Observability: a practical guide

The advice here is unglamorous, which is probably why it gets skipped. This guide covers what observability 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.

What is actually at stake

Monitoring tells you something broke, observability tells you why. There is a version of this that is over-engineered, and it is worth avoiding. Doing this properly once is usually cheaper than doing it approximately three times.

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. None of that requires a large budget, only a decision and someone to own it.

What good looks like

Traces, metrics, and logs answer different questions. The reasoning matters more than the rule, because the rule has exceptions. The version that survives contact with a real deadline is the simple one.

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.

Instrument the paths that lose money first. Getting it slightly wrong is survivable. Ignoring it entirely is not. Most teams find the first pass takes an afternoon and the maintenance takes minutes a month.

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.

• Monitoring tells you something broke, observability tells you why
• Traces, metrics, and logs answer different questions
• Instrument the paths that lose money first
• 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

Where it usually goes wrong

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. The reasoning matters more than the rule, because the rule has exceptions.

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?

Making it stick

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.