Feeds

Continuous delivery: What works (and what doesn't)

Software on the assembly line

Top three mobile application threats

Featured on Facebook

So who does continuous delivery and where does it work well? It is said that Facebook deploys it at least a couple of times (or more) a day with its “ship early and ship often” intonation; it therefore delivers continuously to facilitate this dynamism.

With a web-facing front end and a cloud-located back end, this is fine for Facebook. Users wouldn’t notice a new delivery any more than they would a page refresh. Outside the web application the process is slightly more involved.

“Continuous delivery is sometimes confused with continuous deployment. But continuous deployment means that every change goes through the pipeline and automatically gets put into production, resulting in many production deployments every day,” says Fowler.

“Continuous delivery just means that you are able to do frequent deployments but may choose not to do it, usually due to businesses preferring a slower rate of deployment. In order to do continuous deployment you must be doing continuous delivery.”

The trouble is that it works beautifully on paper, but the applied science may be somewhat less exact

The trouble with continuous delivery thus explained is that it works beautifully on paper, but the applied science may be somewhat less precise. Not everything is as easily automated as might be hoped.

For example building an integration or staging test platform that closely emulates a real production environment is probably not a trivial task. Databases have to be built and populated, licences for software installed and so on.

Mark Warren, European marketing director at Perforce, warns that the tests may take longer to execute than the cycle time between deliveries from development. Imagine the backing up of cream cakes from the production plant if the conveyor belt through quality control is running at only a tenth of the speed – it will get messy quickly.

“There are scenarios where automation is desirable, such as a front-end social network platform where the cost of continuous updates may be low and impact of failure cheap,” says Warren.

“However for a back-end payment processing system that needs the same level of availability as the national electricity grid, changes must be deployed less frequently. In highly secure environments, such as payment handling, there may need to be an air-gap between development and production systems.

“Someone will need to walk the floppy disk across the room. Where manual steps are required, the process and recording of progress has to fill the gap.”

Repeat after me

In some respects the most common continuous delivery pipelines are not all that different from traditional waterfall processes. In Continuous Delivery, the de facto Bible on the topic by Jez Humble and David Farley, you will find images of the lifecycle that include familiar phases such as “user acceptance testing”.

The difference is that there is a lot more automation so the process can execute more rapidly and can be repeated at will.

From Warren’s perspective inside Perforce, a company marked out for its distributed versioning service, automation depends on a couple of key capabilities: some kind of tooling that enables fast, predictable and cross-platform scripting and a single repository or “single source of truth”.

“The scripting angle is pretty well covered with tools like Puppet, Chef and a few commercial offerings. The single-source-of-truth repository is effectively the version management system (the production plant) that software developers are used to, but now there are additional demands on its performance,” says Warren.

Notably, this version management system needs to be able to version everything – not just source code but also the “entire build, test and deploy environment job, and possibly the built executables too”.

Warren concludes: “If multiple-version management tools are in use, the complexity involved in ensuring a consistent and whole deployment is hugely increased. If it can’t handle, say, large binary files as well as small JavaScript source, then there is no guarantee as to what is being deployed at any point.”

Where do we stand in 2013? We can say with some certainty that the shadow of cloud, mobile and web-facing applications on every corner dictates an increased need for continuously delivered rapid application development and deployment.

So why isn’t continuous delivery more prevalent across the common vernacular of tech?

It will be, trust us on that one. ®

Maximizing your infrastructure through virtualization

More from The Register

next story
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Captain Kirk sets phaser to SLAUGHTER after trying new Facebook app
William Shatner less-than-impressed by Zuck's celebrity-only app
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Apple fanbois SCREAM as update BRICKS their Macbook Airs
Ragegasm spills over as firmware upgrade kills machines
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
EU dons gloves, pokes Google's deals with Android mobe makers
El Reg cops a squint at investigatory letters
Chrome browser has been DRAINING PC batteries for YEARS
Google is only now fixing ancient, energy-sapping bug
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.