Count API - count the number of documents in an index pattern

[Bargs]

Required by #6493

Description

This is a simple Kibana API that works similarly to Elasticsearch's _count api. The functionality is pared down and Kibana specific, only allowing you to retrieve the document count for a given index pattern.

Usage

The Count API supports both GET and POST requests for its single endpoint (POST was included so that the API can support a query body down the road, if required).

POST /api/kibana/{index_pattern}/_count
GET /api/kibana/{index_pattern}/_count

Response payload is a simple JSON document e.g.:

POST /api/kibana/logstash-*/_count

200 OK
{
  "count": 14005
}

Returns 404 if the pattern matches no existing indices.

[rashidkpc]

Let's support both GET and POST here.

[Bargs]

@rashidkpc so the same endpoint, just accessible by either method? Or I should say, the same functionality.

[Bargs]

@rashidkpc added support for GET. Ready for another look.

[rashidkpc]

Can this just be ['GET', 'POST']?

[Bargs]

Yes, I even looked that up yesterday, I guess I didn't have enough coffee this morning. Updated.

[rashidkpc]

LGTM