I have implemented emissary ingress on kubernetes and implemented Deployments, Services and mappings.

Below mapping has been created in emissary

root@master1:~# kubectl get mapping
NAME            SOURCE HOST   SOURCE PREFIX   DEST SERVICE   STATE   REASON
quote-backend                 /backend/       quote
root@master1:~#

At this point when i ran curl command, it was working fine.

root@master1:~# curl -Lv 172.31.11.157/backend/
*   Trying 172.31.11.157:80...
* TCP_NODELAY set
* Connected to 172.31.11.157 (172.31.11.157) port 80 (#0)
> GET /backend/ HTTP/1.1
> Host: 172.31.11.157
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< content-type: application/json
< date: Thu, 20 Jan 2022 14:24:57 GMT
< content-length: 157
< x-envoy-upstream-service-time: 11
< server: envoy
<
{
    "server": "dowdy-snozzberry-0gihwpim",
    "quote": "A principal idea is omnipresent, much like candy.",
    "time": "2022-01-20T14:24:57.136915384Z"
* Connection #0 to host 172.31.11.157 left intact
}root@master1:~#

But as soon as I implemented auth service in emissary ingress, it start giving 403 error code

root@master1:~# kubectl get authservice
NAME             AGE
authentication   140m
root@master1:~#

root@master1:~# curl -Lv 172.31.11.157/backend/
*   Trying 172.31.11.157:80...
* TCP_NODELAY set
* Connected to 172.31.11.157 (172.31.11.157) port 80 (#0)
> GET /backend/ HTTP/1.1
> Host: 172.31.11.157
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 403 Forbidden
< date: Thu, 20 Jan 2022 14:29:33 GMT
< server: envoy
< content-length: 0
<
* Connection #0 to host 172.31.11.157 left intact
root@master1:~#

I have checked all mapping and Services and also checked internet for solution but getting no resolution.

Also I have implemented same configuration as mentioned in below link.

https://www.getambassador.io/docs/emissary/

To double check, my mapping is correct, I tried bypassing authentication by using bypass_auth flag and it start giving 200 code.

Need you support to resolve 403 error code.