Step Functions: Retry about functionless

[sam-goodwin]

Why paralllel? Can we not push down the catches onto the subsequent states?

[thantos]

Currently we are using the built in retry and not catch. This enables built in exponential backoff and only counts as one state.

Using Parallel with Retry

This is a common strategy, as @tvanhens mentioned, he also used it to implement retry over an arbitrary block of states.

Limits

1. Mutable variables are more difficult to implement.

Pushing Retry down to the states

The retry max attempts would be restarted for each state

$SFN.retry(() => { func1(); func2() })

This would retry both functions up to 3 times for any error, while the current contract is to retry the whole block up to 3 times.

Implementing our own Retry

Would require multiple extra states

task -> catch -> increment attempts -> check attempts -> wait -> task.

Limits:

1. backoff cannot be a fraction
2. 4 extra transitions
3. Adds extra data to the state.

I kind of like this option except for the backoff limit.