Merge branch 'gokmengoksel/gitlab-ce-koding' into 'master'

Koding Integration

## What does this MR do?

Will provide Koding integration with GitLab services. Forked from !4914.

## Are there points in the code the reviewer needs to double check?
I've introduced new layouts which might not be necessary, first time contributor. 

## Why was this MR needed?
We're planning to ship Koding with GitLab.

## What are the relevant issue numbers?
#12759 #14698 

## Screenshots (if relevant)

### Screencasts

http://recordit.co/BDMbhwgxPD
http://recordit.co/By0qiz1ClC

### Enable Koding in Application Settings

![image](/uploads/73a69421105c03aa2b0b47e2617d3fbc/image.png)

### Koding Dashboard
![image](/uploads/6c7dda34792280c0e4791e36af4eba11/image.png)

### Set up Koding Stack
1 - ![image](/uploads/d5c2b93f8e61b5cbffdb06f0267d485f/image.png)
2 - ![image](/uploads/44d9a9b574b8ac0c5eb553fb9653d5da/image.png)

### Run on Koding on Project Page

![image](/uploads/7d2b46221009074ffff75d66d5a1a555/image.png)

### Run in IDE on Merge Requests
![image](/uploads/65eed90c34c34b5fe7ad29ef9c717640/image.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5909

1 files changed, 122 insertions, 0 deletions

diff --git a/doc/integration/koding-usage.md b/doc/integration/koding-usage.md
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+# Koding & GitLab
+
+This document will guide you through using Koding integration on GitLab in
+detail. For configuring and installing please follow [this](koding.md) guide.
+
+You can use Koding integration to run and develop your projects on GitLab. This
+will allow you and the users to test your project without leaving the browser.
+Koding handles projects as stacks which are basic recipes to define your
+environment for your project. With this integration you can automatically
+create a proper stack template for your projects. Currently auto-generated
+stack templates are designed to work with AWS which requires a valid AWS
+credential to be able to use these stacks. You can find more information about
+stacks and the other providers that you can use on Koding from
+[here](https://www.koding.com/docs).
+
+
+# Enable Integration
+
+You can enable Koding integration by providing the running Koding instance URL
+in Application Settings;
+
+ - Open **Admin area > Settings** (`/admin/application_settings`).
+
+![Enable Koding](help/integration/img/koding_enable-koding.png)
+
+Once enabled you will see `Koding` link on your sidebar which leads you to
+Koding Landing page
+
+![Koding Landing](help/integration/img/koding_landing.png)
+
+You can navigate to running Koding instance from here. For more information and
+details about configuring integration please follow [this](koding.md) guide.
+
+
+# Set up Koding on Projects
+
+Once it's enabled, you will see some integration buttons on Project pages,
+Merge Requests etc. To get started working on a specific project you first need
+to create a `.koding.yml` file under your project root. You can easily do that
+by using `Set Up Koding` button which will be visible on every project's
+landing page;
+
+![Set Up Koding](help/integration/img/koding_set-up-ide.png)
+
+Once you click this will open a New File page on GitLab with auto-generated
+`.koding.yml` content based on your server and repository configuration.
+
+![Commit .koding.yml](help/integration/img/koding_commit-koding.yml.png)
+
+
+# Run a project on Koding
+
+If there is `.koding.yml` exists in your project root, you will see
+`Run in IDE (Koding)` button in your project landing page. You can initiate the
+process from here.
+
+![Run on Koding](help/integration/img/koding_run-in-ide.png)
+
+This will open Koding defined in the settings in a new window and will start
+importing the project's stack file;
+
+![Import Stack](help/integration/img/koding_stack-import.png)
+
+You should see the details of your repository imported into your Koding
+instance. Once it's completed it will lead you to the Stack Editor and from
+there you can start using your new stack integrated with your project on your
+GitLab instance. For details about what's next you can follow
+[this](https://www.koding.com/docs/creating-an-aws-stack) guide from 8. step.
+
+Once stack initialized you will see the `README.md` content from your project
+in `Stack Build` wizard, this wizard will let you to build the stack and import
+your project into it. **Once it's completed it will automatically open the
+related vm instead of importing from scratch**
+
+![Stack Building](help/integration/img/koding_start-build.png)
+
+This will take time depending on the required environment.
+
+![Stack Building in Progress](help/integration/img/koding_build-in-progress.png)
+
+It usually takes ~4 min. to make it ready with a `t2.nano` instance on given
+AWS region. (`t2.nano` is default vm type on auto-generated stack template
+which can be manually changed)
+
+![Stack Building Success](help/integration/img/koding_build-success.png)
+
+You can check out the `Build Logs` from this success modal as well;
+
+![Stack Build Logs](help/integration/img/koding_build-logs.png)
+
+You can now `Start Coding`!
+
+![Edit On IDE](help/integration/img/koding_edit-on-ide.png)
+
+
+# Try a Merge Request on IDE
+
+It's also possible to try a change on IDE before merging it. This flow only
+enabled if the target project has `.koding.yml` in it's target branch. You
+should see the alternative version of `Run in IDE (Koding)` button in merge
+request pages as well;
+
+![Run in IDE on MR](help/integration/img/koding_run-mr-in-ide.png)
+
+This will again take you to Koding with proper arguments passed, which will
+allow Koding to modify the stack template provided by target branch. You can
+see the difference;
+
+![Different Branch for MR](help/integration/img/koding_different-stack-on-mr-try.png)
+
+The flow for the branch stack is also same with the regular project flow.
+
+
+# Open GitLab from Koding
+
+Since stacks generated with import flow defined in previous steps, they have
+information about the repository they are belonging to. By using this
+information you can access to related GitLab page from stacks on your sidebar
+on Koding.
+
+![Open GitLab from Koding](help/integration/img/koding_open-gitlab-from-koding.png)
+