This commit introduces advanced configuration. The rate-interval and
label-prefix flags are removed, and replaced by a configuration file
that allows you to specify series queries and the rules for transforming
those into metrics queries and API resources.
This allows setting a prefix on the labels used to determine which
resources a series belongs to. The prefix may be set using the
`--label-prefix` flag.
This commit switches to using the boilerplate versions of
a couple different utilities, including the metric info normalization
and the common error types.
Previously, if we encountered an error while trying to update our series
list, we'd return an error, aborting the processing of the entire batch.
This could lead to the list of available metrics being severely out of
date. Instead, we simply log an error when we fail to process a metric
name, and skip it.
k8s.io/custom-metrics-boilerplate was "renamed" to
"github.com/directxman12/custom-metrics-boilerplate". This updates all
references to point to the correct location.
The initial functionality works. There's still a number of TODOs to
clean up, and some edge cases to work around, and some errors that could
be handled better.
