ingress get the 503 feedback - kubernetes

Question

I want to config the ingress to work with my domain name.
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: app-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
tls:
- hosts:
- example.com
secretName: app-tls
rules:
- host: example.com
http:
paths:
- path: /my-api1(/|$)(.*)
backend:
serviceName: app1
servicePort: 80
- path: /my-api2
backend:
serviceName: app2
servicePort: 80
---
apiVersion: v1
kind: Service
metadata:
name: my-api
spec:
selector:
app: my-api
ports:
- name: app1
port: 3000
targetPort: 80
- name: app2
port: 4000
targetPort: 80
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: user-api
spec:
selector:
matchLabels:
app: user-api
template:
metadata:
labels:
app: user-api
spec:
hostNetwork: true
dnsPolicy: ClusterFirstWithHostNet
containers:
- name: app1
image: XXX
ports:
- name: app1
containerPort: 3000
- name: app2
image: XXX
ports:
- name: app2
containerPort: 4000
I can reach the app1 service by serverIP:3000(example. 172.16.111.211:3000/my-api1). But remotely it always return the 503 status code(curl https://example.com/my-api1).
# kubectl describe ingress app-ingress
Name: app-ingress
Namespace: default
Address: serverIP
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
TLS:
app-tls terminates example.com
Rules:
Host Path Backends
---- ---- --------
example.com
/my-api1(/|$)(.*) app1:80 (<error: endpoints "app1" not found>)
/my-api2 app2:80 (<error: endpoints "app2" not found>)

Answer 1

First thing is your service name is not matching, you have created a service with name my-api but in ingress you have referred it as app1 and app2 which is not available.
Second error is selector label between your deployment and service are not matching. Deployment created with label user-api but in service selector is mentioned as my-api.
If you need 80 port for both the application then you have to create two different services and refer that in your ingress.
Below should work for your requirement.
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: app-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
tls:
- hosts:
- example.com
secretName: app-tls
rules:
- host: example.com
http:
paths:
- path: /my-api1(/|$)(.*)
backend:
serviceName: app1
servicePort: 80
- path: /my-api2
backend:
serviceName: app2
servicePort: 80
---
apiVersion: v1
kind: Service
metadata:
name: app1
spec:
selector:
app: user-api
ports:
- name: app1
port: 3000
targetPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: app2
spec:
selector:
app: user-api
ports:
- name: app2
port: 4000
targetPort: 80
----
apiVersion: apps/v1
kind: Deployment
metadata:
name: user-api
spec:
selector:
matchLabels:
app: user-api
template:
metadata:
labels:
app: user-api
spec:
hostNetwork: true
dnsPolicy: ClusterFirstWithHostNet
containers:
- name: app1
image: XXX
ports:
- name: app1
containerPort: 3000
- name: app2
image: XXX
ports:
- name: app2
containerPort: 4000

Answer 2

You made a mistake on port and targetPort.
It should be:
apiVersion: v1
kind: Service
metadata:
name: my-api
spec:
selector:
app: my-api
ports:
- name: app1
port: 3000
targetPort: 3000
- name: app2
port: 4000
targetPort: 4000
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: app-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
tls:
- hosts:
- example.com
secretName: app-tls
rules:
- host: example.com
http:
paths:
- path: /my-api1(/|$)(.*)
backend:
serviceName: my-api
servicePort: app1
- path: /my-api2
backend:
serviceName: my-api
servicePort: app2
port is for exposing service port
targetPort is targeting a pod exposed port