Add new firehose stream

[daynew]

I'm implementing a new feature which will use Firehose but to a different Kinesis stream than the one we are already using. The PR just adds the ability to target different streams.

• Update FirehoseClient.put_record to have a stream_name parameter so we can target different streams.
• Update FirehoseClient so it has separate buffers for each Kinesis stream.

Links

• Blocks https://github.com/code-dot-org/code-dot-org/pull/34421/files

Testing story

• Unit tests

Reviewer Checklist:

• Tests provide adequate coverage
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[wjordan]

Overall this looks good! It could be merged as-is to unblock work moving forward. Added a couple of (optional) syntax/style comments below just for potential polish.

[wjordan]

(optional) to reduce the diff (and/or to remove some curly braces) you could use Ruby's implicit conversion of keyword parameters into a hash passed as the last argument:

FirehoseClient.instance.put_record(FirehoseClient::ANALYSIS_EVENTS_STREAM_NAME,
  study: 'share_filtering'
  [...etc...]
)

[wjordan]

These names seem a bit verbose to me, I tend to prefer variables/constants passed around in business-logic code to be shorter/more readable based on context. How about something like a fixed hash to lookup the full stream name based on a short symbol, e.g.:

STREAMS = {
  analysis: 'analysis-events',
  i18n: 'i18n-string-tracking-events'
}

def put_record(stream, data)
  stream_name = STREAMS[stream] || raise "Stream #{stream} not found"
  [...]
end

FirehoseClient.instance.put_record(:i18n,
  url: 'http://studio.code.org/courses',
  string_key: 'home.heading_elementary_markdown'
)

[wjordan]

I think this comment was already obsolete (and doubly so with this refactoring).

[wjordan]

You can make a keyword argument required (and even better, caught at compile-time) by removing the default value, e.g.:

def initialize(stream_name:)