Add prometheus instrumentation, count active ws conns (#8)

* Add prometheus instrumentation, count active ws conns

* Stop bum ticker

* Moving things around

* Handle unspecified host for ws proxy

* Add config reload counter

* metrics: rename conns -> players

internal/quake/client/router.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 
 	quakenet "github.com/criticalstack/quake-kube/internal/quake/net"
 )
@@ -52,6 +53,8 @@ func NewRouter(cfg *Config) (*echo.Echo, error) {
 		})
 	})
 
+	e.GET("/metrics", echo.WrapHandler(promhttp.Handler()))
+
 	e.GET("/info", func(c echo.Context) error {
 		m, err := quakenet.GetInfo(cfg.ServerAddr)
 		if err != nil {