Imported github.com/ardanlabs/service as base example project

example-project/cmd/sidecar/metrics/main.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	_ "net/http/pprof"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"geeks-accelerator/oss/saas-starter-kit/example-project/cmd/sidecar/metrics/collector"
+	"geeks-accelerator/oss/saas-starter-kit/example-project/cmd/sidecar/metrics/publisher"
+	"geeks-accelerator/oss/saas-starter-kit/example-project/cmd/sidecar/metrics/publisher/expvar"
+	"github.com/kelseyhightower/envconfig"
+)
+
+func main() {
+
+	// =========================================================================
+	// Logging
+
+	log := log.New(os.Stdout, "TRACER : ", log.LstdFlags|log.Lmicroseconds|log.Lshortfile)
+	defer log.Println("main : Completed")
+
+	// =========================================================================
+	// Configuration
+
+	var cfg struct {
+		Web struct {
+			DebugHost       string        `default:"0.0.0.0:4001" envconfig:"DEBUG_HOST"`
+			ReadTimeout     time.Duration `default:"5s" envconfig:"READ_TIMEOUT"`
+			WriteTimeout    time.Duration `default:"5s" envconfig:"WRITE_TIMEOUT"`
+			ShutdownTimeout time.Duration `default:"5s" envconfig:"SHUTDOWN_TIMEOUT"`
+		}
+		Expvar struct {
+			Host            string        `default:"0.0.0.0:3001" envconfig:"HOST"`
+			Route           string        `default:"/metrics" envconfig:"ROUTE"`
+			ReadTimeout     time.Duration `default:"5s" envconfig:"READ_TIMEOUT"`
+			WriteTimeout    time.Duration `default:"5s" envconfig:"WRITE_TIMEOUT"`
+			ShutdownTimeout time.Duration `default:"5s" envconfig:"SHUTDOWN_TIMEOUT"`
+		}
+		Collect struct {
+			From string `default:"http://sales-api:4000/debug/vars" envconfig:"FROM"`
+		}
+		Publish struct {
+			To       string        `default:"console" envconfig:"TO"`
+			Interval time.Duration `default:"5s" envconfig:"INTERVAL"`
+		}
+	}
+
+	if err := envconfig.Process("METRICS", &cfg); err != nil {
+		log.Fatalf("main : Parsing Config : %v", err)
+	}
+
+	cfgJSON, err := json.MarshalIndent(cfg, "", "    ")
+	if err != nil {
+		log.Fatalf("main : Marshalling Config to JSON : %v", err)
+	}
+	log.Printf("config : %v\n", string(cfgJSON))
+
+	// =========================================================================
+	// Start Debug Service. Not concerned with shutting this down when the
+	// application is being shutdown.
+	//
+	// /debug/pprof - Added to the default mux by the net/http/pprof package.
+	go func() {
+		log.Printf("main : Debug Listening %s", cfg.Web.DebugHost)
+		log.Printf("main : Debug Listener closed : %v", http.ListenAndServe(cfg.Web.DebugHost, http.DefaultServeMux))
+	}()
+
+	// =========================================================================
+	// Start expvar Service
+
+	exp := expvar.New(log, cfg.Expvar.Host, cfg.Expvar.Route, cfg.Expvar.ReadTimeout, cfg.Expvar.WriteTimeout)
+	defer exp.Stop(cfg.Expvar.ShutdownTimeout)
+
+	// =========================================================================
+	// Start collectors and publishers
+
+	// Initialize to allow for the collection of metrics.
+	collector, err := collector.New(cfg.Collect.From)
+	if err != nil {
+		log.Fatalf("main : Starting collector : %v", err)
+	}
+
+	// Create a stdout publisher.
+	// TODO: Respect the cfg.publish.to config option.
+	stdout := publisher.NewStdout(log)
+
+	// Start the publisher to collect/publish metrics.
+	publish, err := publisher.New(log, collector, cfg.Publish.Interval, exp.Publish, stdout.Publish)
+	if err != nil {
+		log.Fatalf("main : Starting publisher : %v", err)
+	}
+	defer publish.Stop()
+
+	// =========================================================================
+	// Shutdown
+
+	// Make a channel to listen for an interrupt or terminate signal from the OS.
+	// Use a buffered channel because the signal package requires it.
+	shutdown := make(chan os.Signal, 1)
+	signal.Notify(shutdown, os.Interrupt, syscall.SIGTERM)
+	<-shutdown
+
+	log.Println("main : Start shutdown...")
+}