Collector builder functions are only used internally in the `collector`
package, and shouldn't needlessly be exposed as part of the package API
to downstream clients.
Signed-off-by: Ben Reedy <breed808@breed808.com>
Behaviour of init functions has been centralised in `collector/init.go`,
and can be called during exporter startup. This allows the exporter to
control the timing of collector initialisation, rather than relying on
the import & `init()` method.
This should reduce unexpected behaviour arising from the use of
`init()`, such as #551.
Signed-off-by: Ben Reedy <breed808@breed808.com>
This can be useful for building grafana dashboards with dropdowns for multiple hosts
Or for managed instances of Prometheus where the user is not able to add labels via config
If an WMI query were to return an empty result set, trying to access the
first element in the result set would result in a `panic: runtime error:
index out of range` error.
add logic to explicitly check if the result set size is 0 and return an
error rather.
Fixes https://github.com/martinlindhe/wmi_exporter/issues/240
