Pub/Sub: Retries when publishing #20573

Environment details

• OS: Ubuntu
• Ruby version: 3.1.2
• Gem name and version: google-cloud-pubsub (2.15.1)

Steps to reproduce

Not sure if this is a bug or intended, but two things:

1. If an error happens during publishing, using the async publisher, it is not retried unless you also supply an ordering key:

rescue StandardError => e
  items = batch.items

  unless batch.ordering_key.empty?
    retry if publish_batch_error_retryable? e # why are retries only done when ordering key present?

This was added in: #3685. How come retrying in case of errors should not be done if you don't have an ordering key? Or is that a bug?

2. If you do have an ordering key, it will retry any of the following errors, indefinitely:

PUBLISH_RETRY_ERRORS = [
  GRPC::Cancelled, GRPC::DeadlineExceeded, GRPC::Internal,
  GRPC::ResourceExhausted, GRPC::Unauthenticated, GRPC::Unavailable
].freeze

Consulting the documentation (https://cloud.google.com/pubsub/docs/reference/error-codes) it looks like some of these are incorrect. For instance GRPC::Unauthenticated should not be retried, and GRPC::ResourceExhausted should be retried with exponential backoff. It seems like it would be a problem if for instance GRPC::Unauthenticated keeps retrying forever?