feat(slo): Add support for custom index for APM indicator types

[kdelemme]

📝 Summary

Resolves #147280

This PR add an optional index parameter for both APM indicator types to allow custom integration to configure which source index to use.

🧪 Manual testing

Create SLO with specified index

curl --request POST \
  --url http://localhost:5601/kibana/api/observability/slos \
  --header 'Authorization: Basic ZWxhc3RpYzpjaGFuZ2VtZQ==' \
  --header 'Content-Type: application/json' \
  --header 'kbn-xsrf: oui' \
  --data '{
	"name": "My SLO Service Latency",
	"description": "My SLO Desc",
	"indicator": {
		"type": "sli.apm.transaction_duration",
		"params": {
			"environment": "development",
			"service": "o11y-app",
			"transaction_type": "request",
			"transaction_name": "GET /slow",
			"threshold.us": 5000000,
			"index": "custom-metrics-apm*"
		}
	},
	"time_window": {
		"duration": "7d",
		"is_rolling": true
	},
	"budgeting_method": "occurrences",
	"objective": {
		"target": 0.99
	}
}'

✅ Check the index is returned:

Fetch all SLO

curl --request GET \
  --url 'http://localhost:5601/kibana/api/observability/slos?per_page=10&page=1&=' \
  --header 'Authorization: Basic ZWxhc3RpYzpjaGFuZ2VtZQ==' \
  --header 'kbn-xsrf: oui'

✅ Check the transform > json in stack management is using the specified index

[kdelemme]

Pinging you @CoenWarmer since you discovered this while testing with CCS :)

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)

[maryam-saeidi]

Tested locally and worked as expected, just added some minor comments.

[maryam-saeidi]

nit: saving 'my-custom-apm-index*' in a const to use it in both places.

[maryam-saeidi]

Any reason to define DEFAULT_APM_INDEX twice? (also in apm_transaction_error_rate.ts)

[kdelemme]

No reason, I tend to prefer having the constants defined in the module instead of an external file, but not attached to that rule

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: a56bd12

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id	before	after	diff
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osquery	110	117	+7
securitySolution	521	527	+6
total			+21

History

• 💚 Build #93720 succeeded 8eb5eb1

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @kdelemme