AWS CloudFormation conditional tagging

Question

I have a requirement to conditionally tag resources based on user response to the downtime parameter and the value of environment defined in map. This tag is later used by the lambda function to turn off the instances at night.

I tried it like this with no luck -

Conditions -

    "EnvCheck": {
        "Fn::Not": [
            {"Fn::Equals": [{"Ref": "EnvironmentType"}, "prod"]}
        ]
    },
    "EnableDowntimeTag": {
        "Fn::And": [
            {"Fn::Equals": [{"Ref": "CustodianDowntime"}, "true"]},
            {"Condition": "EnvCheck"}
        ]
    }

Tags section

    "Tags": [
                {
                    "Key": "OwnerContact",
                    "PropagateAtLaunch": "true",
                    "Value": {
                        "Ref": "OwnerContact"
                    }
                },
                {
                    "Condition" : "EnableDowntimeTag",
                    "Key": "custodian_downtime",
                    "PropagateAtLaunch": "true",
                    "Value": "Offhours tz=ET"
                }
            ],

Any idea on how to add a conditional tag?

Thanks!

Answer 1

And if you're using YAML

  Tags:
    - 'Fn::If':
      - MyCondition
      -
        Key: MyKey
        Value: MyValue
      - !Ref AWS::NoValue

Answer 2

I have a similar need and don't want unused tags lying around either. I've gotten it working using the following snippet:

"Tags": [
  ...,
  {
    "Fn::If": [
      "MyCondition",
      {"Key": "MyKey", "Value": "MyValue"},
      {"Ref": "AWS::NoValue"}
    ]
  }
],