[Core] support complex types in Fn.conditionIf

I am using the CDK to output a raw CloudFormation template as a final deliverable and am using primarily Cfn* resource constructs. We have a CfnPipeline object where I want to conditionally add a stage depending on a CfnParameter value. I have the following code:

codepipeline = aws_codepipeline.CfnPipeline(
            self,
            "Pipeline",
            artifact_store=aws_codepipeline.CfnPipeline.ArtifactStoreProperty(...),
                type="S3"
            ),
            role_arn=codepipeline_role.role_arn,
            stages=[
                aws_codepipeline.CfnPipeline.StageDeclarationProperty(...),
                aws_codepipeline.CfnPipeline.StageDeclarationProperty(...),
                aws_codepipeline.CfnPipeline.StageDeclarationProperty(...),
                core.Fn.condition_if(
                    cloudfront_enable_condition.logical_id,
                    aws_codepipeline.CfnPipeline.StageDeclarationProperty(
                        name="Finalize",
                        actions=[
                            aws_codepipeline.CfnPipeline.ActionDeclarationProperty(
                                action_type_id=aws_codepipeline.CfnPipeline.ActionTypeIdProperty(
			            category="Invoke",
                                    owner="AWS",
                                    provider="Lambda",
                                    version="1"
                                ),
                                configuration={
                                    "FunctionName": cloudfront_invalidation_lambda_function.ref
                                },
                                name="CloudFrontInvalidationAction",
                                role_arn=codepipeline_finalize_stage_role.attr_arn
                            )
                        ]
                    ),
                    core.Aws.NO_VALUE
                )
            ]
)

Which produces the following output in my CloudFormation template:

          {
            "Fn::If": [
              "CloudFrontEnableCondition",
              {
                "actions": [
                  {
                    "actionTypeId": {
                      "category": "Invoke",
                      "owner": "AWS",
                      "provider": "Lambda",
                      "version": "1"
                    },
                    "name": "CloudFrontInvalidationAction",
                    "configuration": {
                      "FunctionName": {
                        "Ref": "CloudFrontInvalidationLambdaFunction"
                      }
                    },
                    "roleArn": {
                      "Fn::GetAtt": [
                        "CodePipelineFinalizeStageRole",
                        "Arn"
                      ]
                    }
                  }
                ],
                "name": "Finalize"
              },
              {
                "Ref": "AWS::NoValue"
              }
            ]
          }
        ]

The keys of the CfnPipeline.StageDeclarationProperty and its children (CfnPipeline.ActionDeclarationProperty and CfnPipeline.ActionTypeIdProperty) are printed in camelCase, making for invalid CloudFormation objects on submission. I’ve also tried by wrapping the conditional statement in core.Token.as_any() with the same result.

I have resorted to using the following code:

codepipeline.add_override(
            "Properties.Stages.3",
            {
                "Fn::If": [
                    cloudfront_enable_condition.logical_id,
                    {
                        "Actions": [
                            {
                                "ActionTypeId": {
                                    "Category": "Invoke",
                                    "Owner": "AWS",
                                    "Provider": "Lambda",
                                    "Version": 1
                                },
                                "Configuration": {
                                    "FunctionName": cloudfront_invalidation_lambda_function.ref
                                },
                                "Name": "CloudFrontInvalidationAction",
                                "RoleArn": codepipeline_finalize_stage_role.attr_arn
                            }
                        ],
                        "Name": "Finalize"
                    },
                    core.Aws.NO_VALUE
                ]
            }
        )

which fixes my issue and proves that my conditional is valid in CloudFormation, but it feels messy and like the Cfn* properties should be supported in conditionals (IResolvable?).

Feels like this is a bug, but might be a feature request – perhaps something is missing in the translation layer between nodejs and the Python API? If I’m supposed to be using the API differently, please advise.

Reproduction Steps

Run the above code patterns and inspect the cloudformation template in cdk.out

Error Log

CloudFormation complains of invalid object syntax.

Environment

• CLI Version : 1.42.1
• Framework Version:
• Node.js Version: 12.16.2
• OS : Ubuntu
• Language (Version): Python3

Other

https://github.com/ordinaryexperts/aws-marketplace-oe-patterns-drupal/blob/f0201c49583a553832d72267ba07850b1bbe4aca/cdk/drupal/drupal_stack.py#L1870

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This is 🐛 Bug Report

[acarlton]

I will reopen this issue for reference but I will reiterate that the happy path for CDK is writing ifs in TypeScript, not in CloudFormation.

@rix0rrr Thanks for reconsidering. A reminder that the use case presented in the ticket description is using Cfn* resources to generate a CloudFormation template final deliverable and the suggested happy path of doing if statements in TypeScript or Python isn’t an option for us.

[rix0rrr]

I will reopen this issue for reference but I will reiterate that the happy path for CDK is writing ifs in TypeScript, not in CloudFormation.