service.yaml

# A service handles request either coming from inside the Kubernetes cluster
# from one pod to another or outside the cluster. They define how requests
# should be routed/handled. Service is usually a load balancer, though there
# are many different types of service that we can configure.

# Another term that is associated with exposing our application is ingress,
# we won't be using/discussing it here, as it's generally used for exposing
# multiple services under the same IP address, which we technically don't have/need
# for this application.
# https://medium.com/google-cloud/kubernetes-nodeport-vs-loadbalancer-vs-ingress-when-should-i-use-what-922f010849e0

# 1. we create a service, and it's going to be applied to any pods that has
# the name fastapi-model (the selector section). `selector` labels are key-value
# pairs specified/used by the users to select a set of objects. We have the
# flexibility to develop our own conventions.

# 2. there're many different options for configuring ports, see comments
apiVersion: v1
kind: Service
metadata:
    name: fastapi-model-service
spec:
    selector:
        app: fastapi-model
    type: LoadBalancer
    ports:
        - protocol: TCP
          # this port is accessible within the cluster,
          # i.e. inter-communications between the pods, so if a pod inside
          # the cluster wants to talk to this application
          port: 80
          # port to forward to inside the pod
          targetPort: 80