nginx serve static html and proxy - nginx

Question

I have a droplet on Digital Ocean, that I am using to host a site and an API for that site.
I would like:
https://example.com to serve the website
https://example.com/api to serve the API, running on port 3000.
Here's my /etc/nginx/nginx.conf file:
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;
error_log /var/log/nginx/http-error.log;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
server {
server_name example.com; # managed by Certbot
listen [::]:443 ssl ipv6only=on; # managed by Certbot
listen 443 ssl; # managed by Certbot
# SSL settings
ssl_certificate /path/to/file.pem; # managed by Certbot
ssl_certificate_key /path/to/file.pem; # managed by Certbot
include /path/to/file.conf; # managed by Certbot
ssl_dhparam /path/to/file.pem; # managed by Certbot
proxy_http_version 1.1;
proxy_set_header Connection 'upgrade';
proxy_set_header Host $http_host;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Real-IP $remote_addr;
proxy_cache_bypass $http_upgrade;
proxy_redirect off;
# Routes
location /api/ {
proxy_pass http://127.0.0.1:3000/;
}
location / {
root /usr/share/nginx/html;
}
error_page 404 /404.html;
location = /40x.html {}
error_page 500 502 503 504 /50x.html;
location = /50x.html {}
}
server {
if ($host = example.com) {
return 301 https://$host$request_uri;
} # managed by Certbot
listen 80 ;
listen [::]:80 ;
server_name example.com;
return 404; # managed by Certbot
}
}
Serving the static html files works great, but the https://example.com/api/ returns a 502: Bad Gateway error. I don't understand what I am doing wrong... any help would be appreciated. Thank you.

Answer 1

Turns out my config was totally fine. I just need to enable networking on the Droplet. I used this post to do so. Thanks, everyone!
In short:
setsebool httpd_can_network_connect on

Answer 2

location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $http_host;
proxy_pass http://127.0.0.1:3000;
}
This normally does not disappoint me. Please try.