## Summary
Fixes flake tests of:
https://github.com/elastic/kibana/issues/115918https://github.com/elastic/kibana/issues/103273https://github.com/elastic/kibana/issues/108640https://github.com/elastic/kibana/issues/109447https://github.com/elastic/kibana/issues/100630https://github.com/elastic/kibana/issues/94535https://github.com/elastic/kibana/issues/104260
Security solution has been using `bsearch` and has encountered flake in various forms. Different developers have been fixing the flake in a few odd ways (myself included) which aren't 100%. This PR introduces a once-in-for-all REST API retry service called `bsearch` which will query `bsearch` and if `bsearch` is not completed because of async occurring due to slower CI runtimes it will continuously call into the `bsearch` with the correct API to ensure it gets a complete response before returning.
## Usage
Anyone can use this service like so:
```ts
const bsearch = getService('bsearch');
const response = await bsearch.send<MyType>({
supertest,
options: {
defaultIndex: ['large_volume_dns_data'],
}
strategy: 'securitySolutionSearchStrategy',
});
```
If you're using a custom auth then you can set that beforehand like so:
```ts
const bsearch = getService('bsearch');
const supertestWithoutAuth = getService('supertestWithoutAuth');
const supertest supertestWithoutAuth.auth(username, password);
const response = await bsearch.send<MyType>({
supertest,
options: {
defaultIndex: ['large_volume_dns_data'],
}
strategy: 'securitySolutionSearchStrategy',
});
```
## Misconceptions in the tests leading to flake
* Can you just call the bsearch REST API and it will always return data first time? Not always true, as when CI slows down or data increases `bsearch` will give you back an async reference and then your test will blow up.
* Can we wrap the REST API in `retry` to fix the flake? Not always but mostly true, as when CI slows down or data increases `bsearch` could return the async version continuously which could then fail your test. It's also tedious to tell everyone in code reviews to wrap everything in `retry` instead of just fixing it with a service as well as inform new people why we are constantly wrapping these tests in `retry`.
* Can we manually parse the `bsearch` if it has `async` for each test? This is true but is error prone and I did this for one test and it's ugly and I had issues as I have to wrap 2 things in `retry` and test several conditions. Also it's harder for people to read the tests rather than just reading there is a service call. Also people in code reviews missed where I had bugs with it. Also lots of boiler plate.
* Can we just increase the timeout with `wait_for_completion_timeout` and the tests will pass for sure then? Not true today but maybe true later, as this hasn't been added as plumbing yet. See this [open ticket](https://github.com/elastic/kibana/issues/107241). Even if it is and we increase the timeout to a very large number bsearch might return with an `async` or you might want to test the `async` path. Either way, if/when we add the ability we can increase it within 1 spot which is this service for everyone rather than going to each individual test to add it. If/when it's added if people don't use the bsearch service we can remove it later if we find this is deterministic enough and no one wants to test bsearch features with their strategies down the road.
## Manual test of bsearch service
If you want to manually watch the bsearch operate as if the CI system is running slow or to cause an `async` manually you manually modify this setting here:
https://github.com/elastic/kibana/blob/master/src/plugins/data/server/search/strategies/ese_search/request_utils.ts#L61
To be of a lower number such as `1ms` and then you will see it enter the `async` code within `bsearch` consistently
## Reference PRs
We cannot set the wait_for_complete just yet
https://github.com/elastic/kibana/issues/107241 so we decided this was the best way to reduce flake for testing for now.
### Checklist
- [x] [Unit or functional tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html) were updated or added to match the most common scenarios
ae7b5a9be9