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    Alerts

    Create a rule that fires when a host crosses a threshold, targeted at a group, an environment, or the whole fleet.

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    An alert rule watches one metric against a threshold. When a host crosses it, an alert opens against that host; when the host comes back under, the alert resolves.

    Before you begin#

    You need the Operator role or above, and at least one registered server whose connection check succeeds. Metrics come from that check, so a host that cannot be reached produces no readings to compare.

    1. Create the rule#

    Open Alerts and add a rule. It takes a metric, a comparison, and a threshold:

    Name        Production disks filling
Metric      disk_percent
Operator    greater than
Threshold   85

    Available metrics are the ones collected on every connection check:

    MetricWhat it is
    cpu_percentCPU in use
    mem_percentMemory in use
    disk_percentRoot filesystem in use
    load_avg_1, load_avg_5Load average over one and five minutes
    server_status1 when the host answered, 0 when it did not

    Comparisons are greater than, greater or equal, less than, less or equal, equal and not equal. server_status equal to 0 is how you alert on a host going offline.

    2. Target it#

    Two optional axes, combined with and:

    Group          web
Environment    production

    Leaving both empty matches every host. Setting one narrows to that group or that environment. Setting both means production web hosts only.

    3. Leave it enabled#

    A rule can be disabled without being deleted, which is what you want during planned maintenance rather than deleting a rule you will want back.

    Verify it worked#

    Set a threshold you know a host already crosses, such as disk_percent greater than 1, then run a connection check on that server. The alert appears against it:

    alerts
    Production disks filling    web-01    disk_percent 34 > 1    active

    Then raise the threshold back above the current value and check again. The alert resolves on its own rather than needing to be dismissed:

    alerts
    Production disks filling    web-01    resolved

    That round trip proves both directions: rules fire on the reading, and they clear when the reading changes.

    When rules are evaluated#

    On a connection check, not on a timer. Opafra is agentless, so nothing on the host pushes readings and nothing polls continuously. Metrics are read when a server is tested, which happens when you register it, when you test it by hand, and when a run touches it.

    Alerts are scoped to your tenant: a rule only ever evaluates against servers you own.

    Next steps#