Deployment

There are different ways to deploy Python web applications. MapProxy implements the Web Server Gateway Interface (WSGI) which is for Python what the Servlet API is for Java.

The WSGI standard allows to choose between a wide range of servers and server integration components.

MapProxy uses Paste Deploy to start these servers with a configured MapProxy application. It is a dependency of MapProxy and should be installed already. You can access the tool with paster serve.

Paste Deploy needs a configuration where the application (MapProxy in this case) and the server are defined. The etc/ directory created with paster create (see Installation) already contains two example configurations. Both configurations define MapProxy as the WSGI application to start and setup some configuration options.

Testing

The develop.ini uses the Paster HTTP Server as the WSGI server. This server already implements HTTP so you can directly access the MapProxy with your Web or GIS client on port 8080.

With the --reload option of paster serve MapProxy will take notice when you change any configuration and will reload these files.

This server is sufficient for local testing of the configuration. For production deployment we recommend other solutions.

Production

FastCGI is a protocol to integrate web applications into web servers. FastCGI is language-independent and implemented by most popular web servers like Apache, Lighttpd or Nginx. The applications run isolated from the web server. In this case you do not start MapProxy as an HTTP server but as a FastCGI server.

The example paster configuration config.ini does this. By default the configured server listens on a socket file (var/fcgi-socket) to which you should point your web server. But you can also use TCP/IP with the host and port option.

Note

You need to install flup to run MapProxy as a FastCGI server: pip install flup

To start MapProxy as a FastCGI server:

paster serve etc/config.ini

Next you must configure you web server to talk to this FastCGI server.

Lighttpd

Here is an example Lighttpd configuration:

$HTTP["host"] == "example.org" {
  fastcgi.server += (
    "/proxy" => ((
      "check-local" => "disable",
      "socket"      => "/path/to/mymapproxy/var/fcgi-socket"
    ))
  )
}

The first line restricts this configuration to the example.org hostname. In the third line you set the URL path where MapProxy should listen. The socket option should point to the fcgi-socket file that is used to communicate with the MapProxy FastCGI server.

With this configuration you can access the MapProxy WMS at http://example.org/proxy/service?

Apache mod_fastcgi

You can use the following snippet to add the MapProxy FastCGI to an Apache installation:

LoadModule fastcgi_module modules/mod_fastcgi.so

<IfModule mod_fastcgi.c>
 FastCGIExternalServer /tmp/madeup -socket /path/to/mymapproxy/var/fcgi-socket
 Alias /proxy /tmp/madeup
</IfModule>

Note

/tmp/madeup is just a dummy value and you can choose any path you want, the only limitation is that the directory must exist but not the file. In this example there must be a /tmp directory but the file madeup should not exist.

nginx

The following snippet adds MapProxy to an nginx installation. Note that you need to split the URI manually if you use an nginx version before 0.7.31. If you have a more recent version, you can use fastcgi_split_path_info.

server {
  # server options
  # ...

  location /proxy {
    if ($uri ~ "^(/proxy)(/.*)$") {
      set $script_name  $1;
      set $path_info  $2;
    }
    fastcgi_pass   unix:/path/to/mymapproxy/var/fcgi-socket;
    include fastcgi_params;
    fastcgi_param  SCRIPT_NAME $script_name;
    fastcgi_param  PATH_INFO   $path_info;
  }
}

Other deployment options

Refer to http://wsgi.org/wsgi/Servers for a list of some available WSGI servers.

Note

Because of the way Python handles threads in computing heavy applications (like MapProxy WMS is), you should choose a (pre)forking-based server for best performance.

Apache mod_wsgi

If you use Apache then you can integrate MapProxy with mod_wsgi. Read mod_wsgi installation for detailed instructions.

New in version 0.9.1.

mod_wsgi requires a Python script that defines the configured WSGI function as application. You can find an example in config.wsgi.

You need to modify your Apache httpd.conf as follows:

LoadModule wsgi_module modules/mod_wsgi.so

WSGIScriptAlias /mapproxy /path/to/mapproxy/etc/config.wsgi

<Directory /path/to/mapproxy/etc>
Order deny,allow
Allow from all
</Directory>

MultiMapProxy

New in version 0.9.1.

Note

The interface/configuration of MultiMapProxy is not stable yet and might change with future releases.

You can run multiple MapProxy instances (configurations) within one process. You can either manually map URLs to a MapProxy configuration as described in the configuration examples or you can use the MultiMapProxy application.

MultiMapProxy can dynamically load configurations. You can put all configurations into one directory and MapProxy maps each file to a URL: conf/proj1.yaml is available at http://hostname/proj1/.

Each configuration will be loaded on demand and MapProxy caches each loaded instance. The configuration will be reloaded if the file changes.

You can use Paste deploy, as described above, to configure and start MultiMapProxy. The application takes the following options:

config_dir

The directory where MapProxy should look for configurations.

allow_listing

If set to true, MapProxy will list all available configurations at the root URL of your MapProxy. Defaults to false.

Example config.ini:

[app:main]
use = egg:MapProxy#multiapp
config_dir = %(here)s/projects
allow_listing = true