Adding tracking of game server states as gauges

Signed-off-by: Ken Haines <1144092+khaines@users.noreply.github.com>

nodeagent/main.go

@@ -46,12 +46,8 @@ func main() {
 	// starts the server in a goroutine
 	startHttpServer(srv)
 
-	// create a channel and wait for SIGINT or SIGTERM
-	sig := make(chan os.Signal, 1)
-	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
-	<-sig
-	log.Info("Shutting down")
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	// wait for SIGINT or SIGTERM
+	ctx, cancel := waitForShutdownSignal()
 	defer cancel()
 
 	// shut down gracefully, but wait no longer than 5 seconds before halting
@@ -65,8 +61,16 @@ func healthzHandler(w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte("OK"))
 }
 
+func waitForShutdownSignal() (context.Context, context.CancelFunc) {
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+	<-sig
+	log.Info("Shutting down")
+	return context.WithTimeout(context.Background(), 5*time.Second)
+}
+
 func getEnv(key string, required bool) string {
-	if value, ok := os.LookupEnv(key); !ok {
+	if value, ok := os.LookupEnv(key); ok {
 		return value
 	}
 	if required {

nodeagent/nodeagentmanager.go

@@ -11,6 +11,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
 	log "github.com/sirupsen/logrus"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -32,6 +34,13 @@ const (
 	LabelNodeName       = "NodeName"
 )
 
+var (
+	GameServerStates = promauto.NewGaugeVec(prometheus.GaugeOpts{
+		Name: "game_server_states",
+		Help: "Game server states",
+	}, []string{"name", "state"})
+)
+
 type NodeAgentManager struct {
 	gameServerMap *sync.Map // we use a sync map instead of a regular map since this will be updated by multiple goroutines
 	dynamicClient dynamic.Interface
@@ -142,6 +151,11 @@ func (n *NodeAgentManager) gameServerUpdated(oldObj, newObj interface{}) {
 
 	gsd := gsdi.(*GameServerDetails)
 
+	GameServerStates.WithLabelValues(gameServerName, newState).Set(1)
+	if gsd.PreviousGameState != "" {
+		GameServerStates.WithLabelValues(gameServerName, string(gsd.PreviousGameState)).Set(0)
+	}
+
 	// we're only interested if the game server was allocated
 	if gsd.PreviousGameState == GameStateStandingBy && newState == string(GameStateActive) {
 		sessionID, sessionCookie := n.parseSessionDetails(new, gameServerName, gameServerNamespace)