In case of questions about the contribution process or for discussion of specific issues please visit the [akka/dev gitter chat](https://gitter.im/akka/dev).
These guidelines are meant to be a living document that should be changed and adapted as needed. We encourage changes that make it easier to achieve our goals in an efficient way.
This is the process for committing code into master. There are of course exceptions to these rules, for example minor changes to comments and documentation, fixing a broken build etc.
1. There is a ticket for your work in the project's issue tracker. If not, create it first.
2. The ticket has been scheduled for the current milestone.
3. The ticket is estimated by the team.
4. The ticket have been discussed and prioritized by the team.
3. You should always perform your work in a Git feature branch. The branch should be given a descriptive name that explains its intent. Some teams also like adding the ticket number and/or the [GitHub](http://github.com) user ID to the branch name, these details is up to each of the individual teams.
4. When the feature or fix is completed you should open a [Pull Request](https://help.github.com/articles/using-pull-requests) on GitHub.
5. The Pull Request should be reviewed by other maintainers (as many as feasible/practical). Note that the maintainers can consist of outside contributors, both within and outside Typesafe. Outside contributors (for example from EPFL or independent committers) are encouraged to participate in the review process, it is not a closed process.
6. After the review you should fix the issues as needed (pushing a new commit for new review etc.), iterating until the reviewers give their thumbs up.
When the branch conflicts with its merge target (either by way of git merge conflict or failing CI tests), do **not** merge the target branch into your feature branch. Instead rebase your branch onto the target branch. Merges complicate the git history, especially for the squashing which is necessary later (see below).
7. Once the code has passed review the Pull Request can be merged into the master branch. For this purpose the commits which were added on the feature branch should be squashed into a single commit. This can be done using the command `git rebase -i master` (or the appropriate target branch), `pick`ing the first commit and `squash`ing all following ones.
Also make sure that the commit message conforms to the syntax specified below.
8. If the code change needs to be applied to other branches as well, create pull requests against those branches which contain the change after rebasing it onto the respective branch and await successful verification by the continuous integration infrastructure; then merge those pull requests.
Please mark these pull requests with `(for validation)` in the title to make the purpose clear in the pull request list.
9. Once everything is said and done, associate the ticket with the “earliest” release milestone (i.e. if back-ported so that it will be in release x.y.z, find the relevant milestone for that release) and close it.
2. The Notices file for the project includes the Typesafe copyright notice and no other files contain copyright notices. See http://www.apache.org/legal/src-headers.html for instructions for managing this approach for copyrights.
- Use a form of ``Copyright (C) 2011-2016 Typesafe Inc. <http://www.typesafe.com>``, where the start year is when the project or file was first created and the end year is the last time the project or file was modified.
- Do not use ``@author`` tags since it does not encourage [Collective Code Ownership](http://www.extremeprogramming.org/rules/collective.html). However, each project should make sure that the contributors gets the credit they deserve—in a text file or page on the project website and in the release notes etc.
If these requirements are not met then the code should **not** be merged into master, or even reviewed - regardless of how good or important it is. No exceptions.
Whether or not a pull request (or parts of it) shall be back- or forward-ported will be discussed on the pull request discussion page, it shall therefore not be part of the commit messages. If desired the intent can be expressed in the pull request description.
Each project should be configured to use a continuous integration (CI) tool (i.e. a build server à la Jenkins). Typesafe has a [Jenkins server farm](https://jenkins.akka.io/) that can be used. The CI tool should, on each push to master, build the **full** distribution and run **all** tests, and if something fails it should email out a notification with the failure report to the committer and the core team. The CI tool should also be used in conjunction with a Pull Request validator (discussed below).
All documentation is preferred to be in Typesafe's standard documentation format [reStructuredText](http://doc.akka.io/docs/akka/snapshot/dev/documentation.html) compiled using Typesafe's customized [Sphinx](http://sphinx.pocoo.org/) based documentation generation system, which among other things allows all code in the documentation to be externalized into compiled files and imported into the documentation.
For more info, or for a starting point for new projects, look at the [Typesafe Documentation Template project](https://github.com/typesafehub/doc-template).
For larger projects that have invested a lot of time and resources into their current documentation and samples scheme (like for example Play), it is understandable that it will take some time to migrate to this new model. In these cases someone from the project needs to take the responsibility of manual QA and verifier for the documentation and samples.
All the external runtime dependencies for the project, including transitive dependencies, must have an open source license that is equal to, or compatible with, [Apache 2](http://www.apache.org/licenses/LICENSE-2.0).
Which licenses are compatible with Apache 2 are defined in [this doc](http://www.apache.org/legal/3party.html#category-a), where you can see that the licenses that are listed under ``Category A`` automatically compatible with Apache 2, while the ones listed under ``Category B`` needs additional action:
> Each license in this category requires some degree of [reciprocity](http://www.apache.org/legal/3party.html#define-reciprocal); therefore, additional action must be taken in order to minimize the chance that a user of an Apache product will create a derivative work of a reciprocally-licensed portion of an Apache product without being aware of the applicable requirements.
Each project must also create and maintain a list of all dependencies and their licenses, including all their transitive dependencies. This can be done either in the documentation or in the build file next to each dependency.
It is ok to work on a public feature branch in the GitHub repository. Something that can sometimes be useful for early feedback etc. If so, then it is preferable to name the branch accordingly. This can be done by either prefixing the name with ``wip-`` as in ‘Work In Progress’, or using hierarchical names like ``wip/..``, ``feature/..`` or ``topic/..``. Either way is fine as long as it is clear that it is work in progress and not ready for merge. This work can temporarily have a lower standard. However, to be merged into master it will have to go through the regular process outlined above, with Pull Request, review etc..
Also, to facilitate both well-formed commits and working together, the ``wip`` and ``feature``/``topic`` identifiers also have special meaning. Any branch labelled with ``wip`` is considered “git-unstable” and may be rebased and have its history rewritten. Any branch with ``feature``/``topic`` in the name is considered “stable” enough for others to depend on when a group is working on a feature.
## Creating Commits And Writing Commit Messages
Follow these guidelines when creating public commits and writing commit messages.
1. If your work spans multiple local commits (for example; if you do safe point commits while working in a feature branch or work in a branch for a long time doing merges/rebases etc.) then please do not commit it all but rewrite the history by squashing the commits into a single big commit which you write a good commit message for (like discussed in the following sections). For more info read this article: [Git Workflow](http://sandofsky.com/blog/git-workflow.html). Every commit should be able to be used in isolation, cherry picked etc.
2. First line should be a descriptive sentence what the commit is doing, including the ticket number. It should be possible to fully understand what the commit does—but not necessarily how it does it—by just reading this single line. We follow the “imperative present tense” style for commit messages ([more info here](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html)).
From now on, whenever new commits are pushed to the Pull Request, a validation job will be automaticaly started and the results of the validation posted to the Pull Request.
