The intent is to use the instance struct to hold the connection to the database as well as metadata about the instance. Currently this metadata only includes the version of postgres for the instance which can be used in the collectors to decide what query to run. In the future this could hold more metadata but for now it keeps the Collector interface arguments to a reasonable number.
Signed-off-by: Joe Adams <github@joeadams.io>
Use const definitions to make collector registration consistent.
* Use collector subsystem name consistently.
* Fix up replication metric name unit.
Signed-off-by: SuperQ <superq@gmail.com>
