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Directly hosting BlueMap with external webservers from a FILE storage

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

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
    3. Caddy 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 PRBM (modified PRWM) files. The problem now is that the web-app (browser) is asking for the uncompressed .prbm files, but a normal webserver only finds the compressed .prbm.gz ones.

For example: the web-app is asking for a tile: /maps/world/tiles/0/x9/z-8.prbm. 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.prbm.gz! And on top of that it is compressed.

Next to the map-tiles there might be more map-files that are only available in their compressed form. For example the <webroot>/maps/<map-id>/textures.json.gz.

So we need to do two things:

  • Internally redirect the request to the .gz variant of the file if one is available
  • 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 any 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/ {
    # find gz-files and set the "Content-Encoding: gzip" header
    gzip_static always;

    # convert 404 into 204 for map-tiles
    location ~* ^/maps/[^/]*/tiles/ {
      error_page 404 = @empty;
    }
  }
  
  location @empty {
    return 204;
  }

  # OPTIONAL:
  # 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

  # if a .gz file exists rewrite to that 
  RewriteCond %{REQUEST_FILENAME}.gz -s
  RewriteRule ^(.+) $1.gz

  # add a content-encoding header to tell the browser to decompress
  <FilesMatch .gz$>
    Header set Content-Encoding gzip
  </FilesMatch>
  
  # if a map-tile doesnt exist, send a 204
  RewriteCond %{REQUEST_URI} "^/maps/[^/]*/tiles/"
  RewriteCond %{REQUEST_FILENAME} !-s
  RewriteCond %{REQUEST_FILENAME} !-l
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^.*$ - [R=204,L]
</Directory>

# OPTIONAL:
# 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!

Caddy configuration

yourdomain.com {
	# path to bluemap-webroot, BlueMap can also be used in a sub-folder .. just adapt the paths accordingly
	root /var/www
	file_server

	# Match the textures.json file & .prbm files
	@gz path /maps/*/textures.json *.prbm
	# Find .gz files (if not found respond with 204) for the above matcher, and set the "Content-Encoding gzip" header
	handle @gz {
		try_files {path}.gz =204
		header Content-Encoding gzip
	}

	# Respond with 204 for non-existant map-tiles
	@204 path */tiles/*
	handle @204 {
		try_files {path} =204
	}
}

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!