{{tag>en en:linux en:server en:web}}
====== Apache Configuration ======

This page describe how to configure a website with [[en:linux:serveur_web|Apache]].

===== Structure =====
A configuration file for Apache use a structure, for example :
<code apache>
<VirtualHost *:80>
        Servername www.bouthors.fr
        ServerAdmin matthieu@bouthors.fr

        DocumentRoot /var/www
        <Directory />
                Options FollowSymLinks
                AllowOverride None

        </Directory>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
                RedirectMatch ^/$ /wiki/
        </Directory>
</VirtualHost>
</code>

Is this example, the tags are VirtualHost and Directory, and each section contains several options like "Servername", "DocumentRoot", "Options", "allow", ... 

Common tags are :
  * <VirtualHost> defines virtual hosting
  * <Directory> defines directives for a folder on the file system
  * <Location> defines directives based on the url path


===== Pulish a folder =====
The first step is to link the file system to an url path with one of the following way :
  * DocumentRoot allows to map the root url "/", for example :
<code apache>
  DocumentRoot /var/www
</code>
  * Alias allows to map a part of the webserver, for example "/wiki" :
<code apache>
  Alias /wiki /opt/dokuwiki
</code>

Then, the requests have to be autorized with the following options:
  * Allow allows requests based on IP, DNS or a variable
  * Deny denies requests based on IP, DNS or a variable
  * Order defines precedence between "allow" and "deny" options, if a request match both "allow" and "deny" :
    * Order Allow,Deny will deny the request
    * Order Deny,Allow will allow the request

Complete example :
<code apache>
  Alias /wiki /opt/dokuwiki
  <Directory /opt/dokuwiki>
    allow from all
    Order deny,allow
  </Directory>
</code>

Apache also allows additional parameters with "option" which can have several values :
  * None : no options
  * All : all features except MultiViews
  * ExecCGI : allows CGI exectution
  * FollowSymLinks : allows to access symbolic links\\ The destination of the link must be readable by Apache, be carefull with the security.\\ This option is not available with <Location>
  * Includes : allows "Includes"
  * IncludesNOEXEC : allows "Includes" but will disable functions #exec cmd and #exec cgi
  * Indexes : allows directory listing
  * MultiViews : allows the use of mod_negociation
  * SymLinksIfOwnerMatch : similar to FollowSymlinks but only allows links with the same owner

Example with symbolic link authorization  :
<code apache>
  Alias /wiki /opt/dokuwiki
  <Directory /opt/dokuwiki>
    Options FollowSymLinks
    allow from all
    Order deny,allow
  </Directory>
</code>

It is possible to use "+ and "-" to define modification from inherited options. For example to add directory listing to a subfolder (without removing other options) :
<code apache>
  <Directory /opt/dokuwiki/share>
    Options +Indexes
  </Directory>
</code>

Finally, it is possible to change the options with ".htaccess" files located directly on the file system. To allow the use of ".htaccess", the option "AllowOverride" must be defined. For example :
<code apache>
Alias /wiki /opt/dokuwiki
<Directory /opt/dokuwiki/>
        Options +FollowSymLinks
        AllowOverride All
        order allow,deny
        allow from all
</Directory>
</code>
.htaccess example which deny all access to the folder :
<code apache>
order allow,deny
deny from all
</code>

Note : it is possible to apply options based on url path instead of file system with the tag <Location> instead of <Directory>.

===== Customization =====
It is possible to customize the server with the following options :

  * ServerAdmin defines the email displayed in error messages
  * ServerSignature defines the signature displayed on server generated pages

Example :
<code apache> 
        ServerAdmin matthieu@bouthors.fr
</code>


===== Virtual hosting, redirects and reverse proxy =====
Apache has several useful features :
  * Virtual hosting used to host several websites on a single public IP
  * redirecting users to another url, also used to redirect the root to another part of a site
  * rewriting with reverse proxy to forwarding the request to another server

==== Virtual hosting ====
Hosting of several websites  :
  * NameVirtualHost defines which IP are hosting virtual hosts
  * <VirtualHost> defines a virtual host
  * ServerName defines the hostname of the current <VirtualHost>
  * ServerAlias allows to define additional hostnames

For example to host www.bouthors.fr and web3.bouthors.fr on the same Apache with two different configurations :
<code apache>
<VirtualHost *:80>
        ServerName www.bouthors.fr
        ServerAlias ipv6.bouthors.fr
        DocumentRoot /var/www
        
        ...
        
</VirtualHost>
<VirtualHost *:80>
        ServerName web3.bouthors.fr
        DocumentRoot /var/www
        
        ...
        
</VirtualHost>
</code>
==== Redirects ====
Redirects are often used, they allow to ask the user to request another url.

Options used are :
  * Redirect redirect all requests to another URL. This directive map a path to a new path.
  * RedirectMatch redirect requests matching a regex


Example with the redirection of the root only :
<code apache>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
                RedirectMatch ^/$ /wiki/
        </Directory>
</code>

Example with the redirection of all requests  :
<code apache>
<VirtualHost *:80>
        RedirectMatch 301 ^/(.*) http://www.bouthors.fr/$1

</VirtualHost>
</code>

==== Reverse Proxy ====
Apache can also become a reverse proxy and forward requests to other web servers. In this case, mod-proxy module is used.

First, mod-proxy needs to be enabled :
<code>
# a2enmod proxy_http
Considering dependency proxy for proxy_http:
Enabling module proxy.
Enabling module proxy_http.
Run '/etc/init.d/apache2 restart' to activate new configuration!
# /etc/init.d/apache2 restart
</code>

Then the ProxyPass command must be used. For example, to redirect /wiki to the server "web4"  :
<code apache>
ProxyPass /wiki/ http://web4.bouthors.fr/wiki/
</code>

===== Additional parameters =====

==== Include ====
Include is used to insert another configuration file.

Example (end of apache2.conf) :
<code apache>
# Include generic snippets of statements
Include conf.d/

# Include the virtual host configurations:
Include sites-enabled/
</code>

==== PHP Configuration ====

Inside ///etc/php5/apache2/php.ini// to configure the maximum upload size :
  upload_max_filesize = 15M

To change the maximum post size :
  post_max_size = 8M

If you need a lot of memory, change memory_limit :
  memory_limit = 128M


==== Log ====
Logs can be controled by different ways :
  * CustomLog : defines the log name and log format
  * ErrorLog : defines where error logs are sent
  * LogLevel : defines the level of verbosity


Example : 
<code apache>
       ErrorLog ${APACHE_LOG_DIR}/error.log

        # Possible values include: debug, info, notice, warn, error, crit,
        # alert, emerg.
        LogLevel warn

        CustomLog ${APACHE_LOG_DIR}/access.log combined
</code>

==== Charset Encoding ====
The file ///etc/apache2/conf.d/charset// defines the Content-Type used by Apache.

By default, UTF8 is used :
<file>
AddDefaultCharset UTF-8
</file>

To use ISO instead, the following option can be used :
<file>
AddDefaultCharset ISO-8859-15
</file>

===== Links =====
  * [[en:linux:serveur_web]]