How can my services communicate with each other in a kubernetes deployment? - kubernetes

Question

Part of my deployment looks like this
client -- main service __ service 1
|__ service 2
NOTE: Each of these 4 services is a container and I'm trying to do this where each is in it's own Pod (without using multi container pod)
Where main service must make a call to service 1, get results then send those results to service 2, get that result and send it back to the web client
main service operates in this order
receive request from web client pot :80
make request to http://localhost:8000 (service 1)
make request to http://localhost:8001 (service 2)
merge results
respond to web client with result
My deployments for service 1 and 2 look like this
SERVICE 1
apiVersion: v1
kind: Service
metadata:
name: serviceone
spec:
selector:
run: serviceone
ports:
- port: 80
targetPort: 5050
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: serviceone-deployment
spec:
replicas: 1
selector:
matchLabels:
run: serviceone
template:
metadata:
labels:
run: serviceone
spec:
containers:
- name: serviceone
image: test.azurecr.io/serviceone:v1
imagePullPolicy: IfNotPresent
ports:
- containerPort: 5050
SERVICE 2
apiVersion: v1
kind: Service
metadata:
name: servicetwo
spec:
selector:
run: servicetwo
ports:
- port: 80
targetPort: 5000
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: servicetwo-deployment
spec:
replicas: 1
selector:
matchLabels:
run: servicetwo
template:
metadata:
labels:
run: servicetwo
spec:
containers:
- name: servicetwo
image: test.azurecr.io/servicetwo:v1
imagePullPolicy: IfNotPresent
ports:
- containerPort: 5000
But I don't know what the service and deployment would look like for the main service that has to make request to two other services.
EDIT: This is my attempt at the service/deployment for main service
apiVersion: v1
kind: Service
metadata:
name: mainservice
spec:
selector:
run: mainservice
ports:
- port: 80 # incoming traffic from web client pod
targetPort: 80 # traffic goes to container port 80
selector:
run: serviceone
ports:
- port: ?
targetPort: 8000 # the port the container is hardcoded to send traffic to service one
selector:
run: servicetwo
ports:
- port: ?
targetPort: 8001 # the port the container is hardcoded to send traffic to service two
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: mainservice-deployment
spec:
replicas: 1
selector:
matchLabels:
run: mainservice
template:
metadata:
labels:
run: mainservice
spec:
containers:
- name: mainservice
image: test.azurecr.io/mainservice:v1
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
EDIT 2: alternate attempt at the service after finding this https://kubernetes.io/docs/concepts/services-networking/service/#multi-port-services
apiVersion: v1
kind: Service
metadata:
name: mainservice
spec:
selector:
run: mainservice
ports:
- name: incoming
port: 80 # incoming traffic from web client pod
targetPort: 80 # traffic goes to container port 80
- name: s1
port: 8080
targetPort: 8000 # the port the container is hardcoded to send traffic to service one
- name: s2
port: 8081
targetPort: 8001 # the port the container is hardcoded to send traffic to service two

Answer 1

The main service doesn't need to know anything about the services it calls other than their names. Simply access those services using the name of the Service, i.e. service1 and service2 (http://service1:80) and the requests will be forwarded to the correct pod.
Reference: https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/