k8s ngnix container return json response - nginx

Question

I have a k8s cluster, among other things running an nginx.
when I do curl -v <url> I get
HTTP/1.1 200 OK
< Content-Type: text/html
< Date: Fri, 24 Mar 2017 15:25:27 GMT
< Server: nginx
< Strict-Transport-Security: max-age=15724800; includeSubDomains; preload
< Content-Length: 0
< Connection: keep-alive
<
* Curl_http_done: called premature == 0
* Connection #0 to host <url> left intact
however when I do curl -v <url> -H 'Accept: application/json' I get
< HTTP/1.1 200 OK
< Content-Type: text/html
< Date: Fri, 24 Mar 2017 15:26:10 GMT
< Server: nginx
< Strict-Transport-Security: max-age=15724800; includeSubDomains; preload
< Content-Length: 0
< Connection: keep-alive
<
* Curl_http_done: called premature == 0
* Connection #0 to host <url> left intact
* Could not resolve host: application
* Closing connection 1
curl: (6) Could not resolve host: application
My task is to get the request to return a json not html.
To my understanding I have to create an ingress-controller and modify the ngnix.conf somehow, I've been trying for a few days now but can't get it right. Any kind of help would be most appreciated.
The following are of the yaml files I've been using:
configmap:
apiVersion: v1
data:
server-tokens: "false"
proxy-body-size: "4110m"
server-name-hash-bucket-size: "128"
kind: ConfigMap
metadata:
name: nginx-load-balancer-conf
labels:
app: nginx-ingress-lb
daemonset:
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: nginx-ingress-lb
labels:
app: nginx-ingress-lb
spec:
template:
metadata:
labels:
name: nginx-ingress-lb
app: nginx-ingress-lb
spec:
terminationGracePeriodSeconds: 60
nodeSelector:
NodeType: worker
containers:
- image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.1
name: nginx-ingress-lb
imagePullPolicy: Always
readinessProbe:
httpGet:
path: /healthz
port: 10254
scheme: HTTP
livenessProbe:
httpGet:
path: /healthz
port: 10254
scheme: HTTP
initialDelaySeconds: 10
timeoutSeconds: 1
# use downward API
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
ports:
- containerPort: 80
hostPort: 80
- containerPort: 443
hostPort: 443
args:
- /nginx-ingress-controller
- --default-backend-service=$(POD_NAMESPACE)/default-http-backend
- --configmap=$(POD_NAMESPACE)/nginx-load-balancer-conf
deployment:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: default-http-backend
labels:
app: default-http-backend
spec:
replicas: 2
template:
metadata:
labels:
app: default-http-backend
spec:
terminationGracePeriodSeconds: 60
containers:
- name: default-http-backend
# Any image is permissable as long as:
# 1. It serves a 404 page at /
# 2. It serves 200 on a /healthz endpoint
image: gcr.io/google_containers/defaultbackend:1.2
livenessProbe:
httpGet:
path: /healthz
port: 8080
scheme: HTTP
initialDelaySeconds: 30
timeoutSeconds: 5
ports:
- containerPort: 8080
resources:
limits:
cpu: 100m
memory: 20Mi
requests:
cpu: 100m
memory: 20Mi
service:
apiVersion: v1
kind: Service
metadata:
name: default-http-backend
labels:
app: default-http-backend
spec:
selector:
app: default-http-backend
ports:
- port: 80
targetPort: 8080

Answer 1

Remove the space after colon in curl -v <url> -H 'Accept: application/json'
The error message Could not resolve host: application means that it's taking application/json as the URL, instead of a header.

Answer 2

There are two things:
Exposing your app
Making your app return json
The ingess is only relevant to expose your app. And that is not the only option, you can use service (type Load balancer, for example) to achieve that too on most cloud providers. So, I'd keep it simple and not use ingress for now, until you solve the second problem.
As it has been explained, your curl has a syntax problem and that's why it shows curl: (6) Could not resolve host: application.
The other thing is fixing that won't make your app return json. And this is because you are only saying you accept json with that header. But if you want your app to return json, then you need to write it on your app. nginx can't guess how you want to map your HTML to json. There is much no other way than writting it, at least that I know of :-/