Kubernets - nginx: [emerg] host not found in upstream - docker

Question

I'm attempting to expose a service from my home network via a sub-url from my domain. This service is running on a Kubernetes (K3s) cluster on a Ubuntu 20.04 server. However there's an issue with proxy_pass in that pod that is giving me the `nginx: [emerg] host not found in upstream in 'webhook.lan' error.
Here's an overview of my setup
.lan DNS entry is setup on my router. I have many other services accessible (locally) that use .lan. I'm confident this is setup correctly.
My Ubuntu server is set up to use my router (192.168.0.1) as a DNS server. I can run dig webhook.lan and it's successful. I can also run wget webhook.lan and it downloads the HTML. So, the server can definitely resolve the address. resolvectl status has 192.168.0.1 as the Current DNS Server. Everything seems okay.
The K3s cluster is using an NGINX Ingress controller. I have two hosts setup. A wildcard host for *.lan addresses, along with a host to handle requests from my sub-url sub.url.com. I'm not attempting any sort of communication within the cluster, as I don't see the point (they're both already exposed separately).
Each container has it's own NGINX configuration to handle / proxy requests.
The .lan config looks like this:
server {
server_name service-a.lan;
listen 80;
listen [::]:80;
location / {
include proxy_params;
proxy_pass http://192.168.0.27:8000;
}
}
server {
server_name service-b.lan;
listen 80;
listen [::]:80;
location / {
include proxy_params;
proxy_pass http://192.168.0.27:3000;
}
}
That's just a sample. There's many more. They all work perfect on my local network.
Here's the config for the pod that is handling requests from the web. I currently use it to serve static files, along with a few basic HTML pages. This is where the proxy_pass issue is coming up:
upstream webhook {
server webhook.lan;
}
server {
server_name genweb;
listen 80;
listen [::]:80;
#basic welcome screen
location / {
alias /srv/web/;
try_files $uri $uri/ /index.html;
}
#static images, music, etc.
location /static {
alias /app/static;
autoindex on;
}
#problem area!!
location /webhook {
#resolver 127.0.0.11;
resolver 192.168.0.1;
include proxy_params;
proxy_pass http://webhook;
}
}
Originally, I just imported proxy_params and used the proxy_pass directive. Since that's all I was doing with the other container. Then, I tried using upstream{}; tried resolver 192.168.0.1 to make it resolve to the router. Finally, tried resolver 127.0.0.11 because that's the docker localhost (apparently).
No dice. Also, I should mention that the pod/deployment doesn't even start. It got that error from kubectl logs. It tries to restart a bunch of times, and eventually gives a status of Failure (I think), and never starts. Commenting out the webhook location in the NGINX config allows it to start right up.
I'm guessing the issue comes down to NGINX in the sub-url's container not being able to resolve 192.168.0.1, but I cannot figure out why.
Here's the Dockerfile (which I basically copied from the other running app) and Service/Deployment yaml file, in case that's where the problem lies:
Dockerfile
FROM nginx:1.21.4
RUN rm /etc/nginx/conf.d/default.conf
COPY web-nginx.conf /etc/nginx/conf.d
COPY proxy_params /etc/nginx
RUN mkdir -p /srv/web/static
COPY index.html /srv/web
ADD static /srv/web/static
web-service.yml
apiVersion: v1
kind: Service
metadata:
name: gen-web-service
spec:
selector:
app: genweb
ports:
- protocol: TCP
port: 8080
targetPort: 80
type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: gen-web-deployment
labels:
app: genweb
spec:
replicas: 1
selector:
matchLabels:
app: genweb
template:
metadata:
labels:
app: genweb
spec:
containers:
- name: genweb
image: genweb:v1.0.16
imagePullPolicy: Never
ports:
- containerPort: 80
volumeMounts:
- name: gen-web-volume
mountPath: /app/static
volumes:
- name: gen-web-volume
hostPath:
path: /srv/web/static