nginx-redirector

redirect

# NGINX REDIRECTOR
#
# This nginx config will redirect a URL from redirect.example.com to any domain passed in using the redirectURL parameter
#
# Example:
#   https://redirect.example.com/api/assets?redirectURL=mydomain.com
#     would be redirected to 
#   https://mydomain.com/api/assets
#
# The redirect is done by returning an HTTP 307 (Temporary Redirect) response. With this response code the client will
# do the exat some request again at the new URL (passed in the `Location` header). The response will be sent once the
# headers have been read, meaning the body will probably not be fully sent to the "redirector".

server {
    server_name redirect.example.com;

    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    location / {
        # Respond to request immediately after having read the headers
        client_body_buffer_size 16k;
        client_max_body_size 10g;
        proxy_request_buffering off;
        client_body_in_single_buffer off;

        # Return 400 if redirectURL is missing
        if ($arg_redirectURL = "") {
            return 400 "Missing redirectURL parameter";
        }

        # Remove redirectURL from query string
        set $qs "";
        if ($args ~* "(?:^|&)redirectURL=[^&]*(?:&(.*))?$") {
            set $qs $1;
        }

        # Ensure redirect URL starts with https://
        set $target https://$arg_redirectURL;

        # Build full redirect URL with path
        set $full_redirect $target$uri;
        if ($qs != "") {
            set $full_redirect $target$uri?$qs;
        }

        # Issue a 307 redirect
        return 307 $full_redirect;
    }

    ssl_certificate /etc/letsencrypt/live/redirect.example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/redirect.example.com/privkey.pem; # managed by Certbot
}