Problem with NGINX, Kubernetes and CloudFlare - nginx

Question

I am experiencing exactly this issue: Nginx-ingress-controller fails to start after AKS upgrade to v1.22, with the exception that none of the proposed solutions is working for my case.
I am running a Kubernetes Cluster on Oracle Cloud and I accidentally upgraded the cluster and now I cannot connect anymore to the services through nginx-controller. After reading the official nginx documentation, I am aware of the new version of nginx, so I checked the documentation and re-installed the nginx-controller following Oracle Cloud official documentation.
I am able to perform step by step as I run:
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.44.0/deploy/static/provider/cloud/deploy.yaml
And then an ingress-nginx namespace is created and a LoadBalancer is created. Then as in the guide I have created a simple hello application (though not running on port 80):
apiVersion: apps/v1
kind: Deployment
metadata:
name: docker-hello-world
labels:
app: docker-hello-world
spec:
selector:
matchLabels:
app: docker-hello-world
replicas: 1
template:
metadata:
labels:
app: docker-hello-world
spec:
containers:
- name: docker-hello-world
image: scottsbaldwin/docker-hello-world:latest
ports:
- containerPort: 8088
---
apiVersion: v1
kind: Service
metadata:
name: docker-hello-world-svc
spec:
selector:
app: docker-hello-world
ports:
- port: 8088
targetPort: 8088
type: ClusterIP
and then the ingress
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: hello-world-ing
annotations:
kubernetes.io/ingress.class: "nginx"
spec:
tls:
- secretName: tls-secret
rules:
- http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: docker-hello-world-svc
port:
number: 8088
But when running the curl commands I only get a curl: (56) Recv failure: Connection reset by peer.
So I then tried to connect to some python microservices that are already running by simply editing the ingress, but whatever I do I get the same error message. And when setting the host as the following:
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: hello-world-ing
namespace: ingress-nginx
annotations:
kubernetes.io/ingress.class: "nginx"
spec:
rules:
- host: SUBDOMAIN.DOMAIN.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: ANY_MICROSERVICE_RUNNING_IN_CLUSTER
port:
number: EXPOSED_PORT_BY_MICROSERVICE
Then, by setting the subdomain on CloudFlare I only get a 520 Bad Gateway.
Can you help me find what is that I do not see?

Answer 1

This may be related to your Ingress resource.
In Kubernetes versions v1.19 and above, Ingress resources should use ingressClassName instead of the older annotation syntax. Additional information on what should be done when upgrading can be found on the official Kubernetes documentation.
However, with the changes it requires at face value, from the information you're provided so far, your Ingress resource should look this:
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: hello-world-ing
spec:
ingressClassName: nginx
rules:
- host: SUBDOMAIN.DOMAIN.com
http:
paths:
- backend:
service:
name: docker-hello-world-svc
port:
number: 8088
path: /
pathType: Prefix
tls:
- hosts:
- SUBDOMAIN.DOMAIN.com
secretName: tls-secret
Additionally, please provide the deployment Nginx-ingress logs if you still have issues, as the Cloudflare error does not detail what could be wrong apart from providing a starting point.
As someone who uses Cloudflare and Nginx, there are multiple reasons why you're receiving a 520 error, so it'd be better if we could reduce the scope of what could be the main issue. Let me know if you have any questions.