I have already added a Kubernetes cluster to my project in Gitlab. The cluster is hosted on AWS. This configuration works fine and I am able to deploy my apps. I want to add another Kubernetes cluster that is also hosted on AWS but in a different region to the same project. So far I am unable to find a way to add another cluster to the same project. Gitlab doesn't give me the option to add another cluster. Is it possible? And if it is possible how should I do it ?
Yes, it's possible, but only in Gitlab Enterprise Edition. Support for multiple Kubernetes clusters was introduced in Gitlab Premium/Ultimate 10.3.
With GitLab Premium, you can associate more than one Kubernetes clusters to your project. That way you can have different clusters for different environments, like dev, staging, production, etc.
Simply add another cluster, like you did the first time, and make sure to set an environment scope that will differentiate the new cluster with the rest.