I have written an application that runs a FastAPI server inside a Kubernetes pod. The external communication with the pod goes through an nginx ingress controller in a separate pod. I am running nginx:1.17.0.

When it is all up and running I can use curl calls to interact with the app server through the ingress address, and access all the simple GET paths as well as address/openapi.json in my browser. I can also access the interactive documentation page if I use the internal ip of the app service in Kubernetes. However trying to reach the interactive documentation page (address/docs#/default/) gives me an error regarding /openapi.json.

Since the curl calls work as expected I do not think the problem is necessarily in the ingress definition but as using the internal ip of the app also works fine the issue should not be inside the app.
I have included the ingress definition file below.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app-nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.17.0
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 80

---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: my-app-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  rules:
  - host: my-host.info
    http:
      paths:
      - path: /server(/|$)(.*)
        backend:
          serviceName: my-app-service # This is the service that runs my fastAPI server pod
          servicePort: 80

EDIT
This is the service.yaml file

apiVersion: v1
kind: Service
metadata:
  name: my-app-service
spec:
  type: ClusterIP
  selector:
    app: server
  ports:
    - protocol: "TCP"
      port: 80
      targetPort: 80

As the service is a ClusterIP inside my local cluster I have might be able to curl straight to it, I have not tried though. When I curl I use commands like

curl -X GET "http://my-host.info/server/subpath/" -H "accept: application/json"
curl -X POST "http://my-host.info/server/subpath/update/" -H "accept: application/json"

from outside the local cluster.

These are all the services that are running:

NAMESPACE              NAME                        TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                  AGE
default                kubernetes                  ClusterIP   10.96.0.1       <none>        443/TCP                  11d
default                my-app-service              ClusterIP   10.96.68.29     <none>        80/TCP                   18h
kube-system            kube-dns                    ClusterIP   10.96.0.10      <none>        53/UDP,53/TCP,9153/TCP   28d
kubernetes-dashboard   dashboard-metrics-scraper   ClusterIP   10.96.114.1     <none>        8000/TCP                 28d
kubernetes-dashboard   kubernetes-dashboard        ClusterIP   10.96.249.255   <none>        80/TCP                   28d

and inside my /etc/hosts file I have connected 10.0.0.1 (cluster "external" IP) to my-host.info.

Any ideas of why this is happening?