Apache Flink is maintained, improved, and extended by code contributions of volunteers. We welcome contributions to Flink, but due to the size of the project and to preserve the high quality of the code base, we follow a contribution process that is explained in this document.
Please feel free to ask questions at any time. Either send a mail to the dev mailing list or comment on the Jira issue you are working on.
IMPORTANT: Please read this document carefully before starting to work on a code contribution. Follow the process and guidelines explained below. Contributing to Apache Flink does not start with opening a pull request. We expect contributors to reach out to us first to discuss the overall approach together. Without consensus with the Flink committers, contributions might require substantial rework or will not be reviewed.
If you have a good idea for the contribution, you can proceed to the code contribution process. If you are looking for what you could contribute, you can browse open Jira issues in Flink’s bug tracker, which are not assigned, and then follow the code contribution process. If you are very new to the Flink project and want to learn about it and its contribution process, you can check the starter issues, which are annotated with a starter label.
Create a Jira ticket or mailing list discussion and reach consensus
Agree on importance, relevance, scope of the ticket, discuss the implementation approach and find a committer willing to review and merge the change.
Only committers can assign a Jira ticket.
Open a pull request and work with the reviewer.
Pull requests belonging to unassigned Jira tickets or not authored by assignee will not be reviewed or merged by the community.
[hotfix]pull request, without a Jira ticket.
The first step for making a contribution to Apache Flink is to reach consensus with the Flink community. This means agreeing on the scope and implementation approach of a change.
In most cases, the discussion should happen in Flink’s bug tracker: Jira.
The following types of changes require a
[DISCUSS] thread on the firstname.lastname@example.org Flink mailing list:
Do not open a Jira ticket for these types of changes before the discussion has come to a conclusion. Jira tickets based on a dev@ discussion need to link to that discussion and should summarize the outcome.
Requirements for a Jira ticket to get consensus:
If a change is identified as a large or controversial change in the discussion on Jira, it might require a Flink Improvement Proposal (FLIP) or a discussion on the dev mailing list to reach agreement and consensus.
Contributors can expect to get a first reaction from a committer within a few days after opening the ticket. If a ticket doesn’t get any attention, we recommend reaching out to the developer mailing list. Note that the Flink community sometimes does not have the capacity to accept all incoming contributions.
Once all requirements for the ticket are met, a committer will assign somebody to the
Assignee field of the ticket to work on it.
Only committers have the permission to assign somebody.
Pull requests belonging to unassigned Jira tickets will not be reviewed or merged by the community.
Once you’ve been assigned to a Jira issue, you may start to implement the required changes.
Here are some further points to keep in mind while implementing:
Considerations before opening a pull request:
mvn clean verifyis passing on your changes to ensure that all checks pass, the code builds and that all tests pass.
Considerations before or right after opening a pull request:
Code changes in Flink are reviewed and accepted through GitHub pull requests.
There is a separate guide on how to review a pull request, including our pull request review process. As a code author, you should prepare your pull request to meet all requirements.
The code will be merged by a committer of Flink once the review is finished. The Jira ticket will be closed afterwards.