node.js - Exposing service from Kubernetes NGINX Ingress controller always return 502 Bad Gateway

Question

I am having issues with request to my NodeJS app running in my kubernetes cluster in digital ocean. Every request returns a 502 Bad Gateway Error. I am not sure what I am missing.

This is what the service config looks like

apiVersion: v1
kind: Service
metadata:
  name:  service-api
  namespace: default
  labels:
    app:  service-api
spec:
  type: ClusterIP
  ports:
    - name: http
      protocol: TCP
      port: 80
      targetPort: 3000
  selector:
    app:  service-api

The Ingress.yml looks like this

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: service-api-ingress
  annotations:
    kubernetes.io/ingress.class: nginx
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/limit-connections: '2'
    nginx.ingress.kubernetes.io/limit-rpm: '60'
    service.beta.kubernetes.io/do-loadbalancer-protocol: "http"
    service.beta.kubernetes.io/do-loadbalancer-algorithm: "round_robin"
    service.beta.kubernetes.io/do-loadbalancer-http2-ports: "443,80"
    service.beta.kubernetes.io/do-loadbalancer-tls-ports: "443"
    service.beta.kubernetes.io/do-loadbalancer-tls-passthrough: "true"
spec:
  tls:
  - hosts:
    - dev-api.service.com
    secretName: service-api-tls
  rules:
  - host: "dev-api.service.com"
    http:
      paths:
      - pathType: Prefix
        path: "/"
        backend:
          service:
            name: service-api
            port:
              number: 80

Whenever I visit the host url I get a 502 error.

This is what appears in the nginx ingress log

2021/01/13 08:41:34 [error] 319#319: *31338 connect() failed (111: Connection refused) while connecting to upstream, client: IP, server: dev-api.service.com, request: "GET /favicon.ico HTTP/2.0", upstream: "http://10.244.0.112:3000/favicon.ico", host: "dev-api.service.com", referrer: "https://dev-api.service.com/status"

Answer 1

As we ( with @Emmanuel Amodu ) have discussed in comment:

mistake was to connect to app using wrong port, port 4000 instead of 3000 as defined in service-api.

For community which will have similar problem please - most important steps for debugging:

1. Checking netstat -plant output table
2. Checking your Nginx Configuration: $ kubectl exec -it -n <namespace-of-ingress-controller> <nginx-ingress-controller-pod> -- cat /etc/nginx/nginx.conf
3. Checking service: $ kubectl describe svc service-api