TLS Reverse Proxy Configuration

When running LocalAI behind a TLS termination reverse proxy, the Web UI may fail to load static assets (CSS, JS) correctly because the application doesn't automatically detect that it's being served over HTTPS. This guide explains how to properly configure your reverse proxy to work with LocalAI.

How It Works

LocalAI uses the X-Forwarded-Proto HTTP header to determine the protocol used by clients. When this header is set to https, LocalAI will generate HTTPS URLs for static assets in the Web UI.

Running behind a reverse proxy (HTTPS / subpath)

LocalAI does not terminate TLS itself, so HTTPS is provided by a reverse proxy in front of it. Self-referential links (generated image and video URLs, async job status URLs, OAuth callbacks) need the externally visible scheme, host and port.

LocalAI determines these in this order:

1. LOCALAI_BASE_URL - if set, it is authoritative for the origin. Set it to the externally visible base URL, e.g. LOCALAI_BASE_URL=https://localai.example.com or https://192.168.0.13:34567. Recommended whenever links come back with the wrong scheme or host.
2. Otherwise, the X-Forwarded-Proto and X-Forwarded-Host headers (or the RFC 7239 Forwarded header) sent by the proxy. Ensure your proxy forwards X-Forwarded-Proto: https.

A reverse-proxy subpath mount is supported via X-Forwarded-Prefix; it is appended to LOCALAI_BASE_URL when both are present.

Required Headers

Your reverse proxy must forward these headers to LocalAI:

HAProxy Configuration

frontend https-in
    bind *:443 ssl crt /path/to/cert.pem
    mode http
    
    # Set the X-Forwarded-Proto header
    http-request set-header X-Forwarded-Proto https
    
    # Pass the original host
    http-request set-header X-Forwarded-Host %[hdr(host)]
    
    # If serving under a sub-path, set the prefix
    # http-request set-header X-Forwarded-Prefix /localai
    
    default_backend localai

backend localai
    mode http
    server localai1 127.0.0.1:8080 check

Apache Configuration

<VirtualHost *:443>
    ServerName your-domain.com
    SSLEngine on
    SSLCertificateFile /path/to/cert.pem
    SSLCertificateKeyFile /path/to/key.pem
    
    # Enable proxy and headers modules
    ProxyRequests Off
    ProxyPreserveHost On
    
    <Proxy *>
        Require all granted
    </Proxy>
    
    # Set the X-Forwarded-Proto header
    RequestHeader set X-Forwarded-Proto "https"
    
    # Set the X-Forwarded-Host header (optional, usually automatic)
    RequestHeader set X-Forwarded-Host "%{HTTP_HOST}s"
    
    # If serving under a sub-path
    # RequestHeader set X-Forwarded-Prefix "/localai"
    
    ProxyPass / http://127.0.0.1:8080/
    ProxyPassReverse / http://127.0.0.1:8080/
</VirtualHost>

Nginx Configuration

server {
    listen 443 ssl;
    server_name your-domain.com;
    
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    
    # Set the X-Forwarded-Proto header
    proxy_set_header X-Forwarded-Proto $scheme;
    
    # Pass the original host
    proxy_set_header X-Forwarded-Host $host;
    
    # If serving under a sub-path
    # proxy_set_header X-Forwarded-Prefix /localai;
    
    # Other proxy settings
    proxy_pass http://127.0.0.1:8080;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
}

Serving Under a Sub-Path

If you serve LocalAI under a sub-path (e.g., https://your-domain.com/localai), you need to:

1. Configure your reverse proxy to set the X-Forwarded-Prefix header

Example with Nginx:

proxy_set_header X-Forwarded-Prefix /localai;

Testing Your Configuration

1. Start LocalAI: localai
2. Configure your reverse proxy as shown above
3. Access the Web UI through the proxy
4. Check the browser's developer console for any mixed content warnings or failed asset loads
5. Verify that the HTML source contains https:// URLs for static assets

Troubleshooting

Static Assets Not Loading

• Verify the X-Forwarded-Proto header is being forwarded
• Check that the header value is exactly https (lowercase)
• Inspect the network tab in your browser to see which requests are failing

Mixed Content Warnings

• Ensure LocalAI is generating HTTPS URLs (check the BaseURL middleware is working)
• Verify the X-Forwarded-Proto header is set before LocalAI processes the request

Redirect Loops

• Check that your proxy is not adding duplicate headers
• Verify X-Forwarded-Proto is not being set to both http and https

Security Note

When using reverse proxies, ensure your proxy only accepts connections from trusted sources and properly validates SSL certificates. Never expose LocalAI directly to the internet without TLS termination.