get prom working

cmd/trakr/main.go

@@ -2,17 +2,57 @@ package main
 
 import (
 	"errors"
+	"io/ioutil"
 	"log"
+	"net/http"
 	"os"
 	"os/signal"
 	"runtime/pprof"
 	"syscall"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/cobra"
+	"gopkg.in/yaml.v2"
 
 	"github.com/jzelinskie/trakr"
 )
 
+type ConfigFile struct {
+	Config struct {
+		PrometheusAddr string `yaml:"prometheus_addr"`
+		trakr.MultiTracker
+	} `yaml:"trakr"`
+}
+
+// ParseConfigFile returns a new ConfigFile given the path to a YAML
+// configuration file.
+//
+// It supports relative and absolute paths and environment variables.
+func ParseConfigFile(path string) (*ConfigFile, error) {
+	if path == "" {
+		return nil, errors.New("no config path specified")
+	}
+
+	f, err := os.Open(os.ExpandEnv(path))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	contents, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+
+	var cfgFile ConfigFile
+	err = yaml.Unmarshal(contents, &cfgFile)
+	if err != nil {
+		return nil, err
+	}
+
+	return &cfgFile, nil
+}
+
 func main() {
 	var configFilePath string
 	var cpuProfilePath string
@@ -33,19 +73,30 @@ func main() {
 					defer pprof.StopCPUProfile()
 				}
 
-				mt, err := trakr.MultiTrackerFromFile(configFilePath)
+				configFile, err := ParseConfigFile(configFilePath)
 				if err != nil {
 					return errors.New("failed to read config: " + err.Error())
 				}
 
+				go func() {
+					promServer := http.Server{
+						Addr:    configFile.Config.PrometheusAddr,
+						Handler: prometheus.Handler(),
+					}
+					log.Println("started serving prometheus stats on", configFile.Config.PrometheusAddr)
+					if err := promServer.ListenAndServe(); err != nil {
+						log.Fatal(err)
+					}
+				}()
+
 				go func() {
 					shutdown := make(chan os.Signal)
 					signal.Notify(shutdown, syscall.SIGINT, syscall.SIGTERM)
 					<-shutdown
-					mt.Stop()
+					configFile.Config.MultiTracker.Stop()
 				}()
 
-				if err := mt.ListenAndServe(); err != nil {
+				if err := configFile.Config.MultiTracker.ListenAndServe(); err != nil {
 					return errors.New("failed to cleanly shutdown: " + err.Error())
 				}