Recently by Richard Benson

We use Pingdom a lot here; we have 65 checks running at the moment, we publish our uptime reports for the most important ones, and we have our own-made Pingdom status screen up in the main office but we all miss the old Desktop Notifier.  This died when Pingdom deprecated their v1 API and it seemed that neither they, nor the community, were going to provide a replacement any time soon, so here is ours; "Desktop Notifier for Pingdom".

The EU Directive on Privacy and Electronic Communications initially caused quite a stir 12 months ago, but the UK's Information Commissioner's Officestepped in and said that UK firms would have a year to comply with the regulations.  That year is up on 26th May and people are starting to talk about the EU Cookie Law again, however no-one seems to be exactly sure what the implications will be and the ICO is not offering answers to the questions people are asking.

Debian 5 (Lenny) is now out of support it will not be receiving any more security or bug fix updates, meaning an upgrade to 6 (Squeeze) is required.  The procedure is reasonably simple, however if you are using Lenny on a Rackspace Cloud server, you will get an error relating to "dependency based startup".  Furthermore, if you are using MySQL 5, you will need to upgrade that to 5.1 and this itself has a pitfall if you have based your config on the stock my.cnf.  Below is the procedure for upgrading Debian Lenny to Squeeze on Rackspace Cloud with MySQL installed.

Google recently announced that they are expanding their use of SSL encryption to more local domains around the globe in an effort to "increase the privacy and security of your web searches".  Whilst this seems a noble intention, it will affect every site owner that uses a stats package such as Google Analytics or Piwik and those sites that use keyword data to enhance the user experience for their visitors.

Travel Butlers provide tailored holiday packages in South Africa and the neighbouring countries.  Traditionally their website development had been done in-house but they needed some advanced Google Maps API programming to push their site forward and make the experience for their customers that little bit better.

Often when using the command prompt in Windows Vista and Windows 7 you'll need to run the command as an Administrator and whilst running a command prompt elevated is not tough, it's fiddly. If you've forgotten to do it before you've moved your way around the file system it can be very annoying.

sudo <your-command> <arguments>

Before embarking on a MySQL Cluster installation, it is important to remember that MySQL Cluster is 'just' a storage engine for your existing MySQL database servers.  It stores data at the table level, not the whole database, it is therefore on the same functional level as MyISAM or INNODB.  You still need a standard MySQL server to access the table data and store the database information.  This has the fringe benefit that you can target specific tables to be saved to the cluster, rather than the whole database, if you have some tables that are either more important, or more heavily used.

In this article we are going to cover MySQL Cluster, it's installation on Debian (Lenny), Master-Master replication and how to tie all this together with HAProxy for a very high availability solution.

NB: At present you cannot request or share additional internal IP addresses with Rackspace Cloud, so you are going to have to use the external addresses.  With large databases this will incur additional bandwidth charges, be sure to evaluate this additional cost against the benefits provided by high availability.  When Rackspace allow the allocation of additional internal IPs, this article will be updated to reflect that.

To go with our Load Balanced Web Cluster, which provides good availability for your web services, providing high availability for your database is also likely to be an important requirement.  In most modern web apps, there's not much use having your webservers available constantly if your database is down.

There are a number of solutions to this with MySQL and every situation will require a different response, there are a lot of good articles out there to help you decide which solution is best. In this article we will be covering MySQL Master-Master replication and installation on Debian (Lenny) using Rackspace Cloud Servers.

The standard model of MySQL replication is a single master with multiple slaves, which provides you with very good read reliability, but writes can only be made to the master node.  This means that if the master fails, you can't just switch to another node and carry on as before, your slaves will become out of sync.  Additionally you can't load balance between your nodes for reads and writes.  By using a multiple master configuration, you can drop a node at any point and either switch your connection string to using the remaining master, or use load balancing and failover with HAProxy.

Upon creation, most Rackspace Cloud Servers have a completely open firewall policy that will allow any computer into any port on your machine.  Linux uses IPTables to firewall connections into and out of your server but needs a fair amount of configuration to get it working and for it to stay working on a reboot.

In this article we will cover basic saving and loading of IPTables rules in Debian/Ubuntu on shutdown and boot up as well as common rules that go with our other guides.