feat: add retry and dead letter topic behaviour, refs #8

[stefan-cardnell-rh]

No description provided.

[bodja]

Why does the first attempt need a special handling?

[bodja]

we could always return return f"{self.group_id}.{topic_name}.retry.{attempt}"

[stefan-cardnell-rh]

Depending on the attempt, msg.topic() can be different. For attempt 1, the msg.topic() is the original topic. For greater, msg.topic() is the retry topic ({self.group_id}.{topic_name}.retry.{attempt}). So depending on the attempt, I have to append retry.1, or regex sub the attempt numbers.

I have access to the main topic, but I can't do:

return {self.group_id}.{self.main_topic.name}.retry.{attempt}

Because self.main_topic.name may be regex hitting multiple topics, whereas I need a concrete topic name, not a regex, which means I need to get it from msg.topic().

I think maybe we should rename the name property because it gives the impression it's a concrete name and not possibly a regex. In Confluent Kafka it's just called topic. But if I put a topic property in the Topic class, we'd be accessing topic.topic a lot.

[stefan-cardnell-rh]

@bodja please review again, thanks!

[bodja]

lets rename this variable to smth else, to avoid conflicts when importing conf.settings