Metric Alerts
What it is
A metric alert is an Azure Monitor alert rule that watches a metric (a numeric signal) and fires when a condition is met — e.g. “CPU % > 90% for 10 consecutive minutes.” When triggered it activates an action group (email, SMS, webhook) and enters a fired state.
Why it exists
You can’t watch dashboards 24/7. Alerts automatically detect that a numeric signal crossed a threshold and notify/automate a response, giving sub-minute reaction times where metrics are available.
Key ideas
- Components: resource(s) to monitor + signal (metric) + condition & threshold + frequency of evaluation + action group + severity.
- Dynamic thresholds (algorithmic) can adapt to baseline instead of fixed numbers.
- States: fired / resolved; configured in Monitor → Alerts → Create alert rule.
- Alert processing rules can suppress/deselect notifications (e.g. during maintenance).
- Metric alerts give the fastest, lowest-cost detection vs log alerts.
How it fits (diagram)
Diagrams courtesy of Microsoft Learn / Azure docs: azure-monitor/alerts/alerts-overview
Exam notes
- Know the four alert signals in Azure Monitor: metric, log (KQL), activity log, resource/availability.
- Threshold + frequency + condition are the configurable core; action group is the notification target.
- Severity (0-4) and alert state (new/acknowledged/closed in Alert Management) are distinct concepts.
- For VMs, host CPU metric alerts work out-of-the-box; guest metrics need the agent.
Related
azure-monitor-metrics · action-group · log-analytics · azure-monitor-activity-log · Home
📘 Source: Microsoft Learn — Metric Alert