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| Deletions are marked like this. | Additions are marked like this. |
| Line 17: | Line 17: |
| apt-get install apache2 php php-mysql memcached php-memcache php-mcrypt | apt-get install apache2 php php-mysql |
| Line 52: | Line 52: |
| Add this to `/etc/php/7.0/mods-available/memcache.ini`. | Add this to redis configuration file whatever its called .... `/etc/php/7.0/mods-available/memcache.ini`. |
| Line 55: | Line 55: |
| memcache.allow_failover="1" memcache.hash_strategy="consistent" memcache.hash_function="crc32" memcache.session_redundancy=3 memcache.maxreclevel=0 memcache.maxfiles=0 memcache.archivememlim=0 memcache.maxfilesize=0 memcache.maxratio=0 |
something |
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| session.save_handler = memcache session.save_path = "tcp://www01:11211, tcp://www02:11211" }}} Add the IP-address of the webserver to the memcache configurtion in `/etc/memcached.conf`. This will be different for each of the webservers. Make sure there is no space between the comma and the IP-addresses. For www01 it will look like this. {{{ -l 127.0.0.1,192.168.1.52 |
session.save_handler = redis session.save_path = "some redis stuff" |
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| service memcached restart | |
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| == Statistics == | == References == |
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| You can ask memcached for som statistics, by sending it a stats command. {{{ echo 'stats'|nc www01 11211 }}} This will produce something like this. (only 10 first lines are shown). {{{ STAT pid 1696 STAT uptime 1335 STAT time 1581299188 STAT version 1.4.33 STAT libevent 2.0.21-stable STAT pointer_size 64 STAT rusage_user 0.144000 STAT rusage_system 0.204000 STAT curr_connections 2 STAT total_connections 183 }}} == References == |
FIXME! As memcached looses its content e.g cookies on a reboot, we will have to use redis instead!!!
Apache
Running a redundant apache server does not require much from apache itself, but rather the underlying filesystem and a proxy in front of it. The filesystem is important, so the website can be shared between the servers. For this we will use GlusterFS. PHP sessions will have to be shared between the webservers as well and finally we will put a proxy in front of apache, which will be a combination of Corosync and HA-proxy.
In this setup we will configure 2 apache servers. None of these will be master/slave/primary/secondary. They will just be running with the same configuration. Since the servers are configured the same way it makes sense to share some files.
- 192.168.1.51 www (virtual IP-address)
- 192.168.1.52 www01
- 192.168.1.53 www02
Software
apt-get install apache2 php php-mysql
Filesystem
Configure your system as a GlusterFS client, so you have the following in your fstab.
/etc/glusterfs/www.vol /var/www glusterfs defaults,_netdev,rw 0 0
Testpage
Make a simple webpage, that shows something unique about the system. This is usefull when debugging. index.php
1 <?php
2 header('Content-Type: text/plain');
3 session_start();
4 if(!isset($_SESSION['visits']))
5 $_SESSION['visits'] = 0;
6 $_SESSION['visits']++;
7 echo "client: " . $_SERVER['REMOTE_ADDR'] . "\n";
8 echo "server: " . $_SERVER['SERVER_ADDR'] . "\n";
9 echo "hostname: " . gethostname() . "\n";
10 echo "visits: " . $_SESSION['visits'] . "\n";
11 echo "cookie: ";
12 if (array_key_exists('PHPSESSID', $_COOKIE))
13 echo $_COOKIE['PHPSESSID'];
14 echo "\n";
15 ?>
PHP Sessions
Creating a PHP session on one webserver, does not create it on the other. As requests bounces back and forth between the two webservers, this will be a problem for PHP sites. The solution is called memcached.
Add this to redis configuration file whatever its called .... /etc/php/7.0/mods-available/memcache.ini.
something
In /etc/php/7.0/apache2/php.ini and /etc/php/7.0/cli/php.ini find the entry session.save_handler = files and change it to the following.
session.save_handler = redis session.save_path = "some redis stuff"
Copy the configuration to all webservers and finally restart the services.
service apache2 restart
References