AssociationProperty and AssociationPropertyMetadata

Parameters

You can specify one of the following types of values for AssociationPropertyMetadata in ROS templates based on your business requirements:

• A literal value. For example, if you set AssociationPropertyMetadata to "RegionId": "cn-hangzhou", ROS resolves this value as the literal value cn-hangzhou.
• A variable. Specify a variable in the ${ParemeterKey} format. For example, if you set AssociationPropertyMetadata to "VpcId": "${VpcId}", ROS resolves this value as a variable that varies based on the value of the VpcId parameter in the template.
  Note

  • If you need to specify a variable in the ${ParemeterKey} format as a literal value, you can add an exclamation point (!) to ${ParemeterKey} to use the ${!ParemeterKey} format. For example, if you set a value to ${!Literal}, ROS resolves this value as ${Literal}.
  • If you need to specify a variable for a parameter in a Terraform template, add $ to ${ParemeterKey} to use the $${ParemeterKey} format. For example, if you set AssociationPropertyMetadata to "VpcId": "$${VpcId}", ROS resolves this value as a variable that varies based on the value of the VpcId parameter in the Terraform template.

The following table describes the relationship between the values of AssociationProperty and AssociationPropertyMetadata.

Example 1: AssociationProperty

In this example, AssociationProperty is set to ALIYUN::ECS::Instance::ImageId to query the IDs of all images in the selected region.

"Parameters": {
  "UserName": {
    "Label": "Username",
    "Description": "Enter the username",
    "Default": "anonymous",
    "Type": "String",
    "MinLength": "6",
    "MaxLength": "12",
    "AllowedValues": [
      "anonymous",
      "user-one",
      "user-two"
    ]
  },
  "PassWord": {
    "Label": "Password",
    "NoEcho": "True",
    "Description": "Enter the password",
    "Type": "String",
    "MinLength": "1",
    "MaxLength": "41",
    "AllowedPattern": "[a-zA-Z0-9]*"
  },
  "ImageId": {
    "Label": "Image",
    "Type": "String",
    "Description": "Select an image",
    "AssociationProperty": "ALIYUN::ECS::Instance::ImageId",
    "Default": "centos_7_7_x64_20G_alibase_2020****.vhd"
  }
}

Fields in the Parameters section:

• UserName: the username. The value is of the String type and must be 6 to 12 characters in length. Default value: anonymous. Valid values:
  • anonymous
  • user-one
  • user-two
• PassWord: the password. The value is of the String type. No default value is provided. The value must be 1 to 41 characters in length, and can contain letters and digits.

  NoEcho is set to true, which specifies that ROS returns a password that is set to ciphertext after you query the stack.

• ImageId: the ID of the image. The value is of the String type.

  AssociationProperty is set to ALIYUN::ECS::Instance::ImageId. This way, the ROS console verifies whether the ID of the specified image that you use to create the stack is valid. The ROS console also displays IDs of other images that are available in the same region as the specified image in a drop-down list.

Example 2: AssociationPropertyMetadata

In this example, AssociationProperty and AssociationPropertyMetadata are specified to query the vSwitch of the specified VPC and zone. For AssociationPropertyMetadata, RegionId is set to the literal value cn-hangzhou, VpcId is set to the variable ${VpcId}, and ZoneId is set to the variable ${EcsZone}. ${VpcId} varies based on the value of ALIYUN::ECS::VPC::VPCId, and ${EcsZone} varies based on the value of ALIYUN::ECS::Instance::ZoneId. This way, the vSwitch is associated with the specified VPC and zone.

{
  "ROSTemplateFormatVersion": "2015-09-01",
  "Parameters": {
    "VpcId": {
      "Type": "String",
      "AssociationProperty": "ALIYUN::ECS::VPC::VPCId"
    },
    "EcsZone": {
      "Type": "String",
      "AssociationProperty": "ALIYUN::ECS::Instance::ZoneId"
    },
    "VSwitchId": {
      "Type": "String",
      "AssociationProperty": "ALIYUN::ECS::VSwitch::VSwitchId",
      "AssociationPropertyMetadata": {
           "RegionId": "cn-hangzhou",
           "VpcId": "${VpcId}",
           "ZoneId": "${EcsZone}"
      }
    }
  }
}

More examples

You can specify AssociationProperty and AssociationPropertyMetadata to perform the following operations:

• Use mappings to automate the configuration of YUM repositories for CentOS systems
• Select parameter configurations in the ROS console
• Display different parameter sets based on the value of a parameter