CDK: There are no 'Private' subnet groups in this VPC after private group is deployed

user_1251549 0
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I have deployed rivate subnets in default vpc (java):

var stack = new Stack(app, "system-resource", StackProps.builder().env(env).build());
final IVpc vpc = Vpc.fromLookup(stack, "default-vpc", VpcLookupOptions.builder().isDefault(true).build());
final AtomicInteger index = new AtomicInteger();
var zones = stack.getAvailabilityZones();
var subnets = zones.stream().map(z -> {
  var subnet = new PrivateSubnet(stack, "priavte-subnet-" + index.getAndIncrement(), PrivateSubnetProps.builder()
      .vpcId(vpc.getVpcId())
      .cidrBlock(String.format(cidrTemplate, start.get()))
      .availabilityZone(z)
      .build());
  start.addAndGet(increment);
  return subnet;
}).collect(Collectors.toList());

Then I tried to use SubnetSelection:

final IVpc vpc = Vpc.fromLookup(this, "default-vpc", VpcLookupOptions.builder().isDefault(true).build());
final SubnetSelection vpcSubnets = SubnetSelection.builder().subnetType(SubnetType.PRIVATE).build();

And got exception:

An exception occured while executing the Java class. There are no 'Private' subnet groups in this VPC. Available types: Public

[ERROR] Error: There are no 'Private' subnet groups in this VPC. Available types: Public

How it determine a VPC to select from?

Why all my PrivateSubnets which had created before are "marketed" as public and can no be selected?

amazon-vpc aws-cdk java
2 Answers

In my case, I was using a VPC created in CDK itself with only ISOLATED subnets.

const vpc = new ec2.Vpc(this, 'private_vpc', {
    subnetConfiguration: [
        {
            name: 'application-subnet',
            subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
        }
    ]
});

I got this error when I tried to create a StepFunction task for ECS.

    const task = new sfnTasks.EcsRunTask(this, 'my_task', {
        integrationPattern: sfn.IntegrationPattern.WAIT_FOR_TASK_TOKEN,
        containerOverrides: [{
                containerDefinition: myContainerDefinition,
        }],
        cluster,mytextExtractionTaskDefinition,
        launchTarget: new sfnTasks.EcsFargateLaunchTarget(),
        securityGroups: [vpcSecurityGroup],
    });

The fix was to specify the subnets explicitly.

    const subnets = vpc.selectSubnets({
        subnetType: ec2.SubnetType.PRIVATE_ISOLATED
    }).subnets;

    const task = new sfnTasks.EcsRunTask(this, 'my_task', {
        integrationPattern: sfn.IntegrationPattern.WAIT_FOR_TASK_TOKEN,
        containerOverrides: [{
                containerDefinition: myContainerDefinition,
        }],
        cluster,mytextExtractionTaskDefinition,
        launchTarget: new sfnTasks.EcsFargateLaunchTarget(),
        subnets: subnets, // <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ADDED
        securityGroups: [vpcSecurityGroup],
    });
user_100455460

fromLookup method used to find an existing (already deployed) VPC in your account, when you define a VPC in CDK code you need to use the object you just created.

see docs:

static fromLookup(scope, id, options) Import an existing VPC from by querying the AWS environment this stack is deployed to.

This function only needs to be used to use VPCs not defined in your CDK application. If you are looking to share a VPC between stacks, you can pass the Vpc object between stacks and use it as normal.

user_89271350
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