Adding an idempotency key to task context

[geomagilles]

Hi, while it may be possible for the user to build their own idempotency key (actually I'm not even sure it could be done reliably), I think it would be convenient to provide one out of the box.

It could be provided by runtime and accessible through e.g. $task.idempotencyKey

[matthias-pichler]

Do I understand correctly that this would be a per task idempotency token? Or per workflow?

I can see value in a per task idempotency token. For example when using a Stripe API in a task one could use the task idempotency token to make sure that retries don't end up charging a customer twice.

A per execution idempotency token (for making sure no duplicate executions are started) should probably be a runtime implementation concern, e.g. in the API.

[geomagilles]

Yes - the idea is to provide an idempotency key per task execution, so it would be different for each workflow instance, but same during retries.

As a task can legitimely be processed multiple time in the same workflow instance, we can not use the position for example - so yes I believe it should be provided by the runtime