Azure Monitor is a service that delivers a comprehensive solution for collecting, analyzing, and acting on telemetry (metrics and logs) from your cloud and on-premises environments.

• Platform Logs

• By default the Activity Log keeps logs for 90 days.

• Metrics are numeric values collected at regular intervals (e.g. CPU utilization, disk IOPS, network connections, etc.)
  • Metrics are produced automatically without any configuration done by the user
• Logs are textual data that are produced organically as things occur in the environment (e.g. user login event)
  • Logs are not collected until things are collected until configuration is done by administrators
• Most Azure resources have an option to enable Diagnostic Logs
• Azure Monitoring Agent (AMA) is an agent that runs on Windows or Linux OS that can collect logs and metrics.
• Some logs are automatically generated by resources by default, but for more details logging it maybe necessary to enabled diagnostics logs for a resource, or, in the case of VMs, install an agent on the OS.
• Azure Monitor Log Analytics is a tool used to produce insights from Azure Monitor logs.

• Resource Logs were previously called Diagnostic Logs
• https://docs.microsoft.com/en-us/azure/azure-resource-manager/management/control-plane-and-data-plane

These logs differ from the activity log. The activity log (previously known as audit logs) provides insight into the operations, such as creating a VM or deleting a logic app, that Azure Resource Manager performed on resources in your subscription using. The activity log is a subscription-level log. Resource-level diagnostic logs provide insight into operations that were performed within that resource itself, such as getting a secret from a key vault.

• activity logs represent events on the control/management plane
  • The represent operations performed on resources
  • They represent the creation and modification of resources
  • Ex: creating a container in a storage account
• resource logs represent events on the data plane
• resource logs// were previously called diagnostic logs; they represent operations that were performed within a resource
  • They represent logs related to the use of resources.
  • Ex: Reading data from a blob/file in a container

• Resource logs are automatically generated by supported Azure resources, but they aren't available to be viewed unless you create a diagnostic setting.

• To install AMA on a machine it needs to be registered with a Log Analytics Workspace and this is done by specify the Workspace ID and Workspace key.

A Log Analytics workspace is a unique environment for log data from Azure Monitor and other Azure services, such as Microsoft Sentinel and Microsoft Defender for Cloud. Each workspace has its own data repository and configuration but might combine data from multiple services.

Log Analytics is a tool in the Azure portal to edit and run log queries from data collected by Azure Monitor logs and interactively analyze their results.