Optional metrics JSON dumping/loading

Author: grussorusso

internal/config/keys.go

@@ -68,6 +68,12 @@ const METRICS_PROMETHEUS_PUSHGATEWAY_HOST = "metrics.prometheus.pushgateway.host
 // Interval (in seconds) for metrics retriever
 const METRICS_RETRIEVER_INTERVAL = "metrics.retriever.interval"
 
+// Filename to dump retrieved metrics as JSON
+const METRICS_DUMP_JSON_FILE = "metrics.dump.json.file"
+
+// Filename to load metrics from JSON
+const METRICS_LOAD_JSON_FILE = "metrics.load.json.file"
+
 // Scheduling policy to use
 // Possible values: "qosaware", "default", "cloudonly"
 const SCHEDULING_POLICY = "scheduler.policy"

internal/metrics/metrics.go

@@ -1,9 +1,11 @@
 package metrics
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/prometheus/client_golang/prometheus/push"
 	"log"
+	"os"
 	"time"
 
 	"net/http"
@@ -134,7 +136,29 @@ func Init() {
 
 	}
 
-	go MetricsRetriever()
+	jsonMetricsToLoad := config.GetString(config.METRICS_LOAD_JSON_FILE, "")
+	if jsonMetricsToLoad == "" {
+		go MetricsRetriever()
+	} else {
+		log.Println("Disabling metrics retriever and loading metrics from:", jsonMetricsToLoad)
+		err := loadMetricsFromJSON(jsonMetricsToLoad)
+		if err != nil {
+			log.Printf("Error loading metrics: %v\n", err)
+		}
+		log.Println(retrievedMetrics)
+	}
+}
+
+func loadMetricsFromJSON(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	decoder := json.NewDecoder(file)
+	err = decoder.Decode(&retrievedMetrics)
+	return err
 }
 
 func AddCompletedInvocation(funcName string, coldStart bool) {

internal/metrics/retriever.go

@@ -2,9 +2,11 @@ package metrics
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"github.com/serverledge-faas/serverledge/internal/registration"
 	"log"
+	"os"
 	"time"
 
 	"github.com/prometheus/common/model"
@@ -231,8 +233,24 @@ func MetricsRetriever() {
 				retrievedMetrics.AvgRemoteInitTime = make(map[string]float64)
 			}
 
-			fmt.Println("All queries completed")
 			fmt.Println(retrievedMetrics)
+
+			// TODO: configuration option
+			metricsJsonFilename := config.GetString(config.METRICS_DUMP_JSON_FILE, "")
+			if metricsJsonFilename != "" {
+				file, err := os.Create(metricsJsonFilename)
+				if err != nil {
+					log.Printf("Error in serializing metrics: %v", err)
+				} else {
+					encoder := json.NewEncoder(file)
+					encoder.SetIndent("", "  ") // Optional: for pretty printing
+					err = encoder.Encode(retrievedMetrics)
+					if err != nil {
+						log.Printf("Error in writing metrics to file: %v", err)
+					}
+					file.Close()
+				}
+			}
 		}
 	}
 

scripts/start-pushgateway.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-docker run -d -p 9091:9091 --name pushgateway prom/pushgateway
+docker run --rm -d -p 9091:9091 --name pushgateway prom/pushgateway