@aws-cdk/aws-synthetics: Canary within VPC won't delete ENI and its associated lambda when undeploy

[ynyany]

Describe the bug

1. put canary into VPC with an existing security group
2. deploy the canary
3. undeply the stack
4. stack failed to deconstruct lambda (of this canary cwyn-xx) and the ENI it created

if I manually remove the lambda and its ENI then the stack can be deleted.

Expected Behavior

Stack delete automatically including the lambda (behind the canary and its ENI created)

Current Behavior

can not delete the lambda (behind the canary and its ENI created) automatically

Reproduction Steps

1. put canary into VPC with an existing security group
2. deploy the canary
3. undeply the stack
4. stack failed to deconstruct lambda (of this canary cwyn-xx) and the ENI it created

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.42.1

Framework Version

No response

Node.js Version

14

OS

macos

Language

Typescript

Language Version

No response

Other information

No response

[peterwoodworth]

Could you provide reproduction code please @ynyany? You're using our L2 Canary construct or a CfnCanary?

[ynyany]

I am using L1 canary, but looked into L2 canary, it should be the same.

gitst of the canary code

 const allowLambdaSg = new cdk.aws_ec2.SecurityGroup(this, "SecurityGroup", {
      vpc: vpc,
      description: "Security group allowing lambda SG to access OPA ",
      allowAllOutbound: true,
    });
    const vpcConfig =  {
        vpcId: vpc.vpcId,
        subnetIds: vpc.privateSubnets.map((subnet) => subnet.subnetId),
        securityGroupIds: [allowLambdaSg.securityGroupId],
      };
 new synthetics.CfnCanary(this, "Canary", {
      artifactS3Location: artifactsBucket.bucket.s3UrlForObject(prefix),
      executionRoleArn: this.canaryRole.roleArn,
      runtimeVersion: props.runtime.name,
      name: props.canaryName,
      schedule: {
        expression: scheduleExpressString,
      },
      startCanaryAfterCreation: props.startAfterCreation ?? true,
      code: this.createCode(props.test),
      runConfig: {
        activeTracing: true,
        timeoutInSeconds: props.timeoutInSeconds ?? 15,
        environmentVariables: props.environmentVariables,
      },
      vpcConfig,
    });

where VPC is just a new vpc created by

 const subnets = [
      {
        cidrMask: 24,
        name: "PrivateSubnetA",
        subnetType: cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED,
      },
      {
        cidrMask: 24,
        name: "PublicSubnetA",
        subnetType: cdk.aws_ec2.SubnetType.PUBLIC,
      },
    ];

    const vpc = new cdk.aws_ec2.Vpc(this, "object-extension-Vpc", {
      gatewayEndpoints: {
        S3: { service: cdk.aws_ec2.GatewayVpcEndpointAwsService.S3 },
      },
      maxAzs: 2,
      natGatewayProvider: cdk.aws_ec2.NatProvider.gateway(),
      natGateways: 2,
      subnetConfiguration: subnets,
    });

nothing special, the CFN provided did not delete the lambda associated with the lambda, therefore the ENI. because of those behavious the whole stack can not be deleted.

[ynyany]

Furthermore, there's an AWS blog to similar issue (outside vpc) https://aws.amazon.com/blogs/mt/delete-amazon-cloudwatch-synthetics-dependent-resources-when-you-delete-a-cloudformation-stack/
this is blocking customer from properly delete our aws solution.

[kaizencc]

Hi @ynyany, this is not a CDK bug. The behavior you describe is how Canaries work -- when you delete the canary, you must manually delete the underlying resources on your own. There is an issue we're tracking for supporting this as a feature request: #18448 but we're not likely to take that up soon.

If you need an automated way to delete resources that come with your canary, my only suggestion is to follow the blog post you've linked and/or +1 the issue I've linked.

[github-actions]

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