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Thanks for helping us to make KSQL even better!

If you have any questions about how to contribute, either create a GH issue or ask your question in the #ksql channel in our public Confluent Community Slack (account registration is free and self-service).

Developing KSQL

Building and running KSQL locally

To build and run KSQL locally, run the following commands:

$ mvn clean package -DskipTests
$ ./bin/ksql-server-start -daemon config/
$ ./bin/ksql

This will start the KSQL server in the background and the KSQL CLI in the foreground.

If you would rather have the KSQL server logs spool to the console, then drop the -daemon switch, and start the CLI in a second console.

Testing changes locally

To build and test changes locally, run the following commands:

$ mvn clean install checkstyle:check integration-test

How to Contribute

Reporting Bugs and Issues

Report bugs and issues by creating a new GitHub issue. Prior to creating an issue, please search through existing issues so that you are not creating duplicate ones.

Guidelines for Contributing Code, Examples, Documentation

When submitting a pull request (PR), use the following guidelines:

  • Follow the style guide below
  • Add/update documentation appropriately for the change you are making.
  • If you are introducing a new feature you may want to first submit your idea by creating a new GitHub issue to solicit feedback.
  • Non-trivial changes should include unit tests covering the new functionality and potentially function tests.
  • Bug fixes should include a unit test or integration test reproducing the issue and potentially function tests.
  • Try to keep pull requests short and submit separate ones for unrelated features, but feel free to combine simple bugfixes/tests into one pull request.
  • Keep the number of commits small and combine commits for related changes.
  • Each commit should compile on its own and ideally pass tests.
  • Keep formatting changes in separate commits to make code reviews easier and distinguish them from actual code changes.

Code Style

The project uses [GoogeStyle][] code formating. You can install this code style into your IDE to make things more automatic:

In addition, the project also uses final fields, parameters and local variables for new code submissions. IntelliJ's code generation can be configured to do this automatically:

 Preferences -> Code Style -> Java -> Code Generation

 - Make generated local variables final
 - Make generated parameters final

Static code analysis

The project build runs checkstyle and findbugs as part of the build.

You can set up IntelliJ for CheckStyle. First install the CheckStyle IDEA plugin, then:

IntelliJ->Preferences→Other Settings→CheckStyle

- Add a new configurations file using the '+' button:
   Description: Confluent Checks
   Ignore invalid certs: true

- (Optional) Make the new configuration active.

- Highlight the newly added 'Confluent Checks' and click the edit button (pencil icon).

- Set properties to match the `checkstyle/` file in the repo.

'Confluent Checks' will now be available in the CheckStyle tool window in the IDE and will auto-highlight issues in the code editor.

GitHub Workflow

  1. Fork the confluentinc/ksql repository into your GitHub account:

  2. Clone your fork of the GitHub repository, replacing <username> with your GitHub username.

    Use ssh (recommended):

    git clone<username>/ksql.git

    Or https:

    git clone<username>/ksql.git
  3. Add a remote to keep up with upstream changes.

    git remote add upstream

    If you already have a copy, fetch upstream changes.

    git fetch upstream
  4. Create a feature branch to work in.

    git checkout -b feature-xxx remotes/upstream/master
  5. Work in your feature branch.

    git commit -a
  6. Periodically rebase your changes

    git pull --rebase
  7. When done, combine ("squash") related commits into a single one

    git rebase -i upstream/master

    This will open your editor and allow you to re-order commits and merge them:

    • Re-order the lines to change commit order (to the extent possible without creating conflicts)
    • Prefix commits using s (squash) or f (fixup) to merge extraneous commits.
  8. Submit a pull-request

    git push origin feature-xxx

    Go to your fork main page<username>/ksql

    If you recently pushed your changes GitHub will automatically pop up a Compare & pull request button for any branches you recently pushed to. If you click that button it will automatically offer you to submit your pull-request to the confluentinc/ksql repository.

    • Give your pull-request a meaningful title.
    • In the description, explain your changes and the problem they are solving.
  9. Addressing code review comments

    Repeat steps 5. through 7. to address any code review comments and rebase your changes if necessary.

    Push your updated changes to update the pull request

    git push origin [--force] feature-xxx

    --force may be necessary to overwrite your existing pull request in case your commit history was changed when performing the rebase.

    Note: Be careful when using --force since you may lose data if you are not careful.

    git push origin --force feature-xxx
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