- type: replace
  path: /instance_groups/name=prometheus2/jobs/name=prometheus2/properties/prometheus/custom_rules?/-
  value:
    name: syslog-drains
    rules:
    - alert: CFSyslogDrainsWarning
      expr: firehose_value_metric_cf_syslog_drain_scheduler_drains > 250
      labels:
        deployment: ((metrics_environment))
        severity: warning
        runbook: "https://github.com/cloudfoundry/cf-syslog-drain-release/tree/v6.4#syslog-adapter"
      annotations:
        summary: Syslog drains
        description: "Consider scaling the adapters to cope with the number of syslog drains."

Add example alert rule for SyslogDrains capacity
Add example alert rule for SyslogDrains capacity

We add an example alert for the syslog drains capacity as defined
in terraform/datadog/syslog_drains.tf

It alerts when we reach more than 250

We split the runbook as a label, which can be later use in
templates, and remove the notification email.

Signed-off-by: Lee Porte <ddf032bb90eb8c33b2ad215511917a19dfc0c0c0@digital.cabinet-office.gov.uk>
