Merge branch 'ci-docs' into 'master'

Update CI quickstart guide

This includes fixes suggested by @axil 

Fixes #3260 

See merge request !1755

doc/ci/quick_start/README.md

 # Quick Start
 
-To start building projects with GitLab CI a few steps needs to be done.
+Starting from version 8.0, GitLab Continuous Integration (CI) is fully
+integrated into GitLab itself and is enabled by default on all projects.
 
-## 1. Install GitLab and CI
+This guide assumes that you:
 
-First you need to have a working GitLab and GitLab CI instance.
+- have a working GitLab instance of version 8.0 or higher or are using
+  [GitLab.com](https://gitlab.com/users/sign_in)
+- have a project in GitLab that you would like to use CI for
 
-You can omit this step if you use [GitLab.com](https://GitLab.com/).
+In brief, the steps needed to have a working CI can be summed up to:
 
-## 2. Create repository on GitLab
+1. Create a new project
+1. Add `.gitlab-ci.yml` to the git repository and push to GitLab
+1. Configure a Runner
 
-Once you login on your GitLab add a new repository where you will store your source code.
-Push your application to that repository.
+From there on, on every push to your git repository the build will be
+automagically started by the Runner and will appear under the project's
+`/builds` page.
 
-## 3. Add project to CI
+Now, let's break it down to pieces and work on solving the GitLab CI puzzle.
 
-The next part is to login to GitLab CI.
-Point your browser to the URL you have set GitLab or use [gitlab.com/ci](https://gitlab.com/ci/).
+## Creating a `.gitlab-ci.yml` file
 
-On the first screen you will see a list of GitLab's projects that you have access to:
+Before you create `.gitlab-ci.yml` let's first explain in brief what this is
+all about.
 
-![Projects](projects.png)
+### What is `.gitlab-ci.yml`
 
-Click **Add Project to CI**.
-This will create project in CI and authorize GitLab CI to fetch sources from GitLab.
+The `.gitlab-ci.yml` file is where you configure what CI does with your project.
+It lives in the root of your repository.
 
-> GitLab CI creates unique token that is used to configure GitLab CI service in GitLab.
-> This token allows to access GitLab's repository and configures GitLab to trigger GitLab CI webhook on **Push events** and **Tag push events**.
-> You can see that token by going to Project's Settings > Services > GitLab CI.
-> You will see there token, the same token is assigned in GitLab CI settings of project.
+On any push to your repository, GitLab will look for the `.gitlab-ci.yml`
+file and start builds on _Runners_ according to the contents of the file,
+for that commit.
 
-## 4. Create project's configuration - .gitlab-ci.yml
+Because `.gitlab-ci.yml` is in the repository, it is version controlled,
+old versions still build succesfully, forks can easily make use of CI,
+branches can have separate builds and you have a single source of truth for CI.
+You can read more about the reasons why we are using `.gitlab-ci.yml`
+[in our blog about it][blog-ci].
 
-The next: You have to define how your project will be built.
-GitLab CI uses [YAML](https://en.wikipedia.org/wiki/YAML) file to store build configuration.
-You need to create `.gitlab-ci.yml` in root directory of your repository:
+**Note:** `.gitlab-ci.yml` is a [YAML](https://en.wikipedia.org/wiki/YAML) file
+so you have to pay extra attention to the identation. Always use spaces, not
+tabs.
+
+### Creating a simple `.gitlab-ci.yml` file
+
+You need to create a file named `.gitlab-ci.yml` in the root directory of your
+repository. Below is an example for a Ruby on Rails project.
 
 ```yaml
 before_script:
-  - bundle install
+  - apt-get update -qq && apt-get install -y -qq sqlite3 libsqlite3-dev nodejs
+  - ruby -v
+  - which ruby
+  - gem install bundler --no-ri --no-rdoc
+  - bundle install --jobs $(nproc)  "${FLAGS[@]}"
 
 rspec:
   script:
@@ -49,71 +67,131 @@ rubocop:
     - bundle exec rubocop
 ```
 
-This is the simplest possible build configuration that will work for most Ruby applications:
-1. Define two jobs `rspec` and `rubocop` with two different commands to be executed.
-1. Before every job execute commands defined by `before_script`.
+This is the simplest possible build configuration that will work for most Ruby
+applications:
+
+1. Define two jobs `rspec` and `rubocop` (the names are arbitrary) with
+   different commands to be executed.
+1. Before every job, the commands defined by `before_script` are executed.
 
-The `.gitlab-ci.yml` defines set of jobs with constrains how and when they should be run.
-The jobs are defined as top-level elements with name and always have to contain the `script`.
-Jobs are used to create builds, which are then picked by [runners](../runners/README.md) and executed within environment of the runner.
-What is important that each job is run independently from each other. 
+The `.gitlab-ci.yml` file defines sets of jobs with constraints of how and when
+they should be run. The jobs are defined as top-level elements with a name (in
+our case `rspec` and `rubocop`) and always have to contain the `script` keyword.
+Jobs are used to create builds, which are then picked by
+[Runners](../runners/README.md) and executed within the environment of the Runner.
 
-For more information and complete `.gitlab-ci.yml` syntax, please check the [Configuring project (.gitlab-ci.yml)](../yaml/README.md).
+What is important is that each job is run independently from each other.
 
-## 5. Add file and push .gitlab-ci.yml to repository
+If you want to check whether your `.gitlab-ci.yml` file is valid, there is a
+Lint tool under the page `/ci/lint` of your GitLab instance. You can also find
+the link under **Settings > CI settings** in your project.
 
-Once you created `.gitlab-ci.yml` you should add it to git repository and push it to GitLab.
+For more information and a complete `.gitlab-ci.yml` syntax, please check
+[the documentation on .gitlab-ci.yml](../yaml/README.md).
+
+### Push `.gitlab-ci.yml` to GitLab
+
+Once you've created `.gitlab-ci.yml`, you should add it to your git repository
+and push it to GitLab.
 
 ```bash
 git add .gitlab-ci.yml
-git commit
+git commit -m "Add .gitlab-ci.yml"
 git push origin master
 ```
 
-If you refresh the project's page on GitLab CI you will notice a one new commit:
+Now if you go to the **Builds** page you will see that the builds are pending.
+
+You can also go to the **Commits** page and notice the little clock icon next
+to the commit SHA.
+
+![New commit pending](img/new_commit.png)
+
+Clicking on the clock icon you will be directed to the builds page for that
+specific commit.
+
+![Single commit builds page](img/single_commit_status_pending.png)
+
+Notice that there are two jobs pending which are named after what we wrote in
+`.gitlab-ci.yml`. The red triangle indicates that there is no Runner configured
+yet for these builds.
+
+The next step is to configure a Runner so that it picks the pending jobs.
+
+## Configuring a Runner
+
+In GitLab, Runners run the builds that you define in `.gitlab-ci.yml`.
+A Runner can be a virtual machine, a VPS, a bare-metal machine, a docker
+container or even a cluster of containers. GitLab and the Runners communicate
+through an API, so the only needed requirement is that the machine on which the
+Runner is configured to has Internet access.
+
+A Runner can be specific to a certain project or serve multiple projects in
+GitLab. If it serves all projects it's called a _Shared Runner_.
+
+Find more information about different Runners in the
+[Runners](../runners/README.md) documentation.
+
+You can find whether any Runners are assigned to your project by going to
+**Settings > Runners**. Setting up a Runner is easy and straightforward. The
+official Runner supported by GitLab is written in Go and can be found at
+<https://gitlab.com/gitlab-org/gitlab-ci-multi-runner>.
+
+In order to have a functional Runner you need to follow two steps:
+
+1. [Install it][runner-install]
+2. [Configure it](../runners/README.md#registering-a-specific-runner)
+
+Follow the links above to set up your own Runner or use a Shared Runner as
+described in the next section.
+
+For other types of unofficial Runners written in other languages, see the
+[instructions for the various GitLab Runners](https://about.gitlab.com/gitlab-ci/#gitlab-runner).
+
+Once the Runner has been set up, you should see it on the Runners page of your
+project, following **Settings > Runners**.
 
-![](new_commit.png)
+![Activated runners](img/runners_activated.png)
 
-However the commit has status **pending** which means that commit was not yet picked by runner.
+### Shared Runners
 
-## 6. Configure runner
+If you use [GitLab.com](https://gitlab.com/) you can use **Shared Runners**
+provided by GitLab Inc.
 
-In GitLab CI, Runners run your builds.
-A runner is a machine (can be virtual, bare-metal or VPS) that picks up builds through the coordinator API of GitLab CI.
+These are special virtual machines that run on GitLab's infrastructure and can
+build any project.
 
-A runner can be specific to a certain project or serve any project in GitLab CI.
-A runner that serves all projects is called a shared runner.
-More information about different runner types can be found in [Configuring runner](../runners/README.md).
+To enable **Shared Runners** you have to go to your project's
+**Settings > Runners** and click **Enable shared runners**.
 
-To check if you have runners assigned to your project go to **Runners**. You will find there information how to setup project specific runner:
+[Read more on Shared Runners](../runners/README.md).
 
-1. Install GitLab Runner software. Checkout the [GitLab Runner](https://about.gitlab.com/gitlab-ci/#gitlab-runner) section to install it.
-1. Specify following URL during runner setup: https://gitlab.com/ci/
-1. Use the following registration token during setup: TOKEN
+## Seeing the status of your build
 
-If you do it correctly your runner should be shown under **Runners activated for this project**:
+After configuring the Runner succesfully, you should see the status of your
+last commit change from _pending_ to either _running_, _success_ or _failed_.
 
-![](runners_activated.png)
+You can view all builds, by going to the **Builds** page in your project.
 
-### Shared runners
+![Commit status](img/builds_status.png)
 
-If you use [gitlab.com/ci](https://gitlab.com/ci/) you can use **Shared runners** provided by GitLab Inc.
-These are special virtual machines that are run on GitLab's infrastructure that can build any project.
-To enable **Shared runners** you have to go to **Runners** and click **Enable shared runners** for this project.
+By clicking on a Build ID, you will be able to see the log of that build.
+This is important to diagnose why a build failed or acted differently than
+you expected.
 
-## 7. Check status of commit
+![Build log](img/build_log.png)
 
-If everything went OK and you go to commit, the status of the commit should change from **pending** to either **running**, **success** or **failed**.
+You are also able to view the status of any commit in the various pages in
+GitLab, such as **Commits** and **Merge Requests**.
 
-![](commit_status.png)
+## Next steps
 
-You can click **Build ID** to view build log for specific job.
+Awesome! You started using CI in GitLab!
 
-## 8. Congratulations!
+Next you can look into doing more with the CI. Many people are using GitLab
+to package, containerize, test and deploy software.
 
-You managed to build your first project using GitLab CI.
-You may need to tune your `.gitlab-ci.yml` file to implement build plan for your project.
-A few examples how it can be done you can find on [Examples](../examples/README.md) page.
+Visit our various languages examples at <https://gitlab.com/groups/gitlab-examples>.
 
-GitLab CI also offers **the Lint** tool to verify validity of your `.gitlab-ci.yml` which can be useful to troubleshoot potential problems.
-The Lint is available from project's settings or by adding `/lint` to GitLab CI url.
+[runner-install]: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/tree/master#installation
+[blog-ci]: https://about.gitlab.com/2015/05/06/why-were-replacing-gitlab-ci-jobs-with-gitlab-ci-dot-yml/