Build namespace and ingress class as label

[gianrubio]

@aledbf I made a mistake when I built the nginx nomenclature. The right way to fill namespace and ingress class is using labels, so it'll easy to filter and reuse.

Old format

New format

Alarm example

    ALERT NginxTooMany5XX
      IF sum by (ingress_class, status_code, server_zone) (rate(nginx_responses_total{status_code=~"[5]xx"}[5m]) ) > ( 1.1 * sum by (ingress_class, status_code, server_zone) (rate(nginx_responses_total{status_code=~"[5]xx"}[15m]) ) )
      LABELS {
        service = "nginx",
        severity = "critical"
      }
      ANNOTATIONS {
        summary = "Too many http 5XX errors,
        description = " Status code {{ $status_code }} increased 10% in the last 5 minutes. Ingress class {{ $labels.ingress_class }} on server zone {{ $labels.server_zone }}",
      }

[k8s-reviewable]

This change is 

[aledbf]

please 1 line per attribute

[gianrubio]

Fixed

[aledbf]

please 1 attribute per line

[gianrubio]

Fixed

[coveralls]

Coverage increased (+0.01%) to 44.083% when pulling aa8a6de on gianrubio:review-prometheus into 22c3226 on kubernetes:master.

[aledbf]

/lgtm

[aledbf]

@gianrubio can you add an example showing how to set one or more alerts? (not in this PR)

[gianrubio]

@gianrubio can you add an example showing how to set one or more alerts? (not in this PR)

Sure, I'm working on this :)

[coveralls]

Coverage increased (+0.03%) to 44.1% when pulling 197acf0 on gianrubio:review-prometheus into 22c3226 on kubernetes:master.

[coveralls]

Coverage increased (+0.01%) to 44.083% when pulling 197acf0 on gianrubio:review-prometheus into 22c3226 on kubernetes:master.

[aledbf]

@gianrubio thanks!