To add your own gitlab runner, follow the steps below

• Create your runner, in EC2, Google, or any other cloud provider and have ssh access to it.
• Login to your runner from the previous step and install the gitlab-runner (there are various methods described here: https://docs.gitlab.com/runner/install/. We install using Gitlab’s repositories)
• Register the gitlab-runner by following the instructions here: https://docs.gitlab.com/runner/register/index.html . You would need to get the token for each project you want to register your runner with (Gitlab -> Settings -> CI/CD -> Runners -> Expand). You can use different executors for your running during the registration such as docker, shell etc.
• Go to your Gitlab project and find the runner you register above and enable it for the project. You should also add the tags: name_of_your_runner in your .gitlab-ci.yml file.