Issue azure containergroup 2fauth with sidecar caddy setup

[nsaasman]

I've setup a containergroup in azure to reverse proxy with sidecar caddy. The containers are running properly. The domain is certed. The issue is that I get a white screen when visiting the site. In the logging of the 2fauth container i see a GET request comming in. Has anyone an idea what's wrong?

2fauth log:
127.0.0.1 - - [05/Jan/2024:09:00:45 +0000] "GET /favicon_lg.png HTTP/1.1" 200 2410 "https://[DOMAIN].westeurope.azurecontainer.io/favicon_lg.png" "Mozilla/5.0 (X11; Linux armv7l) AppleWebKit/537.36 (KHTML, like Gecko) Raspbian Chromium/74.0.3729.157 Chrome/74.0.3729.157 Safari/537.36"

Yaml file:

name: 2fauth
apiVersion: "2021-10-01"
location: westeurope
properties:
containers:
- name: reverse-proxy
properties:
image: caddy:2.7.6
ports:
- protocol: TCP
port: 80
- protocol: TCP
port: 443
resources:
requests:
memoryInGB: 1.0
cpu: 1.0
limits:
memoryInGB: 1.0
cpu: 1.0
volumeMounts:
- name: proxy-caddyfile
mountPath: /etc/caddy
- name: proxy-data
mountPath: /data
- name: proxy-config
mountPath: /config
- name: 2fauth
properties:
image: 2fauth/2fauth
ports:
- port: 8000
protocol: TCP
resources:
requests:
memoryInGB: 1.0
cpu: 1.0
limits:
memoryInGB: 1.5
cpu: 1.0
ipAddress:
ports:
- protocol: TCP
port: 80
- protocol: TCP
port: 443
type: Public
dnsNameLabel: [DOMAIN]
osType: Linux
volumes:
- name: proxy-caddyfile
azureFile:
shareName: proxy-caddyfile
storageAccountName: "storage"
storageAccountKey: "SECRET"
- name: proxy-data
azureFile:
shareName: proxy-data
storageAccountName: "storage"
storageAccountKey: "SECRET"
- name: proxy-config
azureFile:
shareName: proxy-config
storageAccountName: "storage"
storageAccountKey: "SECRET"

Caddyfile:
[DOMAIN].westeurope.azurecontainer.io {
reverse_proxy localhost:8000
}

[Bubka]

How did you set the APP_URL env var? It should be set with the public address of the instance, so https://[DOMAIN].westeurope.azurecontainer.io in your case.