Documentation: Update documentation regarding the Redis requirement - refs #6858

Author: ywarnier

public/documentation/installation_guide.html

@@ -96,7 +96,7 @@ <h3>2.5. Installation wizard</h3>
 
     <h3>2.6. Sessions and Redis</h3>
     <a id="web-install-sessions" class="anchor"></a>
-      In this beta version, there are known issues with sessions not getting updated fast enough, which can be solved (temporarily) by using a Redis server. Check the command line instructions for more about this. This is a temporary situation that we expect to fix before the stable release.
+      Redis is an in-memory non-relational database server that can be used to manage PHP sessions. Under high loads, PHP sessions management can be a bottleneck. Using Redis can considerably alleviate that bottleneck but should not be an issue for low to moderate uses (up to 10 *simultaneous* users or so). Check the command line instructions for more about this.
 
     <h3>2.7. Clean up</h3>h3>
     <a id="web-cleanup" class="anchor"></a>
@@ -111,18 +111,22 @@ <h2>3. Command line installation</h2>
 
     <h3>3.1. Software stack</h3>
     <a id="cli-install-stack" class="anchor"></a>
-<p>Assuming you are using a dedicated Ubuntu 24.04 LTS, these commands should help you have the software stack installed in a breeze. Otherwise, please review the requirements above and make sure they are met before moving on to the next section.</p>
+<p>
+    Assuming you are using a dedicated Ubuntu 24.04 LTS, these commands should help you have the software stack installed in a breeze.
+    Otherwise, please review the requirements above and make sure they are met before moving on to the next section.
+    Please note Redis is optional. It is included for efficiency reasons for self-managed servers, but can be skipped on shared hosting.
+</p>
 <pre>
 sudo -s
 apt update && apt -y upgrade
 apt -y install apache2 libapache2-mod-php8.3 mariadb-client mariadb-server redis-server php8.3-{apcu,bcmath,curl,exif,gd,iconv,intl,ldap,mbstring,mysql,opcache,soap,xml,zip,redis}
 a2enmod rewrite
 cd /var/www/
 mkdir chamilo
-wget https://github.com/chamilo/chamilo-lms/releases/download/v2.0.0-beta.1/chamilo2.0.0-beta.1.tar.gz
+wget https://github.com/chamilo/chamilo-lms/releases/download/v2.0.0-rc.1/chamilo2.0.0-rc.1.tar.gz
 # about 400MB
-tar zxf chamilo2.0.0-beta.1.tar.gz
-rm chamilo2.0.0-beta.1.tar.gz
+tar zxf chamilo2.0.0-rc.1.tar.gz
+rm chamilo2.0.0-rc.1.tar.gz
 cd chamilo
 touch .env
 chown -R www-data: var/ config/ .env
@@ -156,6 +160,7 @@ <h3>3.3. Web server</h3>
 Here is an example Apache vhost configuration file for an installation on the http://my.chamilo.local/ URL (replace all values between brackets, including the brackets, to your custom values).<br>
 It includes PHP settings which will only affect this vhost. If you prefer to set those PHP settings in php.ini, you are welcome to do so.<br>
 We also assume you will be using a default Redis installation to manage sessions (see notes in the web panel install section).<br>
+Reminder: Redis is optional. If you don't use it, do not use the lines about "session.save_handler" and "session.save_path" below.<br>
   <pre>
 cd /etc/apache2/sites-available
 vim [my.chamilo.local].conf
@@ -478,7 +483,7 @@ <h3>6.5. Redis</h3>
       want to install the PHP Redis extension from the official PHP website, for example (adapt PHP and Redis version numbers)
       https://downloads.php.net/~windows/pecl/releases/redis/6.*.*/php_redis-6.*.*-8.3-ts-vs16-x64.zip
 
-      This is not necessary to install Chamilo (so you can do it afterwards or never at all if you don't experience session issues).
+      This is not necessary to install Chamilo (so you can do it afterwards or never do it at all if you don't experience session issues).
 
       Download, unzip and place the .dll file into C:\wamp64\bin\php\php8.3.*\ext\
       then add "extension=php_redis.dll" at the end of C:\wamp64\bin\php\php8.3.*\php.ini
@@ -501,7 +506,7 @@ <h3>6.5. Redis</h3>
 </pre>
 
       Inside your WampServer configuration, in the httpd-vhosts.conf file,
-      add the following lines *inside* the &lt;VirtualHost&gt; tag:
+      add the following lines *inside* the &lt;VirtualHost&gt; tag (only if you use Redis):
 <pre>
     php_admin_value session.save_handler "redis"
     php_admin_value session.save_path "tcp://192.168.1.100:6379"

public/documentation/optimization.html

@@ -23,8 +23,8 @@ <h2>Avoid dev mode</h2>
   <h2>Sessions</h2>
   Chamilo 2 uses sessions to store user data between requests. Sessions are stored on disk by default.<br>
   In comparison with Chamilo 1, Chamilo 2 uses many micro-service-type calls to retrieve data from the system and repaint parts of the pages as the underlying data changes.<br>
-  This has the damaging effect of requiring much more accesses to the session files, which can slow down the system significantly or generate losses of session (the system acting as if you are not logged in).<br>
-  To remove this impact, make sure you use a system to store sessions that will have a very small footprint and be able to manage session accesses very quickly (Redis, Memcached, etc.). This is described in the installation guide.
+  This has the negative effect of requiring much more accesses to the session files, which can slow down the system significantly or generate losses of session (the system acting as if you are not logged in).<br>
+  To remove this impact, make sure you use a system to store sessions that will have a very small footprint and be able to manage session accesses very quickly (Redis is likely the best solution here). This is described in the installation guide.
 
   <h2>Database</h2>
   Chamilo 2 uses a database to store most of its data (except for files). This means the database is very commonly used and can be a bottleneck in some cases.<br>