# Getting started
This is a project to get started on the gitlab CI for compiling and testing code.

The master branch has a very rudimentary `.gitlab-ci.yml` file to build the project once.

You find the  branches `testlevel*`  with increasing test complexity in the script `.gitlab-ci.yml`.

Important things:
-  Explanations of the YAML syntax of the file **.gitlab-ci.yml** [found here](https://docs.gitlab.com/ce/ci/yaml)
- commits to not check: add `[CI skip]` in the commit message
- you can disable the email notifications under your personal notification settings in the gitlab


## Setup a local runner:
- Installation of a local runner [found here](https://docs.gitlab.com/runner/install/) be sure to install the version <= 1.11.4  
  `sudo apt-get install gitlab-ci-multi-runner=1.11.4`  
  since the mpcdf gitlab version is 8.17
- After installation of the runner, execute **in your home directory**
         gitlab-runner register  
  follow the steps with the url and token given on the `Settings->CI/CD pipeline` of your project on the gitlab page
- then start the runner
         gitlab-runner run  
  You should see the runner on the gitlab page  `Settings->CI/CD pipeline`

## Tags:
Tags only make sense if there are multiple runners. 
They allow to choose on which runner the job will be executed.

If the runner can run untagged jobs, you would not need tags, but we recommend to use at least one tag for the job, corresponding to the tag(s) of the runner. 

The tags are used to select a specific runner. Note the following:
1. Each job is assigned to only **one** runner!
1. If job has no tag
    - one runner must be configured to run untagged jobs 
1. Job has tags
    - **all** tags of a job **must match** a subset of the tags of **one** runner

Each job can have one or multiple tags, here an example:
```
job_1:
  stage: build
  tags:
    - tag1_runnerA
job_2:
  stage: build
  tags:
    - tag1_runnerB
job_3:
  stage: build
  tags:
    - tag1_runnerA
    - tag2_runnerA
```
- runner A  has the tags `tag1_runnerA` and `tag2_runnerA` ... and therefore runs  `job_1` and `job_3`
- runner B  has the tags `tag1_runnerB` and `tag2_runnerB` ... and therefore runs only `job_2`
- **Careful**, the tag list should contain only tags of **one** runner!
- **Careful**, different runners cannot have the same tag!