How can I modify the nginx configuration in Railway?

I'm getting a "413 Request Entity Too Large" when uploading images to my Laravel app deployed with Railway (which is using Nixpacks).

I've seen other questions that this can be solved by modifying the "client_max_body_size 20M;" in in /etc/nginx/nginx.conf.

However, I can't figure out how can I access this configuration file Railway.

How can I make such a configuration in Railway?

To modify nginx configuration using Nixpacks you can create a nginx.conf or nginx.template.conf file in the root folder of your app and add there your configurations. The content of the file for this case would be:

worker_processes 5;
daemon off;

worker_rlimit_nofile 8192;

events {
  worker_connections  4096;  # Default: 1024
}

http {
    include    $!{nginx}/conf/mime.types;
    index    index.html index.htm index.php;

    default_type application/octet-stream;
    log_format   main '$remote_addr - $remote_user [$time_local]  $status '
        '"$request" $body_bytes_sent "$http_referer" '
        '"$http_user_agent" "$http_x_forwarded_for"';
    access_log /dev/stdout;
    error_log /dev/stdout;
    sendfile     on;
    tcp_nopush   on;
    server_names_hash_bucket_size 128; # this seems to be required for some vhosts


    client_max_body_size 20M;  # Modify this to fit you needs

    server {
        listen ${PORT};
        listen [::]:${PORT};
        server_name localhost;

        $if(NIXPACKS_PHP_ROOT_DIR) (
            root ${NIXPACKS_PHP_ROOT_DIR};
        ) else (
            root /app;
        )

        add_header X-Frame-Options "SAMEORIGIN";
        add_header X-Content-Type-Options "nosniff";

        index index.php;

        charset utf-8;

        $if(IS_LARAVEL) (
            location / {
                try_files $uri $uri/ /index.php?$query_string;
            }
        ) else ()

        location = /favicon.ico { access_log off; log_not_found off; }
        location = /robots.txt  { access_log off; log_not_found off; }

        $if(IS_LARAVEL) (
            error_page 404 /index.php;
        ) else ()

        location ~ \.php$ {
            fastcgi_pass 127.0.0.1:9000;
            fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
            include $!{nginx}/conf/fastcgi_params;
            include $!{nginx}/conf/fastcgi.conf;
        }

        location ~ /\.(?!well-known).* {
            deny all;
        }
    }
}

I'm still experiencing problems with the image upload, but this solve the original question.

Fonts:

https://nixpacks.com/docs/providers/php https://github.com/railwayapp/nixpacks/blob/main/src/providers/php/nginx.template.conf