(ec2): Fails to create subnet with `fromSubnetAttributes` without `routeTableId`

Describe the bug

When I create a Subnet using ec2.Subnet.from_subnet_attributes and don’t specify a routeTableId, I’m getting the following warning:

[Warning at /euc1-dv-rest-alb-alb/subnet-0] No routeTableId was provided to the subnet at 'euc1-dv-rest-alb-alb/subnet-0'. Attempting to read its .routeTable.routeTableId will return null/undefined. (More info: https://github.com/aws/aws-cdk/pull/3171)

While this warning definitely serves it’s purpose, I’m missing the option to turn it off or acknowledge it when for example I anyway don’t have the intention to read the routeTableId of the subnet.

It is just spamming the console when running synth but also prevents me from using --strict.

Expected Behavior

This warning shouldn’t be there. at all.

Current Behavior

cdk synth produces said warning, regardless of whether you’re actually trying to read the routeTableId parameter or not.

Reproduction Steps

Just do this in one of your stacks.

ec2.Subnet.from_subnet_attributes(self, id="subnet", subnet_id='subnet-0123456789abcdef0')

Possible Solution

Either the routeTableId Parameter should be mandatory for ec2.Subnet.from_subnet_attributes or if it stays optional (which is probably the better solution) it should not automatically trigger a warning. Instead synth should fail if you omit the routeTableId parameter and try to read it later. Maybe an error message with similar content could be created if this happens.

Additional Information/Context

The line of code where this happens is https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk/aws-ec2/lib/vpc.ts#L2103.

CDK CLI Version

2.19.0 (build e0d3e62)

Framework Version

No response

Node.js Version

v14.19.0

OS

Ubuntu 20.04.3 LTS, Linux VIE-NOMPOS-MOB 5.10.60.1-microsoft-standard-WSL2 #1 SMP Wed Aug 25 23:20:18 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Language

Typescript, Python, .NET, Java, Go

Language Version

not relevant

Other information

No response

[jordan-brough]

This happens with ec2.Subnet.fromSubnetId as well, which doesn’t even have an option to specify a routeTableId.

My current terrible workaround to avoid warning spam:

const subnet = cdk.aws_ec2.Subnet.fromSubnetId(this, 'Subnet', 'subnet-XXX');
// hack to avoid warning spam
subnet.node._metadata = subnet.node._metadata.filter((item) =>
  item.type !== 'aws:cdk:warning' || !/No routeTableId was provided to the subnet/.test(item.data)
);

It would be great to have the warning (or an exception) only when routeTableId is read.

[petejewels]

Using dotnet , having same issue:

TaskSubnets = new SubnetSelection
                    {
                        Subnets = new[] {
                           Subnet.FromSubnetId(this, "subnet1", "subnet-64564"),
                            Subnet.FromSubnetId(this, "subnet2", "subnet-987987")
                        },
                        
                    },

If we are given warning we should have ability to add a route table id to theFromSubnetId these subnets use…