CloudOps Orchestration Service:Conditions

The outermost function of each condition must be defined by Fn::And, Fn::Or, Fn::Not, or Fn::Equals. Each condition can reference other conditions, parameter values, or mappings. To associate a condition with a task, specify the When field in the Tasks section of a template.

Syntax

A condition declaration consists of a condition name and a condition statement. The condition name is of the STRING type and must be unique. The following functions can be used to define condition statements. A condition can reference other conditions.

• Fn::And

• Fn::Or

• Fn::Not

• Fn::Equals

You can use built-in functions within conditions, but the outermost function must be one of the preceding four functions.

Examples

• Reference template parameters

  You can reference parameters declared in the Parameters section of a template. The following example references the buildType parameter.

  Conditions:
    NewTemporaryEcs:
      Fn::Equals:
        - '{{ buildType }}'
        - NewTemporaryEcs

• Reference task output parameters

  You can reference the output parameters of a prerequisite task in a condition. The following example references the existed output parameter of the checkPolicyExist task.

  Conditions:
    createStack:
      Fn::Equals:
        - '{{ checkPolicyExist.existed }}'
        - 'false'
  Tasks:
    - Name: checkPolicyExist
      Action:  ACS::CheckFor
      Description:
        en: Check for the inexistence of policy
        zh-cn: the description in Chinese
      Properties:
        Service: RAM
        API: GetPolicy
        Parameters:
          PolicyType: 'Custom'
          PolicyName: '{{ policyName }}'
        DesiredValues:
        - 'true'
        - 'false'
        PropertySelector: '.DefaultPolicyVersion != null|tostring'
      Outputs:
        existed:
          Type: String
          ValueSelector: .DefaultPolicyVersion == null|tostring

  Note: If you reference dynamic parameters in a condition, the referenced task must be the prerequisite task of the task to which the condition is associated.

• Multi-level nested functions

  You can nest multiple levels of functions in conditions for complex evaluation logic.

  Conditions:
    downloadWindowsFile:
      Fn::And:
        - Fn::Equals:
            - '{{ queryInstanceOSType.OSType }}'
            - windows
        - Fn::Not:
            Fn::Equals:
              - '{{ artifactsUrl }}'
              - ''

Sample template

• The following template associates conditions with tasks to determine which task to execute based on the operating system.

  FormatVersion: OOS-2019-06-01
  Description:
    name-en: ACS::ECS::CleanUpDisk
    name-zh-cn: the description in Chinese
    en: Cleanup disk by run command
    zh-cn: the description in Chinese
  # Configure the conditions in the Conditions section.
  Conditions:
    Linux:
      Fn::Equals:
          - '{{ queryInstanceOSType.OSType }}'
          - linux
    Windows:
      Fn::Equals:
          - '{{ queryInstanceOSType.OSType }}'
          - windows
  Parameters:
    regionId:
      Description:
        en: The ID of region
        zh-cn: the description in Chinese
      Type: String
      Default: '{{ ACS::RegionId }}'
    instanceId:
      Description:
        en: The ID of ECS instance
        zh-cn: the description in Chinese
      Type: String
  Tasks:
    - Name: queryInstanceOSType
      Action: 'ACS::ExecuteApi'
      Description:
        en: Queries ECS instance OS type
        zh-cn: the description in Chinese
      Properties:
        Service: ECS
        API: DescribeInstances
        Parameters:
          RegionId: '{{ regionId }}'
          InstanceIds:
            - '{{ instanceId }}'
      Outputs:
        OSType:
          Type: String
          ValueSelector: 'Instances.Instance[].OSType'
    - Name: cleanupLinuxInstanceDisk
      # Check whether the operating system is Linux.
      When: Linux
      Action: 'ACS::ECS::RunCommand'
      Description:
        en: Runs cleanup disk command on linux instance
        zh-cn: the description in Chinese
      Properties:
        regionId: '{{ regionId }}'
        commandContent: |-
          #!/bin/bash
          cleanUpInfos="{{cleanUpInfos}}"
          # Run the command to clear data in the disk.
        instanceId: '{{ instanceId }}'
        commandType: RunShellScript
      Outputs:
        result:
          Type: String
          ValueSelector: .invocationOutput
    - Name: cleanupWindowsInstanceDisk
      # Check whether the operating system is Windows.
      When: Windows
      Action: 'ACS::ECS::RunCommand'
      Description:
        en: Runs cleanup disk command on windows instance
        zh-cn: the description in Chinese
      Properties:
        regionId: '{{ regionId }}'
        commandContent: |-
          #!/bin/bash
          cleanUpInfos="{{cleanUpInfos}}"
          # Run the command to clear data in the disk.
        instanceId: '{{ instanceId }}'
        commandType: RunPowerShellScript
      Outputs:
        result:
          Type: String
          ValueSelector: .invocationOutput
  Outputs:
    commandOutput:
      Type: String
      Value:
        'Fn::If':
          - 'Fn::Equals':
              - linux
              - '{{ queryInstanceOSType.OSType }}'
          - '{{ cleanupLinuxInstanceDisk.result }}'
          - '{{ cleanupWindowsInstanceDisk.result }}'