Resolve GCP Pub/Sub subscription or topic name from the target's environment

[jtymes]

Proposal

The GCP Pub/Sub scaler currently allows defining the subscriptionName or the topicName. I'd like to propose adding subscriptionNameFromEnv and topicNameFromEnv. This will work similarly to the AWS SQS Scaler's queueURLFromEnv.

Use-Case

We have subscriptions that vary by region for the same workload for storing into their respective datastores. The name of the subscription is provided to the workload in each region through a ConfigMap. Using the resolved environment simplifies the ScaledObjects we need to deploy.

Is this a feature you are interested in implementing yourself?

Yes

Anything else?

No response