Ambassador Module considered harmful

[kflynn]

The Module concept in Emissary is a relic from its very early days that we've been slowly removing. The last holdout is the ambassador Module, and really, it's time to get rid of it:

• Most of its configuration can be moved into the Listener:
  • allow_chunked_length, enable_http10, envoy_log stuff, and proper_case are all great examples here: they're really characteristics of a Listener, not the whole system.
  • Having a way to set a global default for these probably still makes sense.
• Some of its configuration really should be supported in a properly-typed CRD:
  • admin_port and diagnostics come to mind here.
  • Global defaults as noted above.

The obvious solution here is a pass of moving most things into Listener, and creating a GlobalConfig CRD for the few things that should truly be global.

[irl-segfault]

big +1

[rbtcollins]

Tracing is perhaps a global characteristic - certainly the driver that is used and the sink to send spans too. I can imagine a per-listener fragment, with svc id and the like.