I attended the always-excellent QCon developer conference in London earlier this week. James Governor from Redmonk what there, presenting what he calls Progressive Delivery, the idea being that rather than rolling out continuous and (mostly) small changes to everyone, you segment your deployments. Progressive deployment, see.

It is not really a new idea and might even be considered a rediscovery of what we already knew: that it makes sense to deploy new stuff to a small sample first. However it is true that tools are constantly evolving, and Progressive Delivery is perhaps best seen as a necessary refinement to the Continuous Delivery concept. In particular, LaunchDarkly exhibited at QCon; the product is a feature management platform which lets you create groups of users and toggle features on or off for particular groups. Needless to say, the LaunchDarkly folk love the Progressive Delivery concept.

Why Progressive Delivery? My first reaction is that this is about caution: if stuff breaks, let us make sure it only breaks for a few users. Then I saw that it can be equally about bold experimentation, trying new ideas with small groups so you can observe what works and what does not.

Of course you can do this anyway and in the end there is no magic in LaunchDarkly; it is still down to the developer to write the code:

This stuff can also easily become non-trivial; one attendee asked about managing database structure and it is obvious that not all features are equally amenable to being switched on or off for groups of users.

Still, I reckon “how do you manage features?” is a good question to add to the list when considering DevOps tools.

You can read most of what Governor talked about in his post from last year here.