containerized reverse proxy showing default site - docker

Question

No matter what I do, I keep running into the problem where my website publishes the default nginx website. I'm trying to dockerize my webserver such that it can point to home assistant running in another container. I've been able to get it to work when both were hosted on the same raspi, not running in containers, but not when both are running in containers.
I've attached my nginx.conf, Dockerfile and default.conf that I was using to start the environment up. I've spent the last 2 days looking for someone who was trying to do something similar, but I assume I'm making such a stupid mistake that most have been able to figure it out on their own..
nginx.conf:
user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
#tcp_nopush on;
keepalive_timeout 65;
#gzip on;
include /etc/nginx/conf.d/*.conf;
}
default.conf (/etc/nginx/conf.d/hass.conf)
map $http_upgrade $connection_upgrade {
default upgrade;
'' close;
}
server {
# Update this line to be your domain
server_name nekohouse.ca;
# These shouldn't need to be changed
listen [::]:80 default_server ipv6only=off;
return 301 https://$host$request_uri;
}
server {
# Update this line to be your domain
server_name nekohouse.ca;
# Ensure these lines point to your SSL certificate and key
ssl_certificate fullchain.pem;
ssl_certificate_key privkey.pem;
# Use these lines instead if you created a self-signed certificate
# ssl_certificate /etc/nginx/ssl/cert.pem;
# ssl_certificate_key /etc/nginx/ssl/key.pem;
# Ensure this line points to your dhparams file
ssl_dhparam /etc/nginx/dhparams.pem;
# These shouldn't need to be changed
listen [::]:443 default_server ipv6only=off; # if your nginx version is >= 1.9.5 you can also add the "http2" flag here
add_header Strict-Transport-Security "max-age=31536000; includeSubdomains";
ssl on;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
ssl_prefer_server_ciphers on;
ssl_session_cache shared:SSL:10m;
proxy_buffering off;
location / {
proxy_pass http://localhost:8123;
proxy_set_header Host $host;
proxy_redirect http:// https://;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;
}
}
default.conf (/etc/nginx/conf.d/default.conf)
server {
listen 8100;
server_name localhost;
#charset koi8-r;
#access_log /var/log/nginx/host.access.log main;
location / {
root /usr/share/nginx/html;
index index.html index.htm;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# proxy_pass http://127.0.0.1;
#}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
#location ~ \.php$ {
# root html;
# fastcgi_pass 127.0.0.1:9000;
# fastcgi_index index.php;
# fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
# include fastcgi_params;
#}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
#location ~ /\.ht {
# deny all;
#}
}

Answer 1

The problem is because of this line
proxy_pass http://localhost:8123;
When running in containers, you should understand that localhost refers to the nginx container and not the docker host.
So, you should either change localhost to the hostname of your docker host or use docker-compose so that you can change it to the name of the container defined.
If you are just running the containers separately, you could also just use the container IP for now but note that it will change everytime the container is restarted.