Monitor Azure Compute Scale Sets

Overview of Monitoring

Monitoring your Azure Compute Scale Sets (VMSS) is crucial for ensuring their availability, performance, and cost-effectiveness. Azure provides a rich set of tools and services to help you gain insights into your VMSS operations.

Key aspects to monitor include:

• Instance health and status
• Resource utilization (CPU, Memory, Disk, Network)
• Application performance
• Scaling events
• Cost and billing

Azure Monitor for VMSS

Azure Monitor is the central service for collecting, analyzing, and acting on telemetry from your Azure and on-premises environments. It provides comprehensive monitoring capabilities for VMSS.

Key Azure Monitor Features:

• Metrics: Collects numerical data about the performance of your VMSS instances. These can be visualized on dashboards and used to trigger alerts.
• Logs: Collects logs from your VMSS instances, including operating system logs, application logs, and custom logs. Log Analytics provides a powerful query language (KQL) for analysis.
• Alerts: Configurable rules that can notify you when specific conditions are met based on metrics or log data.
• Dashboards: Customizable views that bring together key metrics and logs for a consolidated overview.
• Application Insights: For deeper application performance monitoring, including request rates, response times, and failure rates.

Scenarios:

You can use Azure Monitor to:

• Track the number of running instances and identify unhealthy instances.
• Monitor average CPU usage across the scale set.
• Detect high network traffic or disk I/O.
• Identify applications that are consuming excessive resources.
• Set up alerts for automatic scaling or to notify operators of issues.

Instance Health

Understanding the health of individual virtual machines within your scale set is vital. Azure Monitor provides several ways to check instance health:

• VMSS Instance View: The Azure portal provides an "Instance view" for your scale set, showing the status of each individual VM instance (Running, Stopped, Failed, etc.).
• Azure Monitor Agent (AMA) / Log Analytics Agent: Deploying agents on your VMSS instances allows you to collect detailed health data and send it to Log Analytics for advanced querying and analysis.
• Health Probes (Load Balancer): If your VMSS is behind an Azure Load Balancer, configuring health probes ensures that traffic is only sent to healthy instances.

Performance Metrics

Monitor key performance indicators (KPIs) to ensure your applications are running efficiently and meeting performance targets.

Commonly monitored metrics include:

• CPU Percentage: Average CPU utilization across instances.
• Memory Percentage: Average memory utilization.
• Disk Read/Write Bytes/sec: Data transfer rates for disks.
• Network In/Out Total: Network traffic volume.
• Http Server Errors: For web applications hosted on VMSS.

You can view these metrics in the Azure portal under the "Monitoring" section of your VMSS resource, or by querying them in Log Analytics.

Perf
| where ObjectName == "Processor" and CounterName == "% Processor Time" and InstanceName == "_Total"
| summarize avg(CounterValue) by bin(TimeGenerated, 5m)
| render timechart
            

Logging and Diagnostics

Detailed logging is essential for troubleshooting and understanding application behavior.

• Azure Diagnostics Extension: A legacy but still functional extension for collecting OS and application logs, performance counters, and crash dumps.
• Azure Monitor Agent (AMA): The modern replacement for the Diagnostics Extension and Log Analytics Agent. It offers more flexibility and can collect data from multiple sources.
• Log Analytics Workspace: Centralize all your logs and metrics here for powerful analysis.

You can collect:

• Windows Event Logs (Application, System, Security)
• Linux Syslog
• IIS Logs
• Custom Application Logs

Alerting for Proactive Response

Set up alerts to be notified of potential issues before they impact your users.

Consider creating alerts for:

• High CPU or memory utilization
• Low disk space
• Application errors (e.g., HTTP 5xx errors)
• Unhealthy instance counts
• Scaling events

Alerts can trigger actions such as sending an email, triggering a webhook, or running an Azure Automation runbook.