Backport of cmd: add CLI flags for proxy shutdown lifecycle management into release/1.0.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #100 to be assessed for backporting due to the inclusion of the label backport/1.0.

The below text is copied from the body of the original PR.

---

Refs hashicorp/consul-k8s#536, hashicorp/consul-k8s#650

Adds the following CLI flags for proxy shutdown lifecycle management, disabled by default:

• -shutdown-drain-listeners
• -shutdown-grace-period

Adds the following CLI flags for managing where the proxy lifecycle HTTP APIs are exposed:

• -graceful-shutdown-path
• -graceful-port

Notes for reviewers

• It looks like pkg/consuldp/consul_dataplane_test.go has tests exclusively for required configuration, should optional flags like those being added in this PR be tested somewhere else?
  • These flags are however tested implicitly by followup work in proxy-lifecycle: add HTTP Server with endpoints for proxy lifecycle shutdown #115, proxy-lifecycle: catch SIGTERM and initiate graceful shutdown #130 and helm: add configuration for proxy lifecycle management consul-k8s#2233 which exercise the full functionality.
• envoy/proxy_test.go looks like a reasonable places to check the actual graceful shutdown behavior once implemented (and if enabled), but too broad a scope for just checking the flags set configuration properly.
  • This has been used to test proxy-lifecycle: catch SIGTERM and initiate graceful shutdown #130
• Should this wait to merge until the underlying functionality for these flags is implemented?
  • No longer a relevant question as implementation is complete and pending review.
  • proxy-lifecycle: add HTTP Server with endpoints for proxy lifecycle shutdown #115
  • proxy-lifecycle: catch SIGTERM and initiate graceful shutdown #130
• Consul on ECS implements similar functionality through the -shutdown-delay CLI flag, do we care about the naming discrepancy? The implemented functionality may differ slightly because of how we'll be handling connection draining...

---

Overview of commits

• 9eaffd8 - 8568158 - e6f39b7 - ecfe23f - 04e73f2 - bd4d480 - c687111