502 bad gateway using Kubernetes with Ingress controller

Question

I have a Kubernetes setup on Minikube with this configuration:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myappdeployment
spec:
  replicas: 5
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: custom-docker-image:latest
          ports:
            - containerPort: 3000

---
kind: Service
apiVersion: v1
metadata:
  name: example-service
spec:
  selector:
    app: myapp
  ports:
    - protocol: "TCP"
      # Port accessible inside cluster
      port: 3000
      # Port to forward to inside the pod
      targetPort: 3000
  type: NodePort

---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: example-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
  - http:
      paths:
      - path: /
        backend:
          serviceName: example-service
          servicePort: 3000

I took a look at the solution to this Stackoverflow post and it seems my configuration is.. fine?

What am I doing wrong to get 502 Bad Gateway when accessing http://192.xxx.xx.x, my Minikube address? The nginx-ingress-controller logs say:

...
Connection refused while connecting to upstream
...

Another odd piece of info, when I follow this guide to setting up the basic node service on Kubernetes, everything works and I see a "Hello world" page when I open up the Minikube add

Is your app definitely listening on port 3000? If you use kubectl port-forward to the pod, are you able to curl it ok? — wobr
ah interesting, I ran this and it seems I get an error occurred forwarding 3000 -> 3000 - I looked at the logs for that individual pod and it seems I'm missing the MySQL setup, which stops the pod from starting, despite it being green in the Kubernetes dashboard — Sticky
thank you for this! learned a new trick to debug by port-forwarding just one single pod — Sticky
Please, consider posting an answer if the problem is solved. It would be more clear and helpful for the rest of the community. — Wytrzymały Wiktor

Sticky Sticky · Accepted Answer · 2020-01-28T06:04:05

Steps taken: I ran

kubectl port-forward pods/myappdeployment-5dff57cfb4-6c6bd 3000:3000

Then I visited localhost:3000 and saw

This page isn’t working
localhost didn’t send any data.
ERR_EMPTY_RESPONSE

I figured the reason is more obvious in the logs so I ran

kubectl logs pods/myappdeployment-5dff57cfb4-6c6bd

and got

Waiting for MySQL...
no destination
Waiting for MySQL...
no destination
Waiting for MySQL...
no destination
Waiting for MySQL...
no destination
...

Thus I reasoned that I was originally getting a 502 because all of the pods were not running due to no MySQL setup.

502 bad gateway using Kubernetes with Ingress controller

1 Answers