Comparison
IdempotentvsIdempotent provisioning
Idempotent
you can safely run the same operation five times and the system ends up in exactly the state it would after one.
The property that applying an operation repeatedly has the same effect as applying it once. It is what makes retries safe, and retries are unavoidable in any networked system, because a timeout does not tell you whether the work happened. Idempotence is about the effect on state, not about the return value or the work performed.
Full entry →Idempotent provisioning
you ran the whole thing again after a network error and it created nothing new, because everything it wanted already existed.
The property that applying a configuration repeatedly converges on the same result rather than accumulating duplicates or errors. It is what makes automation safe to retry, and it is the practical reason declarative tooling won over scripts. It is also easy to break by hand, with a provisioner step that appends to a file or generates a random name on every run.
Full entry →