Add support for vector tiles API

[iverase]

It would be great if we could add operations in rally that points to the vector tiles API. It currently fails because the result of the query is a protbuffer that the system does not understand.

[pquentin]

The main blocker for this issue is migrating to version 8.x of the Python client in #1350 as version 7.14 of the Elasticsearch Python client does not support that API. Support was added in 7.15.0: https://www.elastic.co/guide/en/elasticsearch/client/python-api/7.17/release-notes.html#rn-7-15-0. This API is quite specific in that it returns binary data, so it could make sense to wait for the upgrade, which hopefully should be done in March.

[pquentin]

@craigtaverner @iverase We released Rally 2.8.0 last month with the 8.x client. Are you still interested in doing that?

[iverase]

Yes we are super interested, need to find the time (and in my case, some python skills :))

[pquentin]

Can you maybe write how such an operation would look in a Rally track, so that we can see how difficult it would be to implement? Some runners are only a few lines of code.

[iverase]

A mvt request is very similar to a search request except it requires 4 mandatory parameters. One is the field where the geo data is, and the other three is the actual tile to be processed by providing the z/x/y values.

Therefore a simple example would look like:

 {
      "name": "mvt-search",
      "operation-type": "mvt",
       "z" : 11,
       "x" : 23,
       "y" : 145,
       "field": "my-geo-field",
      "body": {
           -- extra configuration here 
      }
    }

[iverase]

An example of how this would look like in the geoshape track is:

{
      "name": "mvt-search-hits",
      "operation-type": "mvt",
      "index": "osm*",
       "field": "shape",
       "z" : 2,
       "x" : 2,
       "y" : 1,
       "field": "my-geo-field",
      "body": {
           "grid_precision" : 0,
           "sort": [
               {
                 "size": {
                  "order": "desc"
                }
              }
           ]
      }
    }

or another example:

{
      "name": "mvt-search-grid",
      "operation-type": "mvt",
      "index": "osm*",
       "field": "shape",
       "z" : 2,
       "x" : 2,
       "y" : 1,
      "body": {
           "size" : 0,
            "grid_agg" : "geo_hex"
      }
    }