Support Managed identity auth for Blob Storage checkpointing in Event Hub scaler

[andyatwork]

Proposal

Accessing the blob storage for Event Hubs requires a connection string to be supplied by means of triggers.metadata.storageConnectionFromEnv . azure_eventhub_checkpoint.go could be modified to pass the PodIdentity from EventHubInfo with the required account name and endpoint to enable pod identity based authentication.

Suggest to pass PodIdentity to ParseAzureStorageBlobConnection and add fields to trigger.metadata:

• StorageAccountName - The name of the account

StorageEndpointSuffix is internally resolved from Azure's environment configuration for the specified cloud.

The fqdn blob storage uri is compiled from https://{StorageAccountName}.blob.{StorageEndpointSuffix}/ .

Use-Case

Allowing pod identities to be used consistently across Event Hub and Storage Accounts enables connection string free configurations and eliminates the need to manually manage a connection credential.

Anything else?

When using the above configuration together with a triggers.authenticationRef, the field storageConnectionFromEnv is no longer required.

To preserve back-compat, if storageConnectionFromEnv is provided, it will force connection string based authN for the blob storage account.

[andyatwork]

I'd be happy to contribute this feature to the project.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[v-shenoy]

Completed in #3573.