Caddyfile & multiple sites

Nexus uses Caddy as its reverse proxy. Caddy handles HTTPS automatically via Let’s Encrypt and proxies requests to the Nexus container running on port 4000.

The canonical Caddyfile

The canonical Caddyfile lives at /opt/nexus/Caddyfile. This is the file to edit — not /etc/caddy/Caddyfile.

On every nexus-update run, the update script copies /opt/nexus/Caddyfile to /etc/caddy/Caddyfile and reloads Caddy:

cp /opt/nexus/Caddyfile /etc/caddy/Caddyfile
systemctl reload caddy

Any changes made directly to /etc/caddy/Caddyfile will be overwritten the next time nexus-update runs. Always edit /opt/nexus/Caddyfile so changes survive updates.

nexus-update preserves /opt/nexus/Caddyfile — it is excluded from the rsync that applies the new release. Your custom site blocks, additional domains, and any other Caddyfile additions will survive updates untouched.

Default Caddyfile structure

The installer writes a Caddyfile for your forum domain with:

Security headers (Strict-Transport-Security, X-Content-Type-Options, X-Frame-Options, Referrer-Policy)
Long-lived caching for static assets (/assets/*, /images/*, /favicon.ico)
Immutable caching for avatars and logos (UUID filenames, safe to cache forever)
Immutable caching for self-hosted Font Awesome fonts
Gzip compression for all responses except SSE endpoints (Server-Sent Events must not be buffered)
WebSocket proxying to localhost:4000
General reverse proxy to localhost:4000

For apex domains, an optional www. redirect block is also written.

Adding other sites

To host a homepage, docs site, or any other content on the same server, add additional site blocks to /opt/nexus/Caddyfile:

your-forum.com {
    # ... existing Nexus configuration ...
}

nexusprism.org {
    root * /var/www/homepage
    file_server
}

docs.nexusprism.org {
    root * /var/www/docs
    file_server
}

After editing, apply the changes:

cp /opt/nexus/Caddyfile /etc/caddy/Caddyfile
systemctl reload caddy

Caddy will automatically obtain and renew TLS certificates for any new domains you add, as long as their DNS A records point to the server and ports 80 and 443 are open.

Applying Caddyfile changes

Any time you edit /opt/nexus/Caddyfile, apply it with:

cp /opt/nexus/Caddyfile /etc/caddy/Caddyfile
systemctl reload caddy

systemctl reload caddy applies the configuration gracefully without dropping active connections. Use systemctl restart caddy only if a reload doesn’t take effect.