Serverless: a practical guide

It is rarely the thing that gets a project approved, and often the thing that decides how it goes. This guide covers what serverless actually involves, where it usually goes wrong, and how to tell whether yours is in reasonable shape.

Cloud work rewards teams who automate early and punishes teams who click through consoles. Nothing below assumes a large team or a large budget — most of it is a decision somebody has to make and then write down.

The reason this keeps coming up

Excellent for spiky, event-shaped workloads. None of that requires a large budget, only a decision and someone to own it. If two people in the business would answer this differently, that gap is the actual problem.

For most businesses the question is not whether this matters but how much of it is worth doing right now. That depends on what you are trying to achieve in the next few months, not on best practice in the abstract. Getting it slightly wrong is survivable. Ignoring it entirely is not.

How to approach it

Cold starts and vendor coupling are the real trade-offs. Small and consistent beats large and occasional here. It is worth deciding this deliberately rather than inheriting whatever the last person set up.

The bill is a design document: it tells you exactly what your architecture actually does. The version that works in practice is usually less elaborate than the version described in the guides.

Cost modelling matters more here than anywhere else. The teams that handle this well are rarely the ones with the biggest budgets. It is the sort of thing that looks like polish right up until it costs you an enquiry.

A working checklist

If you want a quick read on where you stand, work through this. Anything you cannot answer confidently is where to start.

• Excellent for spiky, event-shaped workloads
• Cold starts and vendor coupling are the real trade-offs
• Cost modelling matters more here than anywhere else
• Someone is named as the owner, not just assumed to be
• There is a date in the calendar to review it again
• The decision and the reasoning behind it are written down somewhere findable
• You could explain the current setup to a new hire in five minutes

What to watch for

The most common failure is not doing this badly. It is doing it once, during a launch, and never revisiting it. Circumstances move, the setup does not, and the gap widens quietly until something breaks or somebody notices the numbers.

• It was configured during a launch and has not been touched since
• Different people in the business believe different things are true about it
• There is no way to tell whether the last change helped or hurt
• The only person who understands it has left, or is about to

Operability is a feature, and it has to be built rather than bought. Getting it slightly wrong is survivable. Ignoring it entirely is not.

How we approach it

On our projects this gets handled during the build rather than added afterwards, because retrofitting it costs several times more than including it. We write down what was decided and why, so the next person to touch it is not guessing.

If you are working with someone else, the questions worth asking are simple: who owns this, how will we know it is working, and what happens when it needs to change?

A reasonable first step

Pick the single item from the checklist above that would cause the most trouble if it turned out to be wrong. Fix that one, confirm it worked, then move on. Pick the one that would hurt most if it failed, and start there.