[APM] Use terms enum to fetch environments on Service inventory page

[sorenlouv]

We should use the terms_enum api to retrieve the environments on the Service inventory page. Currently we retrieve them via a term agg request:

kibana/x-pack/plugins/apm/server/routes/environments/get_environments.ts

Lines 38 to 71 in 8881539

	const operationName = serviceName
	? 'get_environments_for_service'
	: 'get_environments';
	const params = {
	apm: {
	events: [
	getProcessorEventForTransactions(searchAggregatedTransactions),
	ProcessorEvent.metric,
	ProcessorEvent.error,
	],
	},
	body: {
	track_total_hits: false,
	size: 0,
	query: {
	bool: {
	filter: [
	...rangeQuery(start, end),
	...termQuery(SERVICE_NAME, serviceName),
	],
	},
	},
	aggs: {
	environments: {
	terms: {
	field: SERVICE_ENVIRONMENT,
	missing: ENVIRONMENT_NOT_DEFINED.value,
	size,
	},
	},
	},
	},
	};

[elasticmachine]

Pinging @elastic/apm-ui (Team:APM)

[dgieselaar]

@sqren shouldn't this be about removing the unnecessary call to get_environments?

[sorenlouv]

@sqren shouldn't this be about removing the unnecessary call to get_environments?

If that's the problem, yes. I haven't determined if that's the case though.

[achyutjhunjhunwala]

@dgieselaar @sqren I have picked up this ticket to work on. Looking at the comments here, is the expectation different from what's in the description of the ticket ? Can you help me here detailing a bit more?

[sorenlouv]

@achyutjhunjhunwala The intention is to make sure that on the service inventory page we load environments using the terms enum api and only that. Dario suggests that maybe we are loading environments twice. It could be the case, in which case we should remove the duplicate call. If we only make one call and it doesn't use terms enum we should update the API.

[achyutjhunjhunwala]

@sqren Perfect, that's all the information i needed

[achyutjhunjhunwala]

@sqren I had a check at the network tab to see if we are calling the '/internal/apm/environments' twice, but i don't see that.

Regarding switching to term_enum api, i am not getting the exact result as we would get from the existing API. The term_enum api does not let to filter the result as we expect.

Let me know if you have something in mind around a custom filter which we can implement on the code side.

With current API

With Terms_Enum API

Even with index_filters we are getting different results

[sorenlouv]

Regarding switching to term_enum api, i am not getting the exact result as we would get from the existing API. The term_enum api does not let to filter the result as we expect.

Thanks for the thorough investigation @achyutjhunjhunwala ! We are not aiming for a 1:1 replacement so I think the terms enum query with index_filter is good enough.

I think in your case the result is a little exaggerated because of the nature of our data. I don't expect real users to see as big variances in service.environment terms over short periods of time.