AWS CDK - how to create bulk thing with certs using CDK - aws-cdk

Question

i can create thing, policy, certificate and connect altogether with these steps similar to https://github.com/aws/aws-cdk/issues/19303
But I want to do that with bulk thing creation, create certs and with policy (have created policy etc)
How do i achieve with CDK ?
i tried using provisioning template, but i am a bit unsure about that.
my code
const iotAssumeRoleWithCertificatePolicy = new iot.CfnPolicy(this, 'iotAssumeRoleWithCertificatePolicy', {
policyName: 'iotAssumeRoleWithCertificatePolicy',
policyDocument: {
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "iot:AssumeRoleWithCertificate",
"Resource": iotRoleAlias.roleArn.toString(),
}
]
},
});
const provisioningTemplateBody = {
"Parameters": {
"ThingName": {
"Type": "String"
},
"CSR": {
"Type": "String"
},
},
"Resources": {
"thing": {
"Type": "AWS::IoT::Thing",
"Properties": {
"ThingName": { "Ref": "ThingName" },
"ThingTypeName": "server-type",
"ThingGroups": [
"server-group",
]
}
},
"certificate": {
"Type": "AWS::IoT::Certificate",
"Properties": {
"CertificateSigningRequest": { "Ref": "CSR" },
CertificateId: {
Ref: 'AWS::IoT::Certificate::Id',
},
"Status": "ACTIVE"
}
},
"policy": {
"Type": "AWS::IoT::Policy",
"Properties": {
"PolicyName": iotAssumeRoleWithCertificatePolicy.toString(),
}
}
}
}
const provisiongTemplate = new iot.CfnProvisioningTemplate(this, 'iot-provisioning-template', {
provisioningRoleArn: iotProvisioningRole.roleArn,
templateBody: JSON.stringify(provisioningTemplateBody),
});