Contributing

Thank you for your interest in contributing to Apache Camel.

In this document, we provide some guidelines on approaching the Apache Camel community and how to contribute to the community in the best possible way.

Please remember that a community is much more than just code. There are many ways you can help make Camel a better piece of software. Please dive in and help!

Identify areas you can contribute initially. You don’t have to be an expert in an area, the Apache Camel developers are available to offer help and guidance.

Introduce yourself on the developers' mailing-list, tell us what area of work or problem you wish to address in Camel. Create a draft of your solution, which can be simple 1-2 sentences on the change you wish to make. Try to be as specific as you can: include a short description of your intent, what you tried and what did not work, or what you need help with. The best way of approaching the developers is by describing what you would like to work on and asking specific questions on how to get started. We will do our best to guide you and help you make your contribution.

We often participate in Google Summer of Code and Outreachy programs. For information about those, look at those program websites. If you wish to participate in either of those, follow the guidelines and schedule set by those programs. If you are unsure, please reach out using one of the communication channels, or ask on the developer’s mailing list for help.

Apache Camel is an Apache Software Foundation project. We do all communication in the open on the project mailing lists. You can read more on the reasoning behind this to get a better understanding of this.

There are various ways of communicating with the Camel community.

Subscribe to the developer’s mailing list for questions and guidance about how to contribute. To subscribe to the developer’s mailing list, you can send an e-mail to dev-subscribe@camel.apache.org.

You can check the mailing-list page for more information about Camel mailing lists and information about how to subscribe to each of them.

You can also reach us on the Zulip chat.

The Camel Core project uses the Apache Foundation Jira instance for tracking issues, tasks, and feature requests.

When creating a ticket on our issue tracker, please try to follow these guidelines:

Documentation is extremely important to help users make the most of Apache Camel, and it’s probably the area that needs the most help!

If you are interested in helping the documentation effort, whether it’s just to fix a page here or there, correct a link or even write a tutorial or improve existing documentation, please do dive in and help! Most of the documentation is managed in the same repositories as the related source code, so the process is similar to working on the code.

For more details, please refer to Improving the Documentation Guide in the User Manual.

We recommend forking the code from the camel GitHub repository.

Alternatively, if you are using the GitHub CLI:

Then, create a branch to work on your changes:

To build the project, you need Apache Maven.

If you need to implement tests for your changes (highly recommended!), you will probably need to handle 3 separate things: - simulate the infrastructure required for the test (i.e.; JMS brokers, Kafka, etc), - writing testable code, - the test logic itself.

Naturally, there is no rule of thumb for how the code changes, and test logic should be written. The Testing page in the User Manual provides detailed information and examples for writing Camel unit tests.

Concerning simulating the test infrastructure, Camel has a growing library of reusable components that can be helpful: the test infra components. These components are located in the test-infra module and provide support for simulating message brokers, cloud environments, databases, and much more.

Using these components is usually as simple as registering them as JUnit 5 extensions:

Then you can access the service by using the methods and properties provided by the services. This varies according to each service.

If you need to implement a new test-infra service, check the readme on the test-infra module for additional details.

Apache Camel source code uses a coding style/format that can be verified for compliance using the "checkstyle" plugin.

To enable source style checking, build Camel with the -Psourcecheck profile:

Please remember to run this check on your code changes before submitting a patch or GitHub PR. You do not need to run this against the entire project, but only in the modules you modified.

For instance, if you do some code changes in the camel-ftp component, following which you can run the check from within this directory:

We gladly accept patches if you can find ways to improve, tune, or fix Camel in some way.

Make sure you have followed the steps and guidelines outlined in this document. For larger changes, make sure that you have discussed them on the developer’s mailing list or in the Jira issue tracker beforehand.

To get the best response from the team, make sure that the reasoning behind the contribution you wish to make is clear: outline the problem and explain your solution for it. Describe any changes you have made for which you are unaware or unsure of any consequences or side effects.

Be mindful of the source checks, formatting, and structure of the git commit message we abide by. In particular, if there is a JIRA issue, reference it in the first line of your commit message, for example:

Once you have become sufficiently involved with the community, we may well invite you to be a committer. See How do I become a committer for more details.