WaitCondition Overview: Signal-Driven Stack Execution Control - ROS - Alibaba Cloud - Resource Orchestration Service

ALIYUN::ROS::WaitCondition waits for signals and works with ALIYUN::ROS::WaitConditionHandle to control the execution flow of a stack. For example, when you create an Elastic Compute Service (ECS) instance, a signal is sent during user data execution.

Syntax

{
  "Type": "ALIYUN::ROS::WaitCondition",
  "Properties": {
    "Count": Number,
    "Handle": String,
    "Timeout": Number,
    "ShowProgressEvent": String
  }
}

Properties

Property	Type	Required	Editable	Description	Constraint
Handle	String	Yes	No	The reference to an ALIYUN::ROS::WaitConditionHandle instance.	None.
Timeout	Number	Yes	No	The timeout period for receiving UserData messages.	Valid values: 1 to 43200. Unit: seconds.
Count	Number	No	Yes	The total number of UserData messages that Resource Orchestration Service (ROS) must receive.	None.
ShowProgressEvent	String	No	No	Specifies whether to display progress events for receiving UserData messages.	Valid values: Disabled (default): does not display progress events. Enabled: displays progress events. EnabledIfCreateStack (not recommended): displays progress events only during stack creation.

Return values

Fn::GetAtt

Data: the JSON string of the most recently created or updated signal data.
JoinedErrorData: a string of the ErrorData content.
ErrorData: the JSON string of the most recently created or updated error signal data.

Examples

YAML format

ROSTemplateFormatVersion: '2015-09-01'
Description: ''
Parameters: {}
Outputs: {}
Resources:
  InstallNginx:
    Type: 'ALIYUN::ECS::RunCommand'
    Properties:
      Type: RunShellScript
      CommandContent:
        'Fn::Replace':
          - ros-notify:
              'Fn::GetAtt':
                - InstallNginxWaitConditionHandle
                - CurlCli
          - |
            #!/bin/sh
            yum install -y nginx
            systemctl restart nginx
            if [[ $? -eq 0 ]];
            then
            ros-notify -d "{\"status\" : \"SUCCESS\"}"
            else
            ros-notify -d "{\"status\" : \"FAILURE\"}"
            fi
      Name: InstallNginxScript
      InstanceIds:
        - i-wz995r4yn8njthoq****
      Timeout: 60
  InstallNginxWaitConditionHandle:
    Type: 'ALIYUN::ROS::WaitConditionHandle'
  InstallNginxWaitCondition:
    Type: 'ALIYUN::ROS::WaitCondition'
    Properties:
      Handle:
        Ref: InstallNginxWaitConditionHandle
      Timeout: 60
Metadata: {}

JSON format

{
  "ROSTemplateFormatVersion": "2015-09-01",
  "Description": "",
  "Parameters": {},
  "Outputs": {},
  "Resources": {
    "InstallNginx": {
      "Type": "ALIYUN::ECS::RunCommand",
      "Properties": {
        "Type": "RunShellScript",
        "CommandContent": {
          "Fn::Replace": [
            {
              "ros-notify": {
                "Fn::GetAtt": [
                  "InstallNginxWaitConditionHandle",
                  "CurlCli"
                ]
              }
            },
            "#!/bin/sh\nyum install -y nginx\nsystemctl restart nginx\nif [[ $? -eq 0 ]];\nthen \nros-notify -d \"{\\\"status\\\" : \\\"SUCCESS\\\"}\" \nelse \nros-notify -d \"{\\\"status\\\" : \\\"FAILURE\\\"}\" \nfi \n"
          ]
        },
        "Name": "InstallNginxScript",
        "InstanceIds": [
          "i-wz995r4yn8njthoq****"
        ],
        "Timeout": 60
      }
    },
    "InstallNginxWaitConditionHandle": {
      "Type": "ALIYUN::ROS::WaitConditionHandle"
    },
    "InstallNginxWaitCondition": {
      "Type": "ALIYUN::ROS::WaitCondition",
      "Properties": {
        "Handle": {
          "Ref": "InstallNginxWaitConditionHandle"
        },
        "Timeout": 60
      }
    }
  },
  "Metadata": {}
}