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+# Contributing to the Yunohost core
+
+You wish to implement a new feature in the Yunohost core, but don't know how to
+proceed ? This guide takes you through the various steps of the development and
+contribution process. 
+
+## Setting up a development environment
+
+- **Use [ynh-dev](https://github.com/YunoHost/ynh-dev)** (see the README) to
+  setup a development environment - locally in a virtual machine, or on a VPS.
+  This will setup a working Yunohost instance, using git repositories and
+  symlinks. That way, you will be able to edit files, test your changes, commit
+  stuff and push/pull directly from your development environment.
+
+- Implement and test your feature. Depending on what you want to develop, you
+  will want to :
+   - **Python/CLI core** : work in `/vagrant/yunohost/`, i.e. the Python/CLI core
+   - **Web administration interface** : work in `/vagrant/yunohost-admin/`
+   - You can also work on the other projects (SSOwat, moulinette) in similar ways
+
+## Developping on the Yunohost Python/CLI core
+
+- Work in `/vagrant/yunohost/`
+
+- The actionsmap file (`data/actionsmap/yunohost.yml`) defines the various
+  categories, actions and arguments of the yunohost CLI. Define how you want
+  users to use your feature, and add/edit the corresponding categories, actions
+  and arguments. For example in `yunohost domain add some.domain.tld`, the
+  category is `domain`, the action is `add`, and `some.domain.tld` is an
+  argument.
+
+- Moulinette will automatically map commands in the actionsmap to python
+  functions (and their arguments) located in `src/yunohost/`. For example, typing
+  `yunohost domain add some.domain.tld` will call the function
+  `domain_add(domainName)` in `domain.py`, with the argument `domainName` equal
+  to `"some.domain.tld"`.
+
+#### Helpers / coding style
+
+- To handle exceptions, you should raise some `MoulinetteError()`
+
+- To help with internationalizing the messages, use `m18n.n('some-message-id')`
+  and put your string in `locales/en.json`. You can also put arguments and use
+  them in the string with `{{some-argument:s}}`. Don't edit other locales files,
+  only the en.json !
+
+- Yunohost tries to follow the [pep8](http://pep8.org/) coding style. Tools
+  exist to automatically check conformity.
+
+- Name of "private" functions should start with a `_`
+
+#### Don't forget
+
+- (Might not be necessary anymore) Each time you edit the actionsmap, you should
+  force the refresh of the cache with `rm
+  /var/cache/moulinette/actionsmap/yunohost.pkl`
+
+## Adding stuff to the Yunohost web administration interface
+
+- Work in `/vagrant/yunohost-admin/src/`
+
+- Make sure the web admin interface of your development environment works, by
+  opening `https://domain.tld/yunohost/admin`. If not, run `npm install` and
+  `npm run build` in `yunohost-admin/src/`. [Not sure about this, to be checked]
+
+- The web interface uses the API to interact with Yunohost. The API
+  commands/requests are also defined via the actionsmap. For instance, accessing
+  the page ```https://domain.tld/yunohost/api/users``` corresponds to a `GET
+  /domains` requests on the Yunohost API. It is mapped to the function
+  `user_list()`. Accessing the URL should display the json returned by this
+  function. 'GET' requests are typically meant to ask information to the server.
+  'POST' requests are meant to ask the server to edit/change some information,
+  or to execute some actions.
+
+- `js/yunohost/controllers` contains the javascript parts,
+  and define which requests to make to the API when loading a specific page of
+  the interface, and how to process the data to generate the page, using
+  templates.
+
+- `views` contains the various templates for the pages of the interface. In the
+  template, data coming from the javascript part can be used with the syntax
+  `{{some-variable}}`, which will be replaced when building/accessing the page.
+  It is also possible to have conditions using the
+  [handlebars.js](http://handlebarsjs.com) syntax : ```{{#if
+  some-variable}}<p>Some conditionnal HTML code here !</p>{{/if}}```
+
+- For internationalized strings, use `y18n.t('some-string-code')` in the
+  javascript, or `{{t 'some-string-code'}}` in the HTML template, and put your
+  string in `locales/en.json`. Don't edit other locales files, only the 
+  en.json !
+
+#### Don't forget
+
+- Each time you edit the actionsmap, you should restart the yunohost-api :
+  ```service yunohost-api restart```
+  (You'll need to retype your admin password in the web interface)
+
+- Each time you edit something in the `js` folder, you should re-build with npm :
+  ```npm run build-dev``` 
+  and clear the cache of your browser.
+
+- Each time you edit something in the `views` folder, you should clear the cache
+  of your browser
+
+
+## Your feature is working and you want it to be integrated in Yunohost
+
+- Fork the relevant repo on Github, and commit stuff to a new branch with a name
+  like `enh-name-of-feature`.
+
+- Once you're ready, open a Pull Request on Github
+
+- After reviewing, testing and validation by other contributors, your branch
+should be merged in `testing` (?) !
+
+