[FIXED] How to map from InstanceClass enum to actual AWS instance types

Issue

I am trying to deploy a DocumentDB instance using AWS CDK docdb package (Java) and I keep getting this error:

Invalid DB Instance class: db.d2.large (Service: AmazonRDS; Status Code: 400; Error Code: InvalidParameterValue; Request
ID: 41494b4b-d14f-46ff-b077-9ee73aad515f; Proxy: null)

I know that, for example, an r5.large would work, but I cannot find a way to map from the InstanceType enum values (STANDARDx, STORAGE2, etc.) to the actual AWS Instance type; it does not appear to be documented anywhere, and the example (in TypeScript) use happily something like instanceType: 'r5.large' and move on.

This is my code, for completeness:

    DatabaseCluster dbCluster = DatabaseCluster.Builder.create(scope, "ApiDocDb")
        .dbClusterName(dataProps.getTableName())
        .masterUser(Login.builder()
            .username(masterUsername)
            .password(SecretValue.plainText(masterPwd))
            .build())
        .instanceType(InstanceType.of(InstanceClass.STORAGE2, InstanceSize.LARGE))
        .vpc(Vpc.Builder.create(scope, "DocDB-VPC")
            .cidr("10.2.0.0/16")
            .build())
        .vpcSubnets(SubnetSelection.builder().subnetType(SubnetType.PUBLIC).build())
        .build();

Solution

By trial and error (largely) I finally arrived at this:

        .instanceType(InstanceType.of(InstanceClass.MEMORY5, InstanceSize.LARGE))

which seems to work. Some help from this page - cross-correlating with the fact that, in the console, if one tries to add an instance, only r5 are allowed in the drop-down.

I just wish AWS had documented that enum a bit better.

Answered By - Marco Massenzio