How to expose 80 port in kubernetes nginx controller - nginx

Question

I installed kubernete in several raspberry pi 4 without using cloud.
I follow tutorial to deploy mongodb and mongo express and I can
get inside the mongo express website using node port mode.
However, when I change to use nignx controller, it works when I
type ip address:port (192.168.1.194:30574 It is my master node ip and the port is where the ingress-nginx-controller expose) or domain:port (mymongo.com:30574).
But if I just use domain name (mymongo.com) without port, it cannot get inside the website. Do I miss something? Thank you!
Here is my yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: mongo-express-ingress
spec:
rules:
- host: "mymongo.com"
- http:
paths:
- pathType: Prefix
path: "/"
backend:
service:
name: mongo-express-service
port:
number: 8081
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: mongo-express
labels:
app: mongo-express
spec:
replicas: 1
selector:
matchLabels:
app: mongo-express
template:
metadata:
labels:
app: mongo-express
spec:
containers:
- name: mongo-express
image: mongo-express
ports:
- containerPort: 8081
env:
- name: ME_CONFIG_MONGODB_ADMINUSERNAME
valueFrom:
secretKeyRef:
name: mongodb-secret
key: mongo-root-username
- name: ME_CONFIG_MONGODB_ADMINPASSWORD
valueFrom:
secretKeyRef:
name: mongodb-secret
key: mongo-root-password
- name: ME_CONFIG_MONGODB_SERVER
valueFrom:
configMapKeyRef:
name: mongodb-configmap
key: database_url
---
apiVersion: v1
kind: Service
metadata:
name: mongo-express-service
spec:
selector:
app: mongo-express
ports:
- protocol: TCP
port: 8081
targetPort: 8081
ubuntu#master:~/k8s-config$ kubectl get services --all-namespaces
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
default kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8d
default mongo-express-service ClusterIP 10.107.95.131 <none> 8081/TCP 6d19h
default mongodb-service ClusterIP 10.101.118.57 <none> 27017/TCP 6d19h
ingress-nginx ingress-nginx-controller NodePort 10.96.94.30 <none> 80:30574/TCP,443:31882/TCP 6d4h
ingress-nginx ingress-nginx-controller-admission ClusterIP 10.104.121.41 <none> 443/TCP 6d4h
kube-system kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 8d
kubernetes-dashboard dashboard-metrics-scraper ClusterIP 10.99.4.159 <none> 8000/TCP 6d22h
kubernetes-dashboard kubernetes-dashboard NodePort 10.98.92.238 <none> 443:31044/TCP

Answer 1

In your current configuration, it works as expected.
Your Nginx Ingress Controller is configured as NodePort Type
NodePort: Exposes the Service on each Node's IP at a static port (the NodePort). A ClusterIP Service, to which the NodePort Service routes, is automatically created. You'll be able to contact the NodePort Service, from outside the cluster, by requesting :.
So if you are using NodePort type, you will be able to connect only when you will specify <NodeIP:NodePort>, in your case mymongo.com:30574 (NodeIP: mymongo.com, NodePort: 30574).
If you would like to use only a domain, you would need to consider ServiceType as LoadBalancer.
LoadBalancer: Exposes the Service externally using a cloud provider's load balancer. NodePort and ClusterIP Services, to which the external load balancer routes, are automatically created.
To achieve that without using Cloud LoadBalancer you can use MetalLB solution.
Your current configuration is also described in Nginx Ingress Documentation as Over a NodePort Service.
You can also consider using host network solution as alternative for baremaetal solution.
In a setup where there is no external load balancer available but using NodePorts is not an option, one can configure ingress-nginx Pods to use the network of the host they run on instead of a dedicated network namespace. The benefit of this approach is that the NGINX Ingress controller can bind ports 80 and 443 directly to Kubernetes nodes' network interfaces, without the extra network translation imposed by NodePort Services.
template:
spec:
hostNetwork: true