Watchers: configurable iteration cap

[CameronNemo]

The foreach functionality added in #41997 contains a constant cap of 100 on iterations. This makes it inconvenient to use with bucket aggregations, which offer a configurable cap, defaulting to 10,000 buckets. I propose a configuration directive actions.<id>.max_iterations that replaces the hardcoded 100 cap.

[elasticmachine]

Pinging @elastic/es-core-features

[jakelandis]

@CameronNemo - I am curious to which action (and why) you want execute 10,000 actions for each watch ?

[CameronNemo]

index or webhook action. we have over 400 devices so the 100 limit simply does not cut it.

[CameronNemo]

1000 would probably be alright, but why was the limit placed at exactly 100 in the first place? was there a measurement of time took?

[jakelandis]

@CameronNemo - thanks for the feedback. 100 was an arbitrary upper bound to prevent an accidental mis-configuration and flooding some poor downstream system.

+1 to add a dynamic configuration option for this, with 100 as the default.

[jbonn360]

Hi guys, I'd like to work on this if that's ok.

[jakelandis]

@jbonn360 - all yours. Please target master and feel free to ping me for review. Also, I can handle the any back porting to next minor version(s).

[jbonn360]

@jakelandis Cheers, will do

[deXetrous]

Hi guys, I want to work on this if that's fine. Can you please help me to get started and understand the code base?

[jakelandis]

@deXetrous - thanks for the offer, but @jbonn360 has already submitted a PR for this.