Serving different API versions through content negotiation with Nginx

vhost.conf

map $http_accept $api_version {
    default                                    1;
    "~application/vnd\.namespace\.v1(\+json)?" 1;
    "~application/vnd\.namespace\.v2(\+json)?" 2;
    "~application/vnd\.namespace\.v3(\+json)?" 3;
}

server {
    listen 80;
    server_name api.domain.com;

    root /home/root/api.domain.com/v$api_version/public;
    index index.php;
    charset utf-8;

    # Add header to expose the API version being consumed
    add_header "Api-Version" $api_version;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

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

    access_log off;
    error_log  /var/log/nginx/api.domain.com-error.log error;
    error_page 404 /index.php;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        include fastcgi.conf;
    }

    location ~ /\.ht {
        deny all;
    }
}