When exposing a service via ingress inginx on kubernetes, the only http response code upon requesting something is 200.

The web app is basically a form that uploads images, stores them somewhere, and responds with the according to code (e.g. bad request, or created with the URI location in the header). It expects a Request with multipart/form-data on an API address as following: "http://{anyAddress}/api/images?directory={whereToStore}?processing={someProcessingTags}"

The web app works as expected locally and as a single container on docker.

So when the service is accessed via ingress, it first responds with the form as expected. You can specify settings and an image to upload. Upon sending the Request the file is correctly uploaded to the web app and processed, the web app then sends the expected 201 created, but the response that gets back to the browser is always 200 OK. I have no idea why.

This is on a docker for desktop + kubernetes server that runs locally.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/rewrite-target: /
    nginx.ingress.kubernetes.io/proxy-body-size: 25m
spec:
  rules:
    - http:
        paths:
          - path: /image-upload
            backend:
              serviceName: image-upload-service
              servicePort: http

---

apiVersion: v1
kind: Service
metadata:
  name: image-upload-service
spec:
  type: LoadBalancer
  selector:
    run: image-upload
  ports:
    - name: http
      port: 80
      targetPort: api
      protocol: TCP
    - name: https
      port: 443
      targetPort: api
      protocol: TCP

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: image-upload-cluster
  labels:
    run: image-upload
spec:
  selector:
    matchLabels:
      run: image-upload
  replicas: 2
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 25%
      maxSurge: 0
  template:
    metadata:
      labels:
        run: image-upload
    spec:
      volumes:
        - name: shared-volume
          hostPath:
            path: /exports
      containers:
        - name: image-upload
          image: calyxa/image-service
          imagePullPolicy: IfNotPresent
          volumeMounts:
            - mountPath: /exports
              name: shared-volume
          resources:
            requests:
              cpu: 10m
          ports:
            - containerPort: 3000
              name: api
          readinessProbe:
            httpGet:
              path: /
              port: 3000
            initialDelaySeconds: 5
            periodSeconds: 5
            successThreshold: 1

I expect upon sending a Request with an image file to get a Response with an according to status code, that is 400 bad request or 201 created (with a location in the header).

The Response is always 200 OK, even when the web app crashes because of the Request.

If the web app itself is not running (because it crashed, for instance), I get a 503 service unavailable, as expected.