java > Code Style > Code Templates and import the Eclipse-Accumulo-Template.xml. Make sure to check the “Automatically add comments” box. This template adds the ASF header and so on for new code.

For more details, see the contributor guide.