7.x Compatible Prometheus Exporter for 6.x clusters

Creating this for the discussion about creating a 7.x compatible prometheus exporter for 6.x.

7.x is the ongoing standard for metrics tracking in Couchbase Server. None of the current (5?) prometheus exporters adhere to this standard. This means that customers already making use of these exporters - or looking for monitoring solutions on their 6.x clusters will end up in a monitoring cul-de-sac whereby their dashboards and alerts are incompatible with version 7. This will consequently impede 7.x adoption.

This ticket proposes an alternative approach to CMOS-44, whereby we create a new version of the exporter (either scorched earth or reusing what we can from CNPE) to provide an exporter that works against 6.x clusters that delivers stats in a 7.x compatible fashion. This allows the creation of dashboards and monitoring rules that are agnostic to the version of Couchbase being run. i.e. upgrade Couchbase without having to upgrade your monitoring infrastructure.

To minimise effort, this new exporter would not need to support ALL 6.x metrics on day one. It could prioritise a core subset that were used in the core set of couchbase dashboards.

Questions that arise about the creation of this new/updated exporter include:

• How much effort would it be to create? (Justin estimates 20 days + QE time)
• How might it be packaged and distributed?
• Would it be officially supported and maintained or sold as seen?