Category Archives: Web Hosting

Major Web Hosting software updates – In Flight!

Refuelling an aeroplane while in flight is a major feat of engineering that, despite its complexity, was first carried out way back in June 1923! While this test was successful, mainstream systems to facilitate aerial refuelling didn’t become available until the late 1930s. Then, in Feb/March 1949, Lucky Lady II made the first non-stop around the world flight by refuelling 4 times while in the air.
I had thought that was a great start to a post, until one of my colleagues pointed out that what I’m about to describe is more like changing a wing in mid-flight. Unsurprisingly, a quick Google tells me that hasn’t been done yet (please do comment if I’m wrong!). So that’s where my metaphor crash landed. So, what does it have to do with hosting?

Well, over the past 7 weeks we’ve carried out several major server software updates on our managed Web Hosting service, with only a few minutes of disruption!

We took off by upgrading MySQL, which had recently reached end of life. As well as upgrading, we also made the switch to MariaDB 10. This process did result in a few error pages here and there while the MySQL service was restarted at various stages – let’s call that turbulence – but overall, the flight was very smooth indeed. Following a little tuning and fettling, we quickly started to see the performance benefits, not to mention the all important security updates from running a supported version.

Second, we upgraded Apache and PHP. This was likely to be the most disruptive change given the changes in Apache (though not overly extensive). We wrote our own script to catch and fix any known apache directives that were likely to cause issues. The other potential issue with this upgrade was the possibility of PHP compatibility issues with old code. Thankfully, we have a PHP Selector, from CloudLinux, that allows customers to roll back PHP of their account to a security patched older version. In total, I’ve counted 6 reported issues out of over 450 accounts – all were very simple fixes. I think we can call that a successful landing.

Finally, we switched from cPanel’s EasyApache 3 to their new RPM-Based EasyApache 4. This was where we saw the most overall service disruption. When you consider what the upgrade was doing, that’s no surprise. The process basically had to remove Apache/PHP completely and then reinstall it using a completely different mechanism. Following this automated process, we then had to add our own custom configuration before websites integrated with single sign-on started to function again. Despite how difficult all of that sounds, the whole process was over in a matter of minutes.

I think the moral of the story here is that these very complex upgrades were made to appear trivial because we’re using the right tools for the job. If we were to attempt these manually on a standard LAMP server, each one would have taken considerably longer and would’ve been nigh impossible to accomplish with little or no downtime. We’re using cPanel and CloudLinux, software that has been specifically designed for this purpose.

Further information on what the Web Hosting service offers is available at:

What is Web Hosting?

In early 2012, when I was asked to take over as Service Owner for the Web Hosting service, I asked “What is hosting?”. At the time, I asked that question because I had no knowledge or experience with hosting technology but it’s a question that I’ve come back to a few times in the 4+ years I’ve now been running the service.

The University of Edinburgh has a very large web presence, not just in terms of the main University website,, but we also have a very large number of smaller websites for things like individual business areas, affiliated teaching/research organisations, personal projects/blogs, internal documentation, support tools and the list goes on… As with any website, these need a place to live, therefore Information Services (IS) run an internal Web Hosting service. I like to call it our own little internal version of GoDaddy.

Running such a service within a higher education institution can be challenging given the wide variety of use-cases and skill levels within our very diverse user community. So, focusing on our very successful Linux-based side of the service, I thought I would share some of my experience so far and some details of what we’ve done with the service over the past few years. I’ve split those into a few themes; Consolidation, Technology, Security and Usability and we’ll publish this Behemoth blog post in 2 parts.


One of the biggest misconceptions about a web hosting service is that it basically runs itself. Technically, that’s true – A server will run, run and run if you don’t interfere with it. What about security updates, improvements, and new technology though? That’s not to say hosting needs the same constant attention as a huge business-critical application, like MyEd (our student/staff portal) but it still needs to be maintained and improved regularly. The result of that sort of misconception is when time and resources get tight, hosting is the kind of service that finds itself on a back burner while resources need to be focussed on the higher priority services.

Back in 2012, we had a number of Unix & Linux servers that fell under the umbrella of the hosting service, around 7 in total (including DR and Test servers). These were all running different technology and had very different use cases. Five of these were inherited from other places in IS as part of restructures. The other two were newer machines that had been brought in to replace those 5 – but never had.

The first challenge then, was to consolidate all of the websites running on these servers onto one ‘standard’Screen Shot 2016-05-30 at 13.07.14 platform (more on that platform later). This painstaking activity was carried out manually, auditing every website we hosted and migrating it where required. We had a great deal of help from the web teams in various areas around the university who made use of the service. The most complicated opponent, deserving of a mention, was Morse – a server running websites dating back to when brand new episodes starring the famed detective of the same name, and his beautiful Jag Mk2, were on TV. The process has taken the last four years, with the final few websites due to be migrated in the coming few weeks. Those 7 machines have been replaced with 5 new servers, each identical to the next.

I can hear the questions already. “Five? That’s not much of a decrease!” Ah, Those 5 machines though, are hosting nearly twice as many websites as the 7 old rickety servers did 4 years ago. Most are resource intensive database-driven sites. We also have plenty of capacity for growth.

As part of the migration process, we devolved reseller rights to the various business areas and web teams throughout the organisation who use the service. This lets them create/edit/delete hosting accounts to suit themselves, making things much faster for them and reducing the workload on our team, giving us more time to spend on service improvement.


Now for the interesting part, the techy stuff. I would have been heard in meetings four years ago saying phrases like “out of date”, “unreliable” and “not fit for purpose”. Don’t think I need to go into much more details on that. So, when faced with the option of whether to upgrade the existing (newer) servers, I decided resources were better focused on designing and building an entirely new service. That brings me back to my initial question, “What is hosting?”.

I mentioned above that we have a wide variety of use cases, from standard blogs to content proxied into central services to feeds driving LCD displays in certain schools, we host it all. Needless to say we had issues with resource contention, issues with security and issues with compatibility. There was talk of setting ‘rules’ for what was and wasn’t allowed on the service but I disagreed because my answer to the question of what web hosting is: a service where people can host *anything they like* provided the technology can support it. Enter cPanel and CloudLinux.


cPanel is the web hosting management platform that everyone knows. It does everything for you other than make your coffee in the morning. You define a set of hosting packages then simply start provisioning accounts. cPanel takes care of Apache and PHP, MySQL, SSH, right down to access permissions, etc. It has a great intuitive UI that allows site owners to manage their own hosting and makes it nice and easy for us service managers to provision accounts. We were even able to write our own ‘hooks’ to carry out custom tasks triggered by cPanel events/actions.

CloudLinux is where things get very impressive though, a CentOS-based Linux distribution designed specifically for shared hosting. Anyone familiar with shared hosting will know that resource contention is one of the biggest issues we face, individual sites using too much of the server’s available resource. On a shared server, one small site doing something silly or being the innocent victim of a DDoS attack can bring down the entire server. CloudLinux limits individual users’ use of the shared resources to prevent that from happening. That includes; CPU %, Processes, IO, RAM and even MaxClients. As if that wasn’t impressive enough, they have something called CageFS (caged filesystem). CageFS puts each user in their own ‘cage’ which isolates them from all other users and the system files that they shouldn’t be able to see. It also adds the ability to let users choose the version of PHP they want to run and more recently adds support for Python and Ruby.


So there you have it, looking at all of the above. We’ve given users a service where they can run pretty much anything without worrying about any negative impact on the service itself or any of the other customers’ applications/websites.

Part 2 coming soon…