How to use Ingress Nginx to route requests by url query string? - nginx

Question

We would like to use annotation for redirecting requests to a different backend service based on url args (query)
Example:
https://example.com/foo?differentQueryString=0 -> service-a
https://example.com/foo/bar?queryString=0 - service-b
Notes: path does not matter, this can be either /foo/bar or /foo or /bar/foo
We followed up on this
Kubernetes NGINX Ingress controller - different route if query string exists
and this
Kubernetes ingress routes with url parameter
But we don't want to setup ConfigMap just for this and also we don't want to duplicate requests to the ingress but rewriting
This is what we tried
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: test-ingress
annotations:
nginx.ingress.kubernetes.io/configuration-snippet: |
if ($args ~ queryString=0){
backend.service.name = service-b
}
spec:
ingressClassName: nginx
rules:
- host: example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: service-a
port:
number: 80
- path: /
pathType: Prefix
backend:
service:
name: service-b
port:
number: 80
We were expecting to get the response but we got 502 from the Ingress Nginx

Answer 1

We managed to find a nice solution without rewriting and ConfigMap
Works great and also include Nginx Ingress metrics so we can do HPA accordingly
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: test-ingress
annotations:
nginx.ingress.kubernetes.io/configuration-snippet: |
if ($args ~ queryString=0){
set $proxy_upstream_name "default-service-b-80";
set $proxy_host $proxy_upstream_name;
set $service_name "service-b";
}
spec:
ingressClassName: nginx
rules:
- host: example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: service-a
port:
number: 80
- path: /
pathType: Prefix
backend:
service:
name: service-b
port:
number: 80
$proxy_upsteam_name convention is NAMESPACE-SERVICE_NAME-PORT