aws-cdk-lib.aws_rds: instance update impossible - collides with storage configuration

[schabe77]

Describe the bug

Hi,

I switched my database cluster to the storage configuration mode AURORA_IOPT1 3 weeks ago.

Now I tried to change the instance type. This is my changeset:

Resources
[~] AWS::RDS::DBInstance rds-instance/db-cluster/db-writer rdsinstancedbclusterdbwriterDA345B19
 └─ [~] DBInstanceClass
     ├─ [-] db.r6g.xlarge
     └─ [+] db.serverless
[~] AWS::RDS::DBInstance rds-instance/db-cluster/reader-1 rdsinstancedbclusterreader193075C02
 └─ [~] DBInstanceClass
     ├─ [-] db.r6g.xlarge
     └─ [+] db.serverless

but when I try to deploy the change this error(s) occur:

10:40:13 | UPDATE_FAILED        | AWS::RDS::DBCluster                         | rdsinstancedbcluster1749B05D
Resource handler returned message: "You can't modify the storage type of this DB cluster yet. Try again after 2023-10-02T06:46:24.564Z. (Service: Rds, Status Code: 400, Request ID: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX)" (RequestToken: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX, HandlerErrorCode: InvalidRequest)
10:40:19 | UPDATE_FAILED        | AWS::RDS::DBCluster                         | rdsinstancedbcluster1749B05D
Resource handler returned message: "You can't modify the storage type of this DB cluster yet. Try again after 2023-10-02T06:46:24.564Z. (Service: Rds, Status Code: 400, Request ID: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX)" (RequestToken: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX, HandlerErrorCode: InvalidRequest)

I my opinion this operation should work, even though I'm still in the mandatory 1 month keep-storage-configuration-period. I don't want to modify the storage configuration, just the instance types. When I do the change via the management console, everything works fine.

Is it possible, that the modify-instance case was not considered when the storage configuration was introduced to cdk (as far as I can see with #25629)? Maybe the modify process tries to set the default storage type on update?

Expected Behavior

I wan't to be able to modify my instance type, even if I'm currently not allowed to change the storage type

Current Behavior

I'm unabel to change the database instance types

Reproduction Steps

create a database cluster, switch storage type, then try to modify the instance type or add a new instance

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.96.2 (build 3edd240)

Framework Version

No response

Node.js Version

v20.6.1

OS

macOs Ventura 13.5 (22G74)

Language

Java

Language Version

OpenJDK Runtime Environment Corretto-17.0.8.8.1 (build 17.0.8.1+8-LTS)

Other information

No response

[pahud]

So it sounds like you just modified the storage type from console and now you are trying to update the instance type with CDK but failed with the error?

even though I'm still in the mandatory 1 month keep-storage-configuration-period
Can you explain where this restriction comes from?

[schabe77]

No, I first tried it with cdk - this failed. Then I tried it via Management Console and this worked.

The question regarding the restriction is a good one. When I switched to I/O Optimized there was a warning that it's only possible to switch once per month. I have assumed that this is applied to both directions, but according to this documentation it should be possible to switch back to Aurora Standard at any time: "You can switch from Aurora I/O-Optimized to Aurora Standard at any time.", "You can switch from Aurora Standard to Aurora I/O-Optimized once every 30 days.".

This makes the error message even more confusing.

[samhopwell]

I'm also running into this issue while changing a security group of an RDS cluster that was deployed with AURORA_IOPT1.

Within the console the cluster is still showing as configured as AURORA_IOPT1 however during a cdk deploy it fails with "You can't modify the storage type of this DB cluster yet." despite there not being any storage changes listed.

If I remove storage_type from the DatabaseCluster construct this deploys as expected. It is still showing as AURORA_IOPT1 within the console also

[cajual]

This is an issue for us as well. We've have to introduce custom logic to allow our users to make changes to a database that has aurora-iopt1 enabled.