Infra sample bicep template should be idempotent

[jmal1]

infra/main.bicep currently defines a seed:

@description('Random seed to be used during generation of new resources suffixes.')
param seed string = newGuid()

The result is that re-running the bicep template (with or without updates) will create an entirely new RG and infra stack, rather than updating existing resources. This violates the idempotent and deterministic properties of bicep/ARM templates

Instead, the user should provide the suffix to be used when creating the resources. This will allow users to reuse the samples as there are more updates or as they make modifications.

I'm thinking something like:

param suffix string // no default value. This template should not be valid without a valid suffix.

[howieleung]

Thanks for your feedback. We initially did what you said. But it quickly get into some concern such as easily get into naming conflict when some resource name needed to be unique across other resource groups. And some resource naming cannot have certain characters, but bicep does not return naming policy when error occur. We believe GUID has a better success rate for deployment

[jmal1]

That makes sense, but maybe there's a better solution where we can keep the ARM/bicep re-deployment properties? How about something like this?

param seedValue string // a seed phrase provided by the user. Maybe something like "jmal1AIDeployment1"

var suffix = substring(uniqueString(seedValue), 0, 8) // produces an 8-character string that can be used when naming the RG and resources

I know it requires an input from the user, but someone who isn't familiar with working with templates might really be scratching their head when the basic idempotent properties of templated deployments don't apply in what's basically a quickstart for using templates

[aprilk-ms]

No matter what we do. Idempotency is important.
Other than ad hoc azd up during testing, users will also use azd to deploy their infrastructure: https://github.com/Azure-Samples/get-started-with-ai-agents/blob/main/.github/workflows/azure-dev.yml
We cannot have new resources created every time.

[howieleung]

We now don't use newGuid.