Chris was recently at the Agile on the Beach 2015 conference, and this Friday he reported back to the rest of the dev team on some of the talks that he went to there.
The death of continuous integration
Steve Smith talked about “the death of continuous integration” – CI is a cultural thing, not just Jenkins. The key questions are: whether everyone commits something to trunk every day, and whether problems in the build get fixed quickly. He described two build models – synchronous and asynchronous – the former is waiting for the build to complete before continuing, and the latter is allowing the build to continue, and swapping back if the build breaks.
He discussed three branching models:
* “Long lived feature branches” – these are generally a nightmare.
* “Short-lived feature branches” – fine if everything works as it should, but reviewers aren’t always available immediately, and you might need to switch context back to an old branch if reviewing takes a while. There’s also less of an incentive to fix the build, because it doesn’t immediately effect you. It’s also more painful to change something that affects many, many files.
* “Trunk based development” – apparently Google do this. Everything is committed to trunk, all the time, there are no separate code reviews, and half-developed features are disabled via feature toggles. Large scale changes can be handled by putting the change behind an interface, and then switching code behind the interface.
We discussed these models. Several people expressed scepticism about trunk-based development – in their experience, committing directly to trunk has generally led to long pauses between commits, rather than shorter development ccycles. We use short-lived feature branches – and while we do sometimes have problems with huge changes, we don’t typically have a problem with people not dealing with broken builds (because our culture is that the build should be fixed quickly).
Testing in Production
In a talk about Testing in Production by Unruly, they described that their process has teams responsible for specific features from end-to-end. This encourages developers to make the code more robust, because the dev team are the people responsible for it in production and will be woken up by pagers if it goes wrong.
They test their code in production, because it is too much work to maintain an exact mirror of the live environment. They have no QA environments. Half-developed features are kept out of production via “feature toggles” and “data toggles”. They have lots of monitoring on their live servers – they monitor things that are of value to the company – like “are we making money” rather than “have the servers gone down”. “Monitoring driven development” is about first writing a monitor to check your new feature, and then developing the code for it – similar to test-driven development but much more so. They also use a chaos-monkey style approach for testing – with badly behaved client code, load testing with extreme events – because if someone is going to break the live environment, it might as well be them. They also use mob programming.
We discussed this – many of these approaches seem interesting and appropriate for a company that has very granular income, from a very large number of clients, that is coming in quickly and very responsively. They seem less relevant to more traditional companies.
Pia-Maria Thorens spoke about delegation poker. Chris showed a set of “delegation poker” cards, that showed the continuum of delegation decisions between “the manager makes the decision on his own” and “the team makes the decisions entirely without the manager”.
We discussed this as an interesting way of thinking about management and delegation.