Azure Instance Metadata Service (IMDS) is a REST endpoint that provides a way for an Azure virtual machine (VM) to access its metadata from within the VM. This metadata includes information such as the VM’s hostname, network interfaces, location, and resource group. The IMDS is available on all Azure VMs and can be accessed through a non-routable IP address of 169.254.169.254.
IMDS is a lightweight service that runs on every Azure VM and provides a secure way for VMs to access their metadata. This metadata can be used by VMs to configure themselves, retrieve information about their environment, and interact with other Azure services. The metadata is available to all VMs regardless of the operating system or application running on them.
The IMDS endpoint is divided into two parts: the root level and the instance level. The root level provides information about the VM’s subscription, location, and resource group. The instance level provides information about the VM’s configuration, network interfaces, and extensions.
Key features and benefits of IMDS
- Secure Access: The IMDS is designed to provide secure access to metadata for Azure VMs. The metadata is only available from within the VM and cannot be accessed from outside the VM or over the network.
- Simplified Configuration: The IMDS provides a way for VMs to configure themselves using metadata. For example, a VM can retrieve its hostname, IP address, and network configuration from the IMDS during startup.
- Dynamic Scaling: The IMDS can be used to retrieve information about the VM’s environment and other Azure services. This information can be used to dynamically scale the VM’s resources based on the workload.
- Integration with Azure Services: The IMDS can be used to retrieve information about other Azure services that the VM is connected to. For example, a VM can retrieve its storage account name and key from the IMDS to access its storage account.
- Improved Troubleshooting: The IMDS provides a way to retrieve detailed information about the VM’s configuration and environment. This information can be used to troubleshoot issues and diagnose problems with the VM.
Overall, the Azure Instance Metadata Service is a powerful tool that provides VMs with access to critical metadata. It can be used to simplify VM configuration, dynamically scale resources, and improve troubleshooting. The IMDS is available on all Azure VMs and can be accessed through a secure, non-routable IP address.