The Apache configuration you find here enables server plugins :
<VirtualHost *:80>
ServerAdmin webmaster@localhost
DocumentRoot /var/www/html
ErrorLog ${APACHE_LOG_DIR}/qgis-server-error.log
CustomLog ${APACHE_LOG_DIR}/qgis-server-access.log combined
# Longer timeout for WPS... default = 40
FcgidIOTimeout 120
FcgidInitialEnv LC_ALL "en_US.UTF-8"
FcgidInitialEnv PYTHONIOENCODING UTF-8
FcgidInitialEnv LANG "en_US.UTF-8"
FcgidInitialEnv QGIS_DEBUG 1
FcgidInitialEnv QGIS_SERVER_LOG_FILE /tmp/qgis-000.log
FcgidInitialEnv QGIS_SERVER_LOG_LEVEL 0
FcgidInitialEnv QGIS_PLUGINPATH "/opt/qgis-server/plugins"
# Needed for QGIS HelloServer plugin HTTP BASIC auth
<IfModule mod_fcgid.c>
RewriteEngine on
RewriteCond %{HTTP:Authorization} .
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
</IfModule>
ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
<Directory "/usr/lib/cgi-bin">
AllowOverride All
Options +ExecCGI -MultiViews +FollowSymLinks
# for apache2 > 2.4
Require all granted
#Allow from all
</Directory>
</VirtualHost>
You can comment out this line to disable plugins :
#FcgidInitialEnv QGIS_PLUGINPATH "/opt/qgis-server/plugins"
And comment out this part if you use plugins but not the HelloServer one :
# Needed for QGIS HelloServer plugin HTTP BASIC auth
#<IfModule mod_fcgid.c>
# RewriteEngine on
# RewriteCond %{HTTP:Authorization} .
# RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
#</IfModule>