Overview

Introduction

Metadata of an instance includes basic information of the instance in Alibaba Cloud, such as the instance ID, IP address, MAC addresses of network interface controllers (NICs) bound to the instance, and operating system type. Instance metadata also includes dynamic items generated after the instance is first started such as system events, instance identifiers, and user data.

For more information, see Retrieve instance metadata.

Metadata items

The following table lists basic metadata items that you can obtain from an ECS instance.

Dynamic metadata - O&M

For more information, see Overview.

Dynamic metadata - identity

Instance identifiers are used to identify and differentiate instances. This can provide trust foundation for application permission control and software activation. Instance identifiers consist of instance identity documents (document) and instance identity signatures (signature). For more information, see Instance identity.

Dynamic metadata - configuration

User data of an instance is implemented mainly based on different types of custom scripts and you can configure user data when you create the instance. User data allows users to customize instance startup and pass in data to the instance. For example, you can use user data to perform configuration operations such as automatically obtaining software resource packages, enabling services, printing logs, installing dependency packages, and initializing web environments. You can also pass in user data as common data to the instance and reference the data in the instance.

When the instance enters the Running state, the system runs the user data scripts by using the administrator or root permission. Then, the system runs the initialization information or the /etc/init folder.

For more information, see Prepare user data.