Tags are used to identify cloud resources. The tags allow you to categorize, search for, and aggregate cloud resources that have the same characteristics from different dimensions. This facilitates resource management.

Scenarios

Tags can be used to categorize and manage cloud resources. This improves search efficiency and allows you to perform operations on multiple cloud resources at a time.

  • Itemized billing

    In team or project management, you can bind tags such as CostCenter:aliyun to groups, projects, or departments. Then, you can categorize the objects and implement itemized billing or cross authorization based on the tags.

    Example 1 of tag use scenarios
  • Automatic O&M

    You can bind different tags to environments such as production and test environments, operating systems such as Windows and Linux, and mobile platforms such as iOS and Android. For example, create a tag named Test:Server-Windows and bind the tag to all Windows ECS instances in the test environment. You can easily filter these instances based on the Test:Server-Windows tag and perform operations on them.

    Example 2 of tag use scenarios

    You can perform the following operations on multiple instances at a time:

    • Change the image for application deployment.
    • Update patches.
    • Add security group rules to control access.
    • Use Operation Orchestration Service (OOS) to start, stop, or restart ECS instances.
    • Use Cloud Assistant to run the O&M script on multiple ECS instances.

Benefits

Tags provide the following benefits:
  • Convenience: A unified, visualized console is provided to manage all resources that are bound with tags.
  • Flexibility: You can bind, unbind, modify, or query one or more tags in the console or by calling an API operation.
  • Visibility: You can use tags to manage separate bills for departments, products, and projects.

Terms

Term Description
key-value pair

A tag consists of a key-value pair. Limits:

  • A tag key can contain a maximum of 128 characters and cannot contain http:// or https://. It cannot start with acs: or aliyun.
  • A tag value can contain a maximum of 128 characters and cannot contain http:// or https://. It cannot start with acs: or aliyun.
  • Each tag key of a resource can have only one tag value. If you create a tag that has the same key as an existing tag, the value of the existing tag is overwritten.

    For example, the city:shanghai tag is bound to a resource. If you bind the city:newyork tag to the resource, the city:shanghai tag is automatically unbound from the resource.

custom tag A custom tag is created by a user. For more information, see Create and bind a tag.
system tag A system tag is defined by the system. You can only query system tags.

Cloud services that support tags

A series of core Alibaba Cloud infrastructures support tags, such as Elastic Compute Service, ApsaraDB for RDS, Object Storage Service, Virtual Private Cloud, Server Load Balancer, and Alibaba Cloud Container Service for Kubernetes. Alibaba Cloud intends to add tag support for other cloud services. For more information, see Alibaba Cloud services that support tags.

Limits

  • A maximum of 20 tags can be bound to each cloud resource.
  • Tag information is not shared across regions. For example, in the China (Shanghai) region, you cannot view tags created in the China (Hangzhou) region.

Best practices

The best practices of tags are derived from the rich experience of the Alibaba Cloud service team in serving hundreds of customers. The following best practices help you understand how to better manage tags in your enterprise or organization: