Bootstrap flag for connection limit overload manager resource monitor

[seth-epps]

Overview

Fixes #6309

Manual testing

Setting the configuration parameters for the enforced connection limit listener and the connection limits

diff --git a/examples/contour/01-contour-config.yaml b/examples/contour/01-contour-config.yaml
index 6eb7720b..d56b811c 100644
--- a/examples/contour/01-contour-config.yaml
+++ b/examples/contour/01-contour-config.yaml
@@ -184,3 +184,7 @@ data:
     #  socket-options:
     #    tos: 64
     #    traffic-class: 64
+    #
+    omEnforcedHealthListener:
+      address: 0.0.0.0
+      port: 8003
diff --git a/examples/contour/03-envoy.yaml b/examples/contour/03-envoy.yaml
index b9c71f39..6e4e474d 100644
--- a/examples/contour/03-envoy.yaml
+++ b/examples/contour/03-envoy.yaml
@@ -105,6 +105,7 @@ spec:
         - --envoy-cafile=/certs/ca.crt
         - --envoy-cert-file=/certs/tls.crt
         - --envoy-key-file=/certs/tls.key
+        - --overload-dowstream-max-conn=100 # arbitrary value
         command:
         - contour
         image: ghcr.io/projectcontour/contour:main

After running make install-contour-working

# kubectl -n projectcontour port-forward envoy-hq4bj 9001:9001
#
# check listener configs
#
# default stats listner (should ignore -- this is for liveness)
❯ curl -s localhost:9001/config_dump | jq '.configs[] |
  select(."@type" == "type.googleapis.com/envoy.admin.v3.ListenersConfigDump") |
  .dynamic_listeners[] | select(.name == "stats-health").active_state.listener |
  "port: \(.address.socket_address.port_value), ignore_conn_limit: \(.ignore_global_conn_limit)"'
"port: 8002, ignore_conn_limit: true"
#
# enforced connection limit listener (should enforce [null] -- this is for readiness)
#
❯ curl -s localhost:9001/config_dump | jq '.configs[] |
  select(."@type" == "type.googleapis.com/envoy.admin.v3.ListenersConfigDump") |
  .dynamic_listeners[] | select(.name == "health-om-enforced").active_state.listener |
  "port: \(.address.socket_address.port_value), ignore_conn_limit: \(.ignore_global_conn_limit)"'
"port: 8003, ignore_conn_limit: null"
#
# check bootstrap OM config
#
❯ curl -s localhost:9001/config_dump | jq '.configs[] | select(."@type" == "type.googleapis.com/envoy.admin.v3.BootstrapConfigDump") | .bootstrap.overload_manager'
{
  "refresh_interval": "0.250s",
  "resource_monitors": [
    {
      "name": "envoy.resource_monitors.global_downstream_max_connections",
      "typed_config": {
        "@type": "type.googleapis.com/envoy.extensions.resource_monitors.downstream_connections.v3.DownstreamConnectionsConfig",
        "max_active_downstream_connections": "100"
      }
    }
  ]
}

[codecov]

Codecov Report

Attention: Patch coverage is 96.39640% with 4 lines in your changes missing coverage. Please review.

Project coverage is 81.08%. Comparing base (da03924) to head (1680909).
Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/contour/contour.go	0.00%	3 Missing ⚠️
cmd/contour/serve.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6794      +/-   ##
==========================================
+ Coverage   81.05%   81.08%   +0.02%     
==========================================
  Files         133      133              
  Lines       20026    20073      +47     
==========================================
+ Hits        16232    16276      +44     
- Misses       3500     3503       +3     
  Partials      294      294              

Files with missing lines	Coverage Δ
cmd/contour/bootstrap.go	100.00% <100.00%> (ø)
cmd/contour/servecontext.go	84.54% <100.00%> (+0.03%)	⬆️
internal/envoy/bootstrap.go	57.14% <100.00%> (+4.87%)	⬆️
internal/envoy/v3/bootstrap.go	92.70% <100.00%> (+0.41%)	⬆️
internal/envoy/v3/stats.go	100.00% <100.00%> (ø)
internal/featuretests/v3/envoy.go	99.13% <100.00%> (+<0.01%)	⬆️
internal/featuretests/v3/featuretests.go	86.68% <100.00%> (+0.04%)	⬆️
internal/xdscache/v3/listener.go	91.98% <100.00%> (ø)
pkg/config/parameters.go	88.05% <ø> (ø)
cmd/contour/serve.go	21.74% <0.00%> (ø)
... and 1 more

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