Add a separate HTTP listener for observability, configured through
metricsServer in both frps and frpc. It serves /healthz and, when
pprofEnable is set, the pprof handlers except /debug/pprof/cmdline. It
never serves the dashboard, static assets or the admin API, and it does
not touch the global assets filesystem.
frps also serves /metrics on this listener with both runtime and business
metrics, enabled by metricsServer.port alone. The in-memory collector
still starts only with the dashboard, and the Prometheus collector starts
either with metricsServer or with enablePrometheus plus webServer, so a
configuration that collected nothing before still collects nothing.
The /healthz, /metrics and pprof endpoints on webServer, and
enablePrometheus, keep working but are deprecated and log a hint at
startup. frpc does not serve /metrics yet.
A constructor that binds a port before its fallible preparation leaks the
listener when a later step returns an error, and no one can close it because
the returned service is nil.
pkg/util/http: load the TLS keypair and build the auth middleware before
net.Listen, so binding is the last step that can run and a failure leaves no
bound port behind.
server: create the web server after auth, the tcpmux, main, kcp, quic, ssh
gateway and vhost listeners, and the nat hole controller, following what frpc
already does. If the web server itself fails, close the resources created so
far before returning. The port managers start their cleanup workers on
creation, so they are created after every fallible step too, and the metrics
collectors keep being enabled only when the web server is configured.
Add regression tests for all three failure paths.
fatedier