Continuous Deployment in Perl: Code & Folks

pre-reviewed version, published in a Perl issue in the Software Developer's Journal (May 2012 issue)

This article was written together with my friend Pierre-Antoine Queloz (paqueloz@gmail.com)

Continuous Integration is the tactic of decreasing the latency between the implementation of a new piece of code and its integration in the overall project. It is the backbone of Continuous Deployment that is often defined as releasing software very frequently in order to satisfy customer needs and get their feedback as soon as possible. Both have shown their benefits and play an important role in the success of the current Agile software development trend.

Comparing hostip and geoip

What is the best IP address to geolocalisation system?

Seeking to analyze web log files by the country of request origin, I recently proposed a simple plugin wrapping hostip.info API. Of course, the major competitor in the field is maxmind geoip and they provide a free light version of their database. This database can be queried through their java API of a geoip Grails plugin.

Time has come for numbers. How each module perform on the same set of ip address? Even with 3% of uncertainties, maxmind geoip lite shows to be clearly the best.

hostip grails plugin: from IP address to localisation

Getting a localisation from an IP address is somehow straight forwards with available web services. However, for massive report (such as analyzing web logs from the remoteIP perspective), it is not doable, even with caching.
The idea of the plugin is to use the free distributed hostip database, mirror it locally and give a Grails service to query it.
There is another post, comparing hostip with maxmind geoip. It should certainly be read before jumping to hostip.

Perl & Hudson: continuous testing & deployment

One of the key point of Agile driven development is an infrastructure to seamlessly build, test and deploy the software at every commit.

Although lot of framework exists in the Java world, there is less available pointers on this topic with Perl. The aim of this post if to give a few practical hints on how we set up our continuous testing and deployment system using Husdon for multiple, dependent perl distributions.

Be ready, it's easy!

A Perl URL checker

URL::Check : yet another URL check system
You want to get notified is something goes weird on a web site you develop and that should be running 24/7?
Given a list of url, you want to check if they exist and send receive an email in case of trouble.
The problem is so common and hundreds of solutions exists on the web, from simple crontab shell to more complex system (hyperic & co).
We propose here one more system. The constraints were:

• check availability of url, response time or contents,
• get email to be notified in case of failure,
• a simple configuration system.

A Grails GSP template caching system

Caching a whole rendered page is not always the best options, because some minor parts of the page can change from one user to another (e.g. login info).
In other situations, different perspectives can have common components and caching them can dramatically reduce page rendering time (typically a search results).
Inspired from the very good UiPerformance and springcache and based on ehCache, we propose an idea to go a bit further and cache either template rendering or a piece of gsp.

A Grails template rendering profiler

A complex grails page if often a cascade of templates rendering, nested in each others.
Optimizing page views starts with profiling which template takes time and which template is called by which one.
We offer a capture mechanism of all calls and several rendering: call stack, template time summary, and a visual display of the call graph.