In T154558 several changes to Piwik were performed manually to mitigate various problems:
* SET GLOBAL max_connections 300 to the mysql instance (apache error logs for no more connections to use)
* disabled apache mod_deflate (probably this one wasn't needed)
* set `bulk_requests_use_transaction=0` to /etc/piwik/global.ini.php (https://github.com/piwik/piwik/issues/6398#issuecomment-91093146) that was causing entries in the apache error log for locks already in use.
* Bump the maximum Apache connections allowed (hence the number of processes due to mpm_prefork) from 150 to 250, reducing also the churn due to process kill/re-spawn with MaxSpareServers set to 150 as well (and Min to 50):
```
# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# MaxRequestWorkers: maximum number of server processes allowed to start
# MaxConnectionsPerChild: maximum number of requests a server process serves
<IfModule mpm_prefork_module>
# prev: 5
StartServers 250
# prev: 5
MinSpareServers 50
# prev: 10
MaxSpareServers 250
# prev: 150
MaxRequestWorkers 250
MaxConnectionsPerChild 0
</IfModule>
# vim: syntax=apache ts=4 sw=4 sts=4 sr noet
```
What would be needed:
1) Puppetization of the mysql instance and related settings (investigate the use of thread_pools if mariadb is chosen).
2) Puppetization of the above fixes.
3) Refactor of piwik's role code into modules and profile for a better maintenance over time.
Security upgrades will be handled in T158322