Contributing to the Development of openHAB

The Repositories

Note that the openHAB distribution repository does not contain any source code, but it rather aggregates features from different repos:

  • Eclipse SmartHome Framework: This repo holds the major parts of the core functionality.
  • openHAB 2 Core: This repo contains a few small bundles that are not part of Eclipse SmartHome, but required for the openHAB runtime. This e.g. contains a compatibility layer for supporting openHAB 1 add-ons.
  • openHAB 2 Add-ons: Add-ons of openHAB that use the Eclipse SmartHome APIs can be found within this repository. They cannot be used with an openHAB 1.x runtime, since they provide features that the old runtime does not support.
  • openHAB 1 Add-ons: Add-ons developed for openHAB 1.x. Most of them are working smoothly on the openHAB 2 runtime and thus they are packaged within the distribution.
  • Eclipse SmartHome Extensions: Since openHAB uses the Eclipse SmartHome framework, it is automatically compatible with all extensions that are available for it and maintained within the Eclipse SmartHome repository. These are usually high-quality extensions that might be even used in commercial products.

Contribution Guidelines

Pull Requests are Always Welcome

We are always thrilled to receive pull requests, and do our best to process them as fast as possible. Not sure if that typo is worth a pull request? Do it! We will appreciate it.

If your pull request is not accepted on the first try, don’t be discouraged! If there’s a problem with the implementation, hopefully you received feedback on what to improve.

We’re trying very hard to keep openHAB lean and focused. We don’t want it to do everything for everybody. This means that we might decide against incorporating a new feature. However, there might be a way to implement that feature on top of openHAB.

Discuss your Design on the Mailing List

We recommend discussing your plans in the discussion forum before starting to code - especially for more ambitious contributions. This gives other contributors a chance to point you in the right direction, give feedback on your design, and maybe point out if someone else is working on the same thing.

Create Issues…

Any significant improvement should be documented as a GitHub issue in the appropriate repository before anybody starts working on it.

…but Check for Existing Issues First!

Please take a moment to check that an issue doesn’t already exist documenting your bug report or improvement proposal. If it does, it never hurts to add a quick “+1” or “I have this problem too”. This will help prioritize the most common problems and requests.

Conventions

Fork the repo and make changes on your fork in a feature branch:

  • If it’s a bugfix branch, name it XXX-something where XXX is the number of the issue
  • If it’s a feature branch, create an enhancement issue to announce your intentions, and name it XXX-something where XXX is the number of the issue.

Submit unit tests for your changes. openHAB has a great test framework built in; use it! Take a look at existing tests for inspiration. Run the full test suite on your branch before submitting a pull request.

Update the documentation when creating or modifying features. Test your documentation changes for clarity, concision, and correctness, as well as a clean documentation build.

Write clean code. Universally formatted code promotes ease of writing, reading, and maintenance.

Pull requests descriptions should be as clear as possible and include a reference to all the issues that they address.

Pull requests must not contain commits from other users or branches.

Commit messages must start with a capitalized and short summary (max. 50 chars) written in the imperative, followed by an optional, more detailed explanatory text which is separated from the summary by an empty line.

Code review comments may be added to your pull request. Discuss, then make the suggested modifications and push additional commits to your feature branch. Be sure to post a comment after pushing. The new commits will show up in the pull request automatically, but the reviewers will not be notified unless you comment.

Before the pull request is merged, make sure that you squash your commits into logical units of work using git rebase -i and git push -f. After every commit the test suite should be passing. Include documentation changes in the same commit so that a revert would remove all traces of the feature or fix.

Commits that fix or close an issue should include a reference like Closes #XXX or Fixes #XXX, which will automatically close the issue when merged.

Merge Approval

openHAB maintainers use the Github review feature to indicate acceptance.

A change requires approval from an absolute majority of the maintainers of each component affected. For example, if a change affects addons/ and features/, it needs an absolute majority from the maintainers of addons/ AND, separately, an absolute majority of the maintainers of features/.

Sign your Work

The sign-off is a simple line at the end of the explanation for the patch, which certifies that you wrote it or otherwise have the right to pass it on as an open-source patch. The rules are pretty simple: if you can certify the below (from developercertificate.org):

Developer Certificate of Origin
Version 1.1

Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
660 York Street, Suite 102,
San Francisco, CA 94110 USA

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

then you just add a line to every git commit message:

Signed-off-by: Joe Smith <[email protected]> (github: github_handle)

using your real name (sorry, no pseudonyms or anonymous contributions.)

If your commit contains code from others as well, please ensure that they certify the DCO as well and add them with an “Also-By” line to your commit message:

Also-by: Ted Nerd <[email protected]> (github: github_handle_ted)
Also-by: Sue Walker <[email protected]> (github: github_handle_sue)
Signed-off-by: Joe Smith <[email protected]> (github: github_handle_joe)

Small Patch Exception

There are several exceptions to the signing requirement. Currently these are:

  • Your patch fixes spelling or grammar errors.
  • Your patch is a single line change to documentation.

How can I Become a Maintainer?

  • Step 1: learn the component inside out
  • Step 2: make yourself useful by contributing code, bugfixes, support etc.
  • Step 3: volunteer on [in the community] (https://community.openhab.org/)

Don’t forget: being a maintainer is a time investment. Make sure you will have time to make yourself available. You don’t have to be a maintainer to make a difference on the project!

Community Guidelines

We want to keep the openHAB community awesome, growing and collaborative. We need your help to keep it that way. To help with this we’ve come up with some general guidelines for the community as a whole:

  • Be nice: Be courteous, respectful and polite to fellow community members: no regional, racial, gender, or other abuse will be tolerated. We like nice people way better than mean ones!

  • Encourage diversity and participation: Make everyone in our community feel welcome, regardless of their background and the extent of their contributions, and do everything possible to encourage participation in our community.

  • Keep it legal: Basically, don’t get us in trouble. Share only content that you own, do not share private or sensitive information, and don’t break the law.

  • Stay on topic: Make sure that you are posting to the correct channel and avoid off-topic discussions. Remember when you update an issue or respond to an email you are potentially sending to a large number of people. Please consider this before you update. Also remember that nobody likes spam.