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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://web-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...")
}