Re-prompt for telemetry opt-in at each minor version upgrade, if not opted in

[bmcconaghy]

Many products do this, including things like IOS updates, so it will not be unusual to users. It’s worth noting that customer upgrades happen at most once every 2 months, and the message would only be shown once per upgrade, so should be very little fatigue. This will also fit in with the Guides concept.

[pmuellr]

starting to poke around, seems like it was mentioned on the call discussing the issue that the current behavior is to check every major release, but we want to check every minor release. Not seeing any specific major release check, but this may have something to do with there being things like a "v2" /api/telemetry/v2/optIn, perhaps that "v" gets updated every major.

Also on the call was a mention of working with older versions of ES (and maybe Kibana), but it also sounded like this was just going to be for 7.5, so ... not sure if there are "old versions of ES or Kibana" aspects relevant to this issue or not.

[pmuellr]

Looking at the .kibana* index, I can see an SO for telemetry:

{
    "telemetry": {
      "enabled": false
    },
    "type": "telemetry",
    "updated_at": "2019-10-28T21:39:48.219Z"
  }

So seems like we will need to extend this to include the version of Kibana in use when the SO is updated. Eg, kibana_version. Then the determination of whether to display with the banner would be:

(so == null) || (!so.telemetry.enabled && so.kibana_version < current kibana version)

Kinda thing.

We'll need to define how to compare Kibana versions - I'm guessing there's a semver-happy version of the kibana version, in which case we can use the semver package to do the comparison.

[pmuellr]

The relevant mappings for telemetry appear to be here:

kibana/src/legacy/core_plugins/telemetry/mappings.json

Lines 1 to 9 in b6591eb

	{
	"telemetry": {
	"properties": {
	"enabled": {
	"type": "boolean"
	}
	}
	}
	}

Seems fine to allow null values for previous versions of Kibana, couldn't be the latest version if it was null, right? (well hopefully). So, no migration required? Or is a migration required to even get the mappings updated? Guessing that might be the case.

[elasticmachine]

Pinging @elastic/kibana-stack-services (Team:Stack Services)