Feature: Add a metrics endpoint

Add a basic Prometheus Monitoring metrics endpoint.
* Include a `jetkvm_build_info` metric.
* `go mod tidy`

Signed-off-by: SuperQ <superq@gmail.com>

web.go

@@ -12,6 +12,10 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
+	"github.com/prometheus/client_golang/prometheus"
+	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/prometheus/common/version"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -85,6 +89,11 @@ func setupRouter() *gin.Engine {
 	// We use this to setup the device in the welcome page
 	r.POST("/device/setup", handleSetup)
 
+	// A Prometheus metrics endpoint.
+	version.Version = builtAppVersion
+	prometheus.MustRegister(versioncollector.NewCollector("jetkvm"))
+	r.GET("/metrics", gin.WrapH(promhttp.Handler()))
+
 	// Protected routes (allows both password and noPassword modes)
 	protected := r.Group("/")
 	protected.Use(protectedMiddleware())