Access DbInstance from DbCluster so that I can grantConnect

[bestickley]

When I instantiate a DbCluster, I need to grant lambdas the ability to connect to the DB as I use IAM DB Auth. I have a custom resource that enables me to do this now, but native grantConnect was recently released. However, how can I access the DbInstance's on the cluster to use their grantConnect method?

Also, anyone know why grantConnect isn't available on DbCluster. That would be more convenient.

[peterwoodworth]

You can reference the reader and writer properties of a DBCluster to reference the instances. You should then be able to use grantConnect after referencing the instances through these properties.

Also, anyone know why grantConnect isn't available on DbCluster

How exactly do you imagine this would work? Feel free to create a feature request for this if you have a good idea on how it would work and think there's a good use case for it

[bestickley]

@peterwoodworth, can you show me in code how that would work? I don't see a reader or writer property on DatabaseCluster. See properties here. However, there are a writer and reader Construct Props. Here is the link. I tried instantiating them before I instantiate the DatabaseCluster but the only method available on IClusterInstance is bind. Example:

const writer = new ClusterInstance.serverlessV2("WriterInstance");
// writer.grantConnect() <- THIS DOESN'T WORK
const dbCluster = new DatabaseCluster(this, "DbCluster", {
  writer,
  ...
});

I see on DatabaseInstance that the grantConnect method is there, I guess my key question is how do I get a reference from DatabaseCluster?

[peterwoodworth]

Ack sorry, you want instanceIdentifiers. There was a bug with this currently though...

[bestickley]

@peterwoodworth, thanks for the response. Got it, so from my example above I can access dbCluster.instanceIdentifiers to get an array of strings of the identifiers. But what then? How do I get access to the DatabaseInstance class which has grantConnect method on it?

Also, re:

How exactly do you imagine this would work? Feel free to create a feature request for this if you have a good idea on how it would work and think there's a good use case for it

My end goal is to being able to grantConnect to Lambdas from my DB. I'd prefer not to have to call grantConnect twice (one for writer and read). Is that possible currently? Or will I have to call it twice?

[peterwoodworth]

Sorry, I didn't take the proper care when looking at this issue. I was in a rush, thank you for being patient with me.

I think we need to open a feature request for this. DatabaseCluster doesn't implement DatabaseInstance anywhere under the hood, so there are no DatabaseInstances to reference.

And you're right that it would be nice if DatabaseCluster had a method for this, or at least had properties that had methods for this. This would need to start to be implemented here I believe, though I'm not sure what the best way to expose it to the end user would be.

aws-cdk/packages/aws-cdk-lib/aws-rds/lib/aurora-cluster-instance.ts

Line 422 in 27dc8ff

class AuroraClusterInstance extends Resource implements IAuroraClusterInstance {

[bestickley]

Done: #26489
Thanks, @peterwoodworth!

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.