Respond to events with Azure Monitor Alerts

Log search rules are created by Azure Alerts to automatically run specified log queries at regular intervals. If the results of the log query match particular criteria, then an alert record is created. The rule can then automatically run one or more actions using Action Groups. This tutorial is a continuation of the Create and share dashboards of Log Analytics data tutorial.

In this tutorial, you learn how to:

  • Create an alert rule
  • Configure an Action Group to send an e-mail notification

To complete the example in this tutorial, you must have an existing virtual machine connected to the Log Analytics workspace.

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Create alerts

Alerts are created by alert rules in Azure Monitor and can automatically run saved queries or custom log searches at regular intervals. You can create alerts based on specific performance metrics or when certain events are created, absence of an event, or a number of events are created within a particular time window. For example, alerts can be used to notify you when average CPU usage exceeds a certain threshold, when a missing update is detected, or when an event is generated upon detecting that a specific Windows service or Linux daemon is not running. If the results of the log search match particular criteria, then an alert is created. The rule can then automatically run one or more actions, such as notify you of the alert or invoke another process.

In the following example, you create a metric measurement alert rule based off of the Azure VMs - Processor Utilization query saved in the Visualize data tutorial. An alert is created for each virtual machine that exceeds a threshold of 90%.

  1. In the Azure portal, click All services. In the list of resources, type Monitor. As you begin typing, the list filters based on your input. Select Monitor.
  2. In the left-hand pane, select Alerts and then click New Alert Rule from the top of the page to create a new alert.

    Create new alert rule

  3. For the first step, under the Create Alert section, you are going to select your Log Analytics workspace as the resource, since this is a log based alert signal. Filter the results by choosing the specific Subscription from the drop-down list if you have more than one, which contains the VM and Log Analytics workspace created earlier. Filter the Resource Type by selecting Log Analytics from the drop-down list. Finally, select the Resource DefaultLAWorkspace and then click Done.

    Create alert step 1 task

  4. Under the section Alert Criteria, click Add Criteria to define the query and then specify logic that the alert rule follows. From the Configure signal logic pane, select Custom log search as signal name and enter your query in Search query.

    For example:

    | where CounterName == "% Processor Time" and ObjectName == "Processor" and InstanceName == "_Total"
    | summarize AggregatedValue=avg(CounterValue) by bin(TimeGenerated, 1m)

    The pane updates to present the configuration settings for the alert. On the top, it shows the results for the last 30 minutes of the selected signal.

  5. Configure the alert with the following information:
    a. From the Based on* drop-down list select **Metric measurement. A metric measurement will create an alert for each object in the query with a value that exceeds our specified threshold.
    b. For the Condition, select Greater than and enter 90 for Threshold.
    c. Under Trigger Alert Based On section, select Consecutive breaches and from the drop-down list select Greater than enter a value of 3.
    d. Under Evaluation based on section, accept the defaults. The rule will run every five minutes and return records that were created within this range of the current time.

  6. Click Done to complete the alert rule.

    Configure alert signal

  7. Now moving onto the second step, provide a name of your alert in the Alert rule name field, such as Percentage CPU greater than 90 percent. Specify a Description detailing specifics for the alert, and select Critical(Sev 0) for the Severity value from the options provided.

    Configure alert details

  8. To immediately activate the alert rule on creation, accept the default value for Enable rule upon creation.

  9. For the third and final step, you specify an Action Group, which ensures that the same actions are taken each time an alert is triggered and can be used for each rule you define. Configure a new action group with the following information:
    a. Select New action group and the Add action group pane appears.
    b. For Action group name, specify a name such as IT Operations - Notify and a Short name such as itops-n.
    c. Verify the default values for Subscription and Resource group are correct. If not, select the correct one from the drop-down list.
    d. Under the Actions section, specify a name for the action, such as Send Email and under Action Type select Email/SMS/Push/Voice from the drop-down list. The Email/SMS/Push/Voice properties pane will open to the right in order to provide additional information.
    e. On the Email/SMS/Push/Voice pane, enable Email and provide a valid email SMTP address to deliver the message to.
    f. Click OK to save your changes.
    Create new action group

  10. Click OK to complete the action group.

  11. Click Create alert rule to complete the alert rule. It starts running immediately.

    Complete creating new alert rule

View your alerts in Azure portal

Now that you have created an alert, you can view Azure alerts in a single pane and manage all alert rules across your Azure subscriptions. It lists all the alert rules (enabled or disabled) and can be sorted based on target resources, resource groups, rule name, or status. Included is an aggregated summary of all the fired alerts, and total configured/enabled alert rules.

Azure Alerts status page

When the alert triggers, the table reflects the condition and how many times it occurred within the time range selected (the default is last six hours). There should be a corresponding email in your inbox similar to the following example showing the offending virtual machine and the top results that matched the search query in this case.

Alert email action example

Next steps

In this tutorial, you learned how alert rules can proactively identify and respond to an issue when they run log searches at scheduled intervals and match a particular criteria.

Follow this link to see pre-built Log Analytics script samples.