Implement proxier healthcheck in Antrea agent.

[shettyg]

With kube-proxy, external load-balancers check to see whether the node LB is healthy by doing a healthcheck on kube-proxy on port 10256. kube-proxy in turn returns back the time when the most recent update happened on dataplane.

e.g: curl.exe http://127.0.0.1:10256/healthz {"lastUpdated": "2022-08-18 16:16:11.6510411 +0000
GMT m=+257377.633892701",
"currentTime": "2022-08-18 16:16:11.6510411 +0000
GMT m=+257377.633892701"}

In kube-proxy replacement mode, antrea does not support this feature. This becomes more important for Windows support as userspace kube-proxy is being deprecated.

This commit implements this feature in Antrea and is inspired by the same feature in upstream kube-proxy.

Signed-off-by: Guru Shetty [email protected]

[shettyg]

CC: @jianjuns @tnqn @hongliangl

This is the next step after service health implementation. There is still a TODO item in the code, but I wanted early comments whether you are fine with something like this in Antrea proxy.

[codecov[bot]]

Codecov Report

Merging #4196 (559f3e4) into main (5dfdf24) will increase coverage by 0.30%. The diff coverage is 47.82%.

@@            Coverage Diff             @@
##             main    #4196      +/-   ##
==========================================
+ Coverage   60.32%   60.62%   +0.30%     
==========================================
  Files         380      384       +4     
  Lines       53798    54384     +586     
==========================================
+ Hits        32452    32972     +520     
- Misses      18922    18966      +44     
- Partials     2424     2446      +22     

Flag	Coverage Δ
integration-tests	34.73% <0.00%> (-0.16%)	:arrow_down:
kind-e2e-tests	48.92% <78.57%> (-0.64%)	:arrow_down:
unit-tests	41.74% <0.00%> (+0.52%)	:arrow_up:

Impacted Files	Coverage Δ
cmd/antrea-agent/agent.go	0.00% <0.00%> (ø)
pkg/agent/proxy/proxier.go	66.95% <78.57%> (+0.92%)	:arrow_up:
...lowaggregator/clickhouseclient/clickhouseclient.go	73.59% <0.00%> (-9.13%)	:arrow_down:
pkg/agent/controller/networkpolicy/reject.go	73.50% <0.00%> (-7.50%)	:arrow_down:
pkg/flowaggregator/options/options.go	31.25% <0.00%> (-5.49%)	:arrow_down:
pkg/controller/networkpolicy/tier.go	50.00% <0.00%> (-5.00%)	:arrow_down:
pkg/agent/openflow/service.go	88.04% <0.00%> (-3.27%)	:arrow_down:
...gent/controller/networkpolicy/status_controller.go	78.99% <0.00%> (-2.53%)	:arrow_down:
pkg/flowaggregator/flowaggregator.go	67.56% <0.00%> (-2.49%)	:arrow_down:
pkg/agent/flowexporter/utils.go	82.97% <0.00%> (-2.13%)	:arrow_down:
... and 32 more

[github-actions[bot]]

This PR is stale because it has been open 90 days with no activity. Remove stale label or comment, or this will be closed in 90 days

[github-actions[bot]]

This PR is stale because it has been open 90 days with no activity. Remove stale label or comment, or this will be closed in 90 days