Directly hosting BlueMap with external webservers from a FILE storage

BlueMap’s internal webserver is very lightweight and quite fast, but it is quickly overwhelmed by a larger number of concurrent requests.

If you want to optimize the speed of your web-app for a larger audience, you can also host BlueMap directly with external webservers like NGINX or Apache. For this to work you need to do some configuration.

1. The goal
2. NGINX
3. Apache2
   1. Apache2 Modules
   2. Apache2 configuration

The goal

BlueMap renders and saves the map in a lot of small parts called “tiles”. Those tiles are saved in individual files in a tree-like folder-structure here: <webroot>/maps/<map-id>/tiles/. The low-res data is saved in PNG files that can just be served normally. The high-res tile data is saved in GZip-compressed JSON files. The problem now is, that the web-app (browser) is asking for the uncompressed .json files, but a normal webserver only finds the compressed .json.gz ones.

For example: the web-app is asking for a tile: /maps/world/tiles/0/x9/z-8.json. If your webserver is now searching for that file, it will not find it, because the file it needs is actually this one: /maps/world/tiles/0/x9/z-8.json.gz! And on top of that it is compressed.

So we need to do two things:

• Internally redirect the request to the .gz variant of the file
• Tell the browser that the file we send is actually GZip compressed and the browser has to decompress it before giving it to the web-app. (We can do this with the http-header Content-Encoding: gzip)

Optionally:

• If a high-res map tile does not exist, instead of returning a 404 we want to respond with 200 and this file: /assets/emptyTile.json (This removes harmless but annoying 404 errors in the browsers console)
• If a low-res map tile does not exist, instead of returning a 404 and showing errors in the browser console, we return a 204 (No Content).
• If you are using a plugin/mod you usually have live-updating player-markers on your map. For those to work with an external web-server you will also need to reverse-proxy all requests to /maps/*/live/* to the builtin web-server.

NGINX

With NGINX it is actually only one config-line that does both things (finding gz-files and setting the header): gzip_static always;

So with some context your website-config could look like this:

server {
  listen 80;
  server_name yourdomain.com;
  
  # path to bluemap-webroot, bluemap can also be used in a sub-folder .. just adapt the paths accordingly
  root /var/www;
  
  location ~* ^/maps/[^/]*/tiles/ {
    # High-res tiles are stored as precompressed JSON with a fallback to returning an empty tile.
    # Low-res tiles are stored as pngs with a fallback to returning 204 (No Content).
    location ~* \.json$  {
      error_page 404 =200 /assets/emptyTile.json;
      gzip_static always;
    }
    location ~* \.png$ {
      try_files $uri =204;
    }
  }

  # Proxy requests for live data to the bluemaps integrated webserver.
  # If you have multiple servers you will need to proxy each map-id to the correct server.
  location ~* ^/maps/[^/]*/live/ {
    proxy_pass http://127.0.0.1:8100;
  }
}

Important:
The above config is just an example and not a complete config you can just copy&paste. You will need to adapt it to your setup!

Apache2

Apache2 Modules

This needs the HEADERS, REWRITE and all PROXY (PROXY and PROXY_HTTP) modules for Apache to be enabled!
(You can check your enabled modules via # apache2ctl -M and check whether the modules are enabled. Don’t forget to restart apache2 after installing any missing module via # a2enmod MODULENAME)

Apache2 configuration

DocumentRoot /var/www/
<Directory /var/www/>
  allow from all
  Options FollowSymLinks
  Require all granted
  SetEnv no-gzip

  RewriteEngine on

  # Make sure the browser supports gzip encoding before we send it
  # without it, Content-Type will be "application/x-gzip"
  RewriteCond %{HTTP:Accept-Encoding} \b(x-)?gzip\b
  RewriteCond %{REQUEST_FILENAME}.gz -s
  RewriteRule ^(.+) $1.gz
  
  # Check if file doesn't exists and is a map file
  RewriteCond %{REQUEST_URI} "^/maps"
  RewriteCond %{REQUEST_FILENAME} !-s
  RewriteCond %{REQUEST_FILENAME} !-l
  RewriteCond %{REQUEST_FILENAME} !-d
  # Rewrite request to emptyTile
  RewriteRule ^.*$ /assets/emptyTile.json [L]

  # Also add a content-encoding header to tell the browser to decompress
  <FilesMatch .json.gz$>
    ForceType application/json
    Header set Content-Encoding gzip
  </FilesMatch>
  
</Directory>

# Proxy requests to the live data interface to bluemaps integrated webserver  
ProxyPreserveHost On
ProxyPassMatch ^/(maps/[^/]*/live/.*) http://127.0.0.1:8100/$1

Important:
The above config is just an example and not a complete config you can just copy&paste. You will need to adapt it to your setup!