Continuous Delivery Workshop with Neal Ford (@neal4d) – a Retrospective

I attended a workshop at DevWeek 2012 led by Neal Ford (@neal4d) on Continuous Delivery (CD). The day was excellent – Neal is a really engaging presenter – and I took copious notes, even though I’d already read most of the CD book. Fifteen months later, I thought it would be interesting to see how my notes from Neal’s workshop compared with my experience of Continuous Delivery, both within my job at thetrainline.com, and also in conversations with other people, particularly the good folks in the London Continuous Delivery meetup group.

The tl;dr version: go attend one of Neal’s excellent CD workshops, but be prepared for the challenges with Continuous Delivery to be much more social/organisational than technical.

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Tune logging levels in Production without recompiling code

IAP Software Development Practice JournalThis article first appeared in Software Development Practice, Issue 1, published by IAP (ISSN 2050-1455) 

Abstract

When raising log events in code it can be difficult to choose a severity level (such as Error, Warning, etc.) which will be appropriate for Production; moreover, the severity of an event type may need to be changed after the application has been deployed based on experience of running the application. Different environments (Development (Dev), User Acceptance Testing (UAT), Non-Functional Testing (NFT), Production, etc.) may also require different severity levels for testing purposes. We do not want to recompile an application just to change log severity levels; therefore, the severity level of all events should be configurable for each application or component, and be decoupled from event-raising code, allowing us to tune the severity without recompiling the code.

A simple way to achieve this power and flexibility is to define a set of known event IDs by using a sparse enumeration (enum in C#, Java, and C++), combined with event-ID-to-severity mappings contained in application configuration, allowing the event to be logged with the appropriate configured severity, and for the severity to be changed easily after deployment.

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GOOS at 7digital – Code Shapes, the Purpose of Tests, and Logging Done Well

I recently went to a Devs in the ‘Ditch meetup at 7digital to hear Chris O’Dell (@ChrisAnnODell) explain 7digital’s journey to Continuous Delivery and Steve Freeman (@sf105) speak on GOOS and system testing. We had some useful discussions on dependency injection and how to use logging well, and Steve’s perspectives on ‘code shapes’ and the purpose of tests were revealing.

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Moving a News Website to a Different Content Management System

How does a small but nationally visible non-profit organisation go about moving their news-focused website to a different content management system? A good friend of mine works for a non-profit news organisation and asked me this question recently, so I put together some very brief notes based on some of the website migrations I have done over the last few years for similar organisations (a charity, an industry trade body, and a specialist news publisher).

moving books

The client being a small non-profit organisation constrains the solution to license-free (non-commercial) content management system (CMS), because at an industry standard of around $20k and upwards, the license costs for commercial CMS products tend to be out of the range of small non-profit budgets.

There are therefore five key things to consider for migrating an existing news-focused website for a non-profit organisation to a new CMS:

  1. What open-source technology should you use?
  2. To what extent should you customise the technology and how?
  3. What is a reasonable cost – one-off and ongoing support?
  4. Who should undertake the implementation?
  5. Where should the site be hosted?

There are plenty of other problems to solve once the initial decisions have been taken, but for a simple, news-focused website, with content only in English, we don’t need to worry about managing translations or dealing with transactional workflows. So what’s next?

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Avoiding Legacy with Deployment Automation and Infrastructure-as-Code

Learning from ‘Working Effectively with Legacy Code’ by Michael C. Feathers

Legacy Code (cover)

Working Effectively with Legacy Code by Michael C. Feathers is a classic software development text. Not only is it still completely relevant when working with code, seven years after it was published, but also the approaches it advocates at the source code level are becoming essential to apply at the component and system integration levels too as our software systems become more complicated and polyglot, and we learn to fully automate our deployments and treat our infrastructure as code.

For an overview of the book itself, read my review of ‘Legacy Code’ on Amazon.co.uk. I describe the different sections and how each is useful in a particular context. The rest of this article will focus on other aspects of Legacy Code, particularly the ‘why’ of changing code, and the implications for Continuous Delivery, infrastructure-as-code, and deployment automation.

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