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FastCGI on Apache

Using mod_fastcgi

You'll need to enable mod_fastcgi first for Apache. In most cases, this is done by linking the module's configuration file fastcgi.conf from mods-available to mods-enabled (this can be done with a2enmod on Debian and Ubuntu).

Next you need to modify the configuation file:

<IfModule mod_fastcgi.c>
  AddHandler fastcgi-script .wt
  FastCgiIpcDir /var/lib/apache2/fastcgi
  FastCgiConfig -idle-timeout 100 -maxClassProcesses 1 -initial-env WT_APP_ROOT=/tmp
</IfModule>

This will automatically start any file ending with .wt as a FastCGI executable. You can also use "external CGIs", which allow you to control in more detail how a single application gets started (and restarted):

  FastCgiExternalServer /var/www/wt-examples/simplechat/simplechat.wt -host localhost:9091 -idle-timeout 200

For this latter deployment option, you need to use the FastCGI utility cgi-fcgi to run the Wt application independent of the web server. When a request for the application is received by the web server, it is forwarded to your FastCGI application using the FastCGI protocol over the given TCP connection.

The only thing left to do is enable CGI execution in your Apache configuration (see below).

Using mod_fcgid

You'll need to enable mod_fcgid first for Apache. In most cases, this is done by linking the module's configuration file fcgid.conf from mods-available to mods-enabled (this can be done by running a2enmod.

Next you need to modify the configuration file:

<IfModule mod_fcgid.c>
  AddHandler fcgid-script .wt
  SocketPath /var/lib/apache2/fcgid/sock
  IdleTimeout -1
  ProcessLifeTime -1
  MaxProcessCount 10
  DefaultMaxClassProcessCount 10
  DefaultMinClassProcessCount 1
</IfModule>

and then do this command:

    chown www-data:www-data /var/run/wt -R

Enabling CGI in Apache

Next, we create a new "site" configuration file for Wt applications: /etc/apache2/sites-available/wt which we will install in /var/www/wt (this must be a directory within your docroot):

<Directory /var/www/wt/>
  #Order Deny,Allow
  Allow from all
  # Enable CGIs to be executed 
  Options ExecCGI
</Directory>

Then, we need to create folder /var/run/wt and to give the Apache server write permissions to that directory.

Next I enable the site and reload Apache:

    a2ensite wt
    /etc/init.d/apache2 reload

If it does not work

You may need to create a run directory with the proper permissions:

sudo mkdir /var/run/wt
sudo chown www-data:www-data /var/run/wt -R

Verify that you have at least two threads configured in /etc/wt/wt_config.xml:

<num-threads>2</num-threads>

Ensure yourself that your wt application is linked against libwtfcgi instead of libwthttpd. E.g. in your own CMakeLists.txt, write

target_link_libraries(hello.wt wt wtfcgi .......)

or for the examples included with Wt, set EXAMPLES_CONNECTOR to wtfcgi:

cmake -DEXAMPLES_CONNECTOR="wtfcgi"

Look for errors in your apache error log. Especially if you see wt complaining about 'stat' and 'docroot not being set', this means that your executable is linked to wthttpd instead of wtfastcgi; in this case you need to fix your linker options first.

Updated by Roel Standaert almost 3 years ago ยท 6 revisions