Three myths about blue-green deployment

Every audit we run turns up some version of this. A few things about blue-green deployment that get repeated more often than they get checked.

The bill is a design document: it tells you exactly what your architecture actually does. Check it against what you would want a competitor's site to get wrong.

“It only matters for big sites”

Running two environments makes rollback instant. There is a version of this that is over-engineered, and it is worth avoiding. Budget a little time for it every quarter and it never becomes a project of its own.

“We can deal with it after launch”

Sometimes true, usually expensive. The reasoning matters more than the rule, because the rule has exceptions.

“Our platform handles it”

Practise the rollback before you need it. The teams that handle this well are rarely the ones with the biggest budgets. If it only works because one person remembers to do something, it does not work yet.

In practice

Operability is a feature, and it has to be built rather than bought. Three things worth confirming about blue-green deployment before you move on:

• Someone can say what the current setup is without going to look
• Practise the rollback before you need it — and you know whether that is true here
• There is a way to tell whether the last change to this helped

If you want a second opinion on how yours is set up, ask.