aws_rds: unable to use per-instance parameters

[jessecollier]

Describe the bug

When trying to use the parameters property during ClusterInstance.provisioned, it will try to create a ParameterGroup for you using the id InstanceParameterGroup.

If you try to have multiple instances (ie multiple readers) in a DatabaseCluster, this will throw error:

Error: There is already a Construct with name 'InstanceParameterGroup' in DatabaseCluster [Database]

Here's the specific line of code:
https://github.com/aws/aws-cdk/blob/v2.94.0/packages/aws-cdk-lib/aws-rds/lib/aurora-cluster-instance.ts#L457-L464

Expected Behavior

I should be able to provide a simple parameters object and a parameter group to be created for each unique instance.

Current Behavior

Throws an error

Reproduction Steps

Create a DatabaseCluster with multiple readers with the parameters: {} property set:

ClusterInstance.provisioned(`Instance${id}`, {
         parameters: {}
    });

Possible Solution

The ParameterGroup scope is the cluster, either the scope should be specific to the ClusterInstance, or the ParameterGroup should have a unique ID.

Additional Information/Context

No response

CDK CLI Version

2.94.0

Framework Version

No response

Node.js Version

18

OS

mac osx latest

Language

Typescript

Language Version

No response

Other information

No response

[jessecollier]

This is my current work-around to be compatible with how it was created using instanceProps

const cluster = new DatabaseCluster();
const numberOfInstances = 3
const paramGroup = new ParameterGroup(
      cluster,
      'InstanceParameterGroup',
      {
        engine: cluster.engine!,
        parameters: {},
      },
    );

    for (let i = 0; i < (numberOfInstances ?? 1); i++) {
      const instance = cluster.node.findChild(
        `Instance${i + 1}`,
      ) as CfnDBInstance;
      instance.addOverride(
        'Properties.DBParameterGroupName',
        paramGroup.bindToInstance({}).parameterGroupName,
      );
    }

[peterwoodworth]

Makes sense, thanks for the report

[github-actions]

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