Make a background job idempotent

acks_late replays a crashed job, but nobody has checked what a second run does to a real charge.

Beginner to intermediateRead 4 minDoing: an afternoon6 steps

What you'll have at the end

A job that reaches the gateway with the same result whether it runs once or five times, proven by redelivering it on purpose and reading the gateway's own ledger rather than trusting its replies

Before you start

You need

A background job that already runs behind a queue with confirm-after-success acknowledgment turned on, and that places a real charge with an outside payment gateway as part of its work.

Not covered

Any of the job's own database writes made in the same run carry their own protection, a separate concern from the gateway call this recipe closes.

Leans on

6 steps

Where to go next

Make your queue consumer idempotent

shows the database-ledger approach this recipe's gateway-side fix leans on instead, useful when the job also writes rows of its own or when the outside system has no idempotency-key convention to reuse.

Checked 19 Aug 2026

Part of the Background Job Processing Systems cookbook