From 1a0350adf188068ab11afc738ba5b1e5b4945401 Mon Sep 17 00:00:00 2001
From: Frank Kloeker <f.kloeker@telekom.de>
Date: Mon, 27 Mar 2023 15:45:55 +0200
Subject: [PATCH] WIP: init prometheus

---
 api/api.go   |  2 ++
 main.go      | 16 ++++++++++++++++
 mesh/mesh.go |  2 ++
 3 files changed, 20 insertions(+)

diff --git a/api/api.go b/api/api.go
index 9c0aab5..1397383 100644
--- a/api/api.go
+++ b/api/api.go
@@ -39,6 +39,7 @@ import (
 	connect "github.com/bufbuild/connect-go"
 	grpc_zap "github.com/grpc-ecosystem/go-grpc-middleware/logging/zap"
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/telekom/canary-bot/data"
 	h "github.com/telekom/canary-bot/helper"
 	"github.com/telekom/canary-bot/proto/api/third_party"
@@ -133,6 +134,7 @@ func StartApi(data data.Database, config *Configuration, log *zap.SugaredLogger)
 
 	mux.Handle(apiv1connect.NewApiServiceHandler(a, interceptors))
 	mux.Handle("/api/v1/", gwmux)
+	mux.Handle("/metrics", promhttp.Handler())
 	server := &http.Server{
 		Addr:              addr,
 		Handler:           h2c.NewHandler(mux, &http2.Server{}),
diff --git a/main.go b/main.go
index c5a080c..b9d5edb 100644
--- a/main.go
+++ b/main.go
@@ -33,12 +33,28 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
 )
 
 const (
 	envPrefix = "MESH"
 )
 
+// prometheus metrics for nodes and samples and cluster
+
+var (
+	nodecounts = promauto.NewGauge(prometheus.GaugeOpts{
+		Name: "mesh_nodes",
+		Help: "The total number of nodes",
+	})
+	samplecounts = promauto.NewGauge(prometheus.GaugeOpts{
+		Name: "mesh_samples",
+		Help: "The total number of samples",
+	})
+)
+
 var cmd = &cobra.Command{
 	Use:   "cbot",
 	Short: "Canary Bot collecting & distributing sample data in a mesh",
diff --git a/mesh/mesh.go b/mesh/mesh.go
index b6392e6..c781855 100644
--- a/mesh/mesh.go
+++ b/mesh/mesh.go
@@ -145,6 +145,8 @@ func CreateCanaryMesh(routineConfig *RoutineConfiguration, setupConfig *SetupCon
 		CaCert:         setupConfig.CaCert,
 	}
 
+	// init prometheus metrics to fetch data from database
+
 	// start the mesh API
 	if err = api.StartApi(database, apiConfig, logger.Named("api")); err != nil {
 		logger.Fatal("Could not start API - Error: %+v", err)