EKS Replace is not detected in CDK Diff

[moofish32]

EKS cluster can be destroyed and recreated and is not identified in the cdk diff output.

environment

• cdk version 0.13.0 using typescript

Reproduction:

Pull master and checkout the tag linked, then deploy the EksCluster stack: https://github.com/moofish32/cdk-eks-example/tree/cdk-diff-error

After deploy checkout this branch: https://github.com/moofish32/cdk-eks-example/tree/subent-change

Then run

npm run build
cdk diff EksCluster

I see the following:

[~] ⚠️ Replacing EksVpcEksPublicSubnet1SubnetD03B4EAC (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.0.0/24
     └─ [+] New value: 10.0.0.0/25
[~] ⚠️ Replacing EksVpcEksPublicSubnet2SubnetE53D1D54 (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.1.0/24
     └─ [+] New value: 10.0.0.128/25
[~] ⚠️ Replacing EksVpcEksPublicSubnet3SubnetE7B525D4 (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.2.0/24
     └─ [+] New value: 10.0.1.0/25
[~] ⚠️ Replacing EksVpcEksPrivateSubnet1SubnetA4B4FCC4 (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.8.0/21
     └─ [+] New value: 10.0.4.0/22
[~] ⚠️ Replacing EksVpcEksPrivateSubnet2SubnetA3E0468E (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.16.0/21
     └─ [+] New value: 10.0.8.0/22
[~] ⚠️ Replacing EksVpcEksPrivateSubnet3SubnetCEB45BC0 (type: AWS::EC2::Subnet)
 └─ [~] .CidrBlock (requires replacement):
     ├─ [-] Old value: 10.0.24.0/21
     └─ [+] New value: 10.0.12.0/22

However when deployed you can verify the EKS cluster is destroyed and recreated. Based on CFN I think this makes sense because subnet IDs are not updatable.

[rix0rrr]

I have a fix for this on a branch. Stay tuned.