Send TCP traffic to the ingress's namespace with Nginx Ingress - kubernetes

Question

I'm using an Nginx Ingress controller to open connections to a postgres database with the --tcp-services-configmap=k8s-ingress/k8s-ingress-tcp flag. That configmap looks like
apiVersion: v1
data:
"5432": namespace-a/the-postgres-svc:5432
kind: ConfigMap
This portion works perfectly, however I would like to open up another service on the same port, 5432 to namespace-b/the-postgres-svc:5432.
Is there any way to have the namespace selected be based on the namespace from the ingress resource? Since the data key would be identical if I were to just add that record to the after the "namespace-a" record I am not able to just append to the configmap data.
Thanks!

Answer 1

So you would like to have services on the same port in different namespaces.
I have found interesting step-by-step tutorial for this approach.
Firstly you should create two namespaces:
apiVersion: v1
kind: Namespace
metadata:
name: namespace-a
apiVersion: v1
kind: Namespace
metadata:
name: namespace-b
Than have your services and deployment definition, where the difference is between name and namespace fields:
apiVersion: v1
kind: Service
metadata:
labels:
run: nginx
name: namespacea-nginx
namespace: namespace-a
spec:
ports:
- port: 5432
protocol: TCP
targetPort: 5432
selector:
run: nginx
apiVersion: v1
kind: Service
metadata:
labels:
run: nginx
name: namespaceb-nginx
namespace: namespace-b
spec:
ports:
- port: 5432
protocol: TCP
targetPort: 5432
selector:
run: nginx
Deployment files:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
labels:
run: nginx
name: nginx
namespace: namespace-a
spec:
...
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
labels:
run: nginx
name: nginx
namespace: namespace-b
spec:
...
And finally, Ingress files definitions:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-ingress
namespace: namespace-a
annotations:
kubernetes.io/ingress.class: nginx
spec:
rules:
- host: namespacea.com
http:
paths:
- backend:
serviceName: namespacea-nginx
servicePort: 5432
path: /
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-ingress
namespace: namespace-b
annotations:
kubernetes.io/ingress.class: nginx
spec:
rules:
- host: namespaceb.com
http:
paths:
- backend:
serviceName: namespaceb-nginx
servicePort: 5432
path: /