add customfields to prometheus labels

[LivingInSyn]

Signed-off-by: Jeremy Mill [email protected]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area config

/area outputs

/area tests

What this PR does / why we need it:

This PR allows users to configure custom prometheus labels. It is separate from the CUSTOMFIELDS configuration to avoid creating too many series in prometheus.

Which issue(s) this PR fixes:
n/a

Fixes #

Special notes for your reviewer:
The primary use case is to do something like add a cluster and environment tag to prometheus metrics to differentiate between clusters and prod/dev environments.

Sample output from a test in my cluster with this build is:

falco_events{app_kubernetes_io_instance="falco", app_kubernetes_io_name="falcosidekick", cluster="security", environment="dev", instance="10.96.2.18:2801", job="kubernetes-pods", k8s_ns_name="default", k8s_pod_name="prom-prometheus-node-exporter-7zk92", namespace="default", pod="falco-falcosidekick-6fc876bb4c-njk9n", pod_template_hash="6fc876bb4c", priority="Informational", rule="Launch Sensitive Mount Container"}

I'm open to changing how this was done if there are concerns that I'm not aware of

[LivingInSyn]

@Issif I made sure the labels are valid prometheus labels according to their docs here in this commit: dd989ed

I wanted to also add unit testing to this since it seems a likely place to have an accidental breakage in the future. To support unit testing in the main package I added a check in 8761d46 to avoid running init when unit testing. This is because kingpin really doesn't work nicely with go test (see: alecthomas/kingpin#194 and other associated issues)

Let me know what you think

[poiana]

LGTM label has been added.

Git tree hash: fd34b4581def8af037c85d5fea7d5329e10e952d

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Issif, LivingInSyn

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