feat: add runtime modification of log level using config file

cmd/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"log"
 
+	"github.com/fsnotify/fsnotify"
 	"github.com/go-playground/validator/v10"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
@@ -88,6 +89,7 @@ func init() {
 
 	if err := v.ReadInConfig(); err != nil {
 		log.Printf("Unable to read config file, %v", err)
+		isConfigFileAvailable = false
 	}
 
 	log.Printf("Get raw config: %+v", v.AllSettings())
@@ -101,3 +103,12 @@ func (c *UpfConfig) Validate() error {
 func (c *UpfConfig) Unmarshal() error {
 	return v.UnmarshalExact(c)
 }
+
+var isConfigFileAvailable bool = true
+
+func WatchConfig(onConfigChange func(e fsnotify.Event)) {
+	if isConfigFileAvailable {
+		viper.OnConfigChange(onConfigChange)
+		viper.WatchConfig()
+	}
+}

cmd/config/startup.go

@@ -18,3 +18,19 @@ func Init() {
 
 	log.Printf("Apply eUPF config: %+v", Conf)
 }
+
+func ReadConfig() (UpfConfig, error) {
+	var conf UpfConfig
+	if err := conf.Unmarshal(); err != nil {
+		log.Fatalf("Unable to decode into struct, %v", err)
+		return UpfConfig{}, err
+	}
+
+	if err := conf.Validate(); err != nil {
+		log.Fatalf("eUPF config is invalid: %v", err)
+		return UpfConfig{}, err
+	}
+
+	log.Printf("Read config: %+v", conf)
+	return conf, nil
+}

cmd/core/api.go

@@ -36,18 +36,18 @@ func CreateApiServer(bpfObjects *ebpf.BpfObjects, pfcpSrv *PfcpConnection, forwa
 		v1.GET("upf_pipeline", ListUpfPipeline(bpfObjects))
 		v1.GET("xdp_stats", DisplayXdpStatistics(forwardPlaneStats))
 		v1.GET("packet_stats", DisplayPacketStats(forwardPlaneStats))
-    
-    config := v1.Group("config")
+
+		config := v1.Group("config")
 		{
 			config.GET("", DisplayConfig())
-			config.POST("", EditConfig)
+			config.POST("", UpdateConfig)
 		}
-		
-    pdrMap := v1.Group("uplink_pdr_map")
+
+		pdrMap := v1.Group("uplink_pdr_map")
 		{
 			pdrMap.GET(":id", GetUplinkPdrValue(bpfObjects))
 			pdrMap.PUT(":id", SetUplinkPdrValue(bpfObjects))
-    }	
+		}
 
 		qerMap := v1.Group("qer_map")
 		{
@@ -79,7 +79,7 @@ func CreateApiServer(bpfObjects *ebpf.BpfObjects, pfcpSrv *PfcpConnection, forwa
 	return &ApiServer{router: router}
 }
 
-func EditConfig(c *gin.Context) {
+func UpdateConfig(c *gin.Context) {
 	var conf config.UpfConfig
 	if err := c.BindJSON(&conf); err != nil {
 		c.IndentedJSON(http.StatusBadRequest, gin.H{
@@ -90,7 +90,7 @@ func EditConfig(c *gin.Context) {
 	}
 	if err := SetConfig(conf); err != nil {
 		c.IndentedJSON(http.StatusBadRequest, gin.H{
-			"message": fmt.Sprintf("Error during editing config: %s", err.Error()),
+			"message": fmt.Sprintf("Error during updating config: %s", err.Error()),
 		})
 	} else {
 		c.Status(http.StatusOK)

cmd/main.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/edgecomllc/eupf/cmd/core"
 	"github.com/edgecomllc/eupf/cmd/ebpf"
+	"github.com/fsnotify/fsnotify"
 
 	"github.com/cilium/ebpf/link"
 	"github.com/edgecomllc/eupf/cmd/config"
@@ -107,6 +108,9 @@ func main() {
 		}
 	}()
 
+	// Handle config file change.
+	config.WatchConfig(OnConfigFileChange)
+
 	// Print the contents of the BPF hash map (source IP address -> packet count).
 	ticker := time.NewTicker(5 * time.Second)
 	defer ticker.Stop()
@@ -139,3 +143,13 @@ func StringToXDPAttachMode(Mode string) link.XDPAttachFlags {
 		return link.XDPGenericMode
 	}
 }
+
+func OnConfigFileChange(e fsnotify.Event) {
+	if e.Has(fsnotify.Create) || e.Has(fsnotify.Write) {
+		if conf, err := config.ReadConfig(); err == nil {
+			if err := core.SetConfig(conf); err != nil {
+				log.Error().Msgf("Error during config file change handling: %s", err.Error())
+			}
+		}
+	}
+}