redis: add support for stream commands (xread, xadd etc)

[danielnorberg]

Title: Redis stream command support

Description:
Envoy should proxy stream commands instead of responding "unsupported command".

This would be useful when utilizing redis streams via an envoy proxy.

Most of the stream commands only take a single key and can be trivially routed to the appropriate shard.

Some stream commands (e.g. XREAD and XREADGROUP) take multiple keys. A reasonable behavior could be to route the entire command to the shard corresponding to the first key in the arguments. Cluster-mode redis instances will reject commands where not all keys map to the same shard. However, non-cluster mode redis instances (sharded over by envoy) would not reject such commands. To catch this case envoy itself would need to verify that all keys of the command shard to the same instance.

Relevant Links:

• Redis Streams: https://redis.io/docs/data-types/streams/
• Stream commands: https://redis.io/commands/?group=stream

[nezdolik]

cc @msukalski @weisisea

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as "help wanted" or "no stalebot". Thank you for your contributions.