I have a stateless app with 3 component say x,y,z in the same code base. Each component will be run by checking on the environment variable. I want to deploy it on Kubernetes on GCP using kind: Deployment yaml config with 3 replica pods. How can I make sure each component has a single dedicated pod to it? Can it be done on single deployment file?
As @Ivan Aracki mentioned in the comments, the best way would be distinguish each application component with appropriate deployment object in order to guarantee a Pod assignment here.
As I understand your requirements stated that you have three processes application code base inside one solution. Nit sure weather three components you mentioned are independent process components or just layer front end , service , DAL etc or even tiers e.g. typical 3 tier architecture application with front end web , API and backend tier but let's call three microservices or services for simplicity...
Whichever the case is , best practices of docker , kubernetes hosted microservices pattern recommends :
container per process small app (not monolethe)
though there can be multiple containers per pod, suggested is keep one per pod - you can possibly have three containers inside pod
You can have three pods one each for your component app provided these apps can be refactored into three separate independent processes.
Hope this helps.
As Ivan, suggested above, deploy three deployments one each for x, y and z.
You can use the same image for the three deployments, just pass different environment variable/value for each deployment to deploy specific component. You might have to build some logic in the container start up script to retrieve the value from the environment variable and start the desired component