Use Change Analysis in Azure Monitor

While standard monitoring solutions might alert you to a live site issue, outage, or component failure, they often don't explain the cause. For example, your site worked five minutes ago, and now it's broken. What changed in the last five minutes?

We've designed Change Analysis to answer that question in Azure Monitor.

Building on the power of Azure Resource Graph, Change Analysis:

  • Provides insights into your Azure application changes.
  • Increases observability.
  • Reduces mean time to repair (MTTR).

Note

Change Analysis is currently only available in Public Azure Cloud.

Change Analysis architecture

Change Analysis detects various types of changes, from the infrastructure layer through application deployment. Change Analysis is a subscription-level Azure resource provider that:

  • Checks resource changes in the subscription.
  • Provides data for various diagnostic tools to help users understand what changes might have caused issues.

The following diagram illustrates the architecture of Change Analysis:

Architecture diagram of how Change Analysis gets change data and provides it to client tools.

Supported resource types

Azure Monitor Change Analysis service supports resource property level changes in all Azure resource types, including common resources like:

  • Virtual Machine
  • Virtual machine scale set
  • App Service
  • Azure Kubernetes Service (AKS)
  • Azure Function
  • Networking resources:
    • Network Security Group
    • Virtual Network
    • Application Gateway, etc.
  • Data services:
    • Storage
    • SQL
    • Redis Cache
    • Azure Cosmos DB, etc.

Data sources

Azure Monitor's Change Analysis queries for:

Change Analysis also tracks resource dependency changes to diagnose and monitor an application end-to-end.

Azure Resource Manager resource properties changes

Using Azure Resource Graph, Change Analysis provides a historical record of how the Azure resources that host your application have changed over time. The following basic configuration settings are set using Azure Resource Manager and tracked by Azure Resource Graph:

  • Managed identities
  • Platform OS upgrade
  • Hostnames

Resource configuration changes

In addition to the settings set via Azure Resource Manager, you can set configuration settings using the CLI, Bicep, etc., such as:

  • IP Configuration rules
  • TLS settings
  • Extension versions

These setting changes are not captured by Azure Resource Graph. Change Analysis fills this gap by capturing snapshots of changes in those main configuration properties, like changes to the connection string, etc. Snapshots are taken of configuration changes and change details every up to 6 hours. See known limitations.

Changes in Azure App Services Function and Web Apps (in-guest changes)

Every 30 minutes, Change Analysis captures the configuration state of a web application. For example, it can detect changes in the application environment variables, configuration files, and WebJobs. The tool computes the differences and presents the changes.

Screenshot of the selecting the Refresh button to view latest changes.

If you don't see file changes within 30 minutes or configuration changes within 6 hours, refer to our troubleshooting guide.

See known limitations.

Currently, all text-based files under site root wwwroot with the following extensions are supported:

  • *.json
  • *.xml
  • *.ini
  • *.yml
  • *.config
  • *.properties
  • *.html
  • *.cshtml
  • *.js
  • requirements.txt
  • Gemfile
  • Gemfile.lock
  • config.gemspec

Dependency changes

Changes to resource dependencies can also cause issues in a resource. For example, if a web app calls into a Redis cache, the Redis cache SKU could affect the web app performance.

As another example, if port 22 was closed in a virtual machine's Network Security Group, it will cause connectivity errors.

Web App diagnose and solve problems navigator (preview)

To detect changes in dependencies, Change Analysis checks the web app's DNS record. In this way, it identifies changes in all app components that could cause issues.

Currently the following dependencies are supported in Web App Diagnose and solve problems | Navigator:

  • Web Apps
  • Azure Storage
  • Azure SQL

Limitations

  • OS environment: For Azure App Services Function and Web App in-guest changes, Change Analysis currently only works with Windows environments, not Linux.
  • Web app deployment changes: Code deployment change information might not be available immediately in the Change Analysis tool. To view the latest changes in Change Analysis, select Refresh.
  • App Services file changes: File changes take up to 30 minutes to display.
  • App Services configuration changes: Due to the snapshot approach to configuration changes, timestamps of configuration changes could take up to 6 hours to display from when the change actually happened.
  • Web app deployment and configuration changes: Since these changes are collected by a site extension and stored on disk space owned by your application, data collection and storage is subject to your application's behavior. Check to see if a misbehaving application is affecting the results.
  • Snapshot retention for all changes: The Change Analysis data for resources is tracked by Azure Resource Graphs (ARG). ARG keeps snapshot history of tracked resources only for 14 days.

Next steps