Bind the health check service to localhost

[stephen-soltesz]

This change updates the default -health_addr to explicitly bind to localhost:8000 to prevent accidentally exposing this service to the public internet. This change should have not effect since the heartbeat service already targets localhost unconditionally

Part of:

• https://github.com/m-lab/ops-tracker/issues/1798

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This change is 

[nkinkade]

with one comment, possibly needing no action.

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on @stephen-soltesz)

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ndt-server.go line 41 at r1 (raw file):

	ndt5WsAddr        = flag.String("ndt5_ws_addr", "127.0.0.1:3002", "The address and port to use for the ndt5 WS test")
	ndt5WssAddr       = flag.String("ndt5_wss_addr", ":3010", "The address and port to use for the ndt5 WSS test")
	healthAddr        = flag.String("health_addr", "localhost:8000", "The address and port to use for health checks")

Could this use 127.0.0.1 instead, to be consistent with the value for ndt5WsAddr? Or will using localhost cause it to bind to both the IPv4 and IPv6 loopback addresses?

[stephen-soltesz]

Reviewable status: complete! 1 of 1 approvals obtained (waiting on @nkinkade)

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ndt-server.go line 41 at r1 (raw file):

Previously, nkinkade wrote…

Could this use 127.0.0.1 instead, to be consistent with the value for ndt5WsAddr? Or will using localhost cause it to bind to both the IPv4 and IPv6 loopback addresses?

That's a very good call. I've updated to use 127.0.0.1.