Amplify custom resource

import * as AmplifyHelpers from '@aws-amplify/cli-extensibility-helper';
import * as ev from '@aws-cdk/aws-events';
import * as et from '@aws-cdk/aws-events-targets';
import * as lambda from '@aws-cdk/aws-lambda';
import * as ssm from '@aws-cdk/aws-ssm';
import * as cdk from '@aws-cdk/core';
import * as cr from '@aws-cdk/custom-resources';

import { AmplifyDependentResourcesAttributes } from '../../types/amplify-dependent-resources-ref';

export class cdkStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps, amplifyResourceProps?: AmplifyHelpers.AmplifyResourceProps) {
    super(scope, id, props);

    // CloudFormation complains if I move this in values-stack with
    // "Parameter values specified for a template which does not require them."
    new cdk.CfnParameter(this, 'env', {
      type: 'String',
      description: 'Current Amplify CLI env name',
    });

    const busName = new ssm.StringParameter(this, `reservationbusname`, {
      stringValue: `busname`,
      dataType: ssm.ParameterDataType.TEXT,
    }).stringValue;

    const ruleName = new ssm.StringParameter(this, `reservationrulename`, {
      stringValue: `busrule`,
      dataType: ssm.ParameterDataType.TEXT,
    }).stringValue;

    const sourcePar = new ssm.StringParameter(this, `reservationbussourcename`, {
      stringValue: `my.source`,
      dataType: ssm.ParameterDataType.TEXT
    });

    const source = sourcePar.stringValue;

    const deps: AmplifyDependentResourcesAttributes = AmplifyHelpers.addResourceDependency(this,
      amplifyResourceProps.category,
      amplifyResourceProps.resourceName,
      [
        { category: "function", resourceName: "lambda1" },
        { category: "function", resourceName: "lambda2" }
      ]
    );

    const lambda1Arn = cdk.Fn.ref(deps.function.lambda1.Arn);
    const lambda2Arn = cdk.Fn.ref(deps.function.lambda1.Arn);

    const eventBus = new ev.EventBus(this, `reservationbus`, {
      eventBusName: busName
    });

    const lambda1 = lambda.Function.fromFunctionArn(this,
      `lambda1id`,
      lambda1Arn);

    eventBus.grantPutEventsTo(lambda1);

    const lambda2 = lambda.Function.fromFunctionAttributes(this, `lambda2`, {
      functionArn: lambda2Arn,
      sameEnvironment: true
    });

    const rule = new ev.Rule(this, `rule-id`, {
      ruleName: ruleName,
      eventBus: eventBus,
      eventPattern: {
        source: [source],
      },
      targets: [
        new et.LambdaFunction(lambda1)
      ],
    });

    et.addLambdaPermission(rule, lambda1);

  }
}