How to get the config map as env variable to my auto deployed service

I am a newbie, just getting started with out of the box magic of auto devops by gitlab.

I have a very basic Golang Microservice that I am able to deploy - and it uses the default helm charts out of the box (creates namespace, service, deployment, docker registry management), and I provide my own Dockerfiles to build the docker image.

Question:

  1. How do I read an existing K8 ConfigMap entry as environment variable to the microservice without providing a custom helm chart? ConfigMap is created in a different namespace by some other process

  2. How do I override the namespace in which the Microservice should be deployed and not create a new namespace? I want multiple Microservices to be deployed into same namespace - I don’t want a different namespace for each repository.

Basically I don’t want to provide custom helm charts as I think if I provide custom chart then I will also need to do the complete setup of setting up docker registry on K8 cluster too - and I want to avoid that, I want to customize my application components, service type (I don’t want ClusterIP), change namespace, refer to configMap as environment variable - without managing the infrastructure of where image is being pulled from.

Thanks,
GB - newbie from Jenkins world.