[aws-rds] ParameterGroup is missing from CloudFormation template

Since version 1.58.0 ParameterGroup resources are missing from the generated CloudFormation template.

Reproduction Steps

• Create a new cdk app using version 1.51.0 and add the following code in the stack:

new ParameterGroup(this, "RDS-ParameterGroup", {
  family: "mysql:5.7",
});

• Run the cdk synth command and verify that the AWS::RDS::DBParameterGroup resource exists in the generated CloudFormation template.
• Now update cdk to version 1.58.0 and modify the ParameterGroup to:

new ParameterGroup(this, "RDS-ParameterGroup", {
  engine: DatabaseInstanceEngine.mysql({
    version: MysqlEngineVersion.VER_5_7,
  }),
});

• Run the cdk synth command and view the generated CloudFormation template. The AWS::RDS::DBParameterGroup resource is missing.

What did you expect to happen?

The AWS::RDS::DBParameterGroup resource should exist in both versions of aws cdk.

What actually happened?

The AWS::RDS::DBParameterGroup resource exists in version 1.51.0 but not in 1.58.0.

Environment

• CLI Version: 1.58.0
• Framework Version: 1.58.0
• Node.js Version: 14.5.0
• OS: Windows 10
• Language (Version): TypeScript (3.9.6)

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This is 🐛 Bug Report

[skinny85]

@lossanarch if you want to shoot me a quick PR (doesn’t have to be super polished, just a draft with the rough proposal is fine), I’d be down to discuss the concrete steps to fix this 😉.

[skinny85]

Hey @manospasj ,

yes, the issue is exactly what @Chriscbr said. Basically, the ParameterGroup class is used both for AWS::RDS::DBParameterGroup and AWS::RDS::DBClusterParameterGroup, and creates the correct underlying resource when it’s passed to Instance or Cluster, respectively.

Also, this line in the source code needs to be updated as it suggests that the ParameterGroup class can only create a AWS::RDS::DBParameterGroup resource. The AWS::RDS::DBClusterParameterGroup resource needs to be included.

Unfortunately, we can’t have multiple CloudFormation resource types there. But I’ll try to update the docs to make it sure it’s more clear.

(It also looks like right now, if you tried to call bindToInstance() and then bindToCluster() afterwards, it would just ignore the second call, and perhaps it should really throw an error - but that’s a separate issue.)

Nope, that is not the behavior currently. The second call, to bindToCluster(), will actually create the AWS::RDS::DBClusterParameterGroup. So you’ll have 2 groups, an AWS::RDS::DBParameterGroup and an AWS::RDS::DBClusterParameterGroup.