Resource Orchestration Service:How to specify different instance names and hostnames for batch-created ECS instances

When you use the ALIYUN::ECS::InstanceGroup resource type to batch-create ECS instances, you can give each instance a unique, predictable name and hostname without writing a separate template block per instance.

Set the InstanceName and HostName properties using the following pattern:

name_prefix[begin_number,bits]name_suffix

Naming pattern fields

• name_prefix — Required. The fixed prefix that appears at the start of every generated name.

• [begin_number,bits] — The auto-incrementing part. begin_number sets the starting number; bits sets how many digits the number occupies (zero-padded).

  The field must meet these requirements:

  • No spaces inside the brackets.

  • bits must be in the range of 1 to 4.

  • begin_number must be in the range of 0 to 9999.

  Default behavior for bits:

  • If you specify only begin_number (for example, [5]): bits defaults to 4, producing a 4-digit zero-padded number.

  • If you write [] or [,] (omitting both values): begin_number defaults to 0 and bits defaults to 4.

  • If begin_number has more digits than bits specifies (for example, [1234,1]): bits is overridden and defaults to 4, because begin_number (1234) already has four digits. This override applies only when begin_number is in the range of 0 to 9999.

• name_suffix — Optional. A fixed string appended after the incrementing number.

Batch instance naming example

The following template creates two ECS instances with distinct names and hostnames.

ROSTemplateFormatVersion: '2015-09-01'
Resources:
  WebServer:
    Type: ALIYUN::ECS::InstanceGroup
    Properties:
      ImageId: Cen****
      InstanceType: ecs.n4.large
      Password: Test1234
      MinAmount: 2
      MaxAmount: 2
      SecurityGroupId: sg-2zedcm7ep5quses0****
      SystemDiskCategory: cloud_efficiency
      IoOptimized: optimized
      InstanceName: my.test-[1114]
      HostName: host[]

ROS generates the following names:

• Instance names: my.test-1114 and my.test-1115 — InstanceName: my.test-[1114] means begin_number=1114, bits defaults to 4.

• Hostnames: host0000 and host0001 — HostName: host[] means begin_number defaults to 0, bits defaults to 4.