Fix panic when no master could be parsed

Fixes #19

CHANGELOG.md

@@ -13,7 +13,8 @@ Improvements:
 
 Bug Fixes:
 * [Docs] Syntax error in example configuration file of HAProxy
-* [Marathon] Fix ServiceGenerator only picks the first server in the list [#16](https://github.com/wndhydrnt/proxym/issues/16).
+* [Marathon] Fix ServiceGenerator only picks the first server in the list [#16](https://github.com/wndhydrnt/proxym/issues/16)
+* [Mesos Master] Fix panic when no master could be parsed [#19](https://github.com/wndhydrnt/proxym/issues/19)
 
 ## 1.4.0
 

marathon/generator.go

@@ -6,12 +6,11 @@ import (
 	"fmt"
 	"github.com/wndhydrnt/proxym/log"
 	"github.com/wndhydrnt/proxym/types"
+	"github.com/wndhydrnt/proxym/utils"
 	"io/ioutil"
-	"math/rand"
 	"net/http"
 	"strconv"
 	"strings"
-	"time"
 )
 
 // Generator talks to Marathon and creates a list of services as a result.
@@ -26,7 +25,7 @@ func (g *Generator) Generate() ([]*types.Service, error) {
 	var apps Apps
 	var tasks Tasks
 
-	server := pickRandomServer(g.marathonServers)
+	server := utils.PickRandomFromList(g.marathonServers)
 
 	log.AppLog.Debug("Querying Marathon server at '%s'", server)
 
@@ -155,18 +154,3 @@ func normalizeId(id string, port int) string {
 
 	return "marathon_" + strings.Join(parts, "_") + "_" + strconv.Itoa(port)
 }
-
-func pickRandomServer(servers []string) string {
-	if len(servers) == 1 {
-		return servers[0]
-	}
-
-	src := rand.NewSource(time.Now().UnixNano())
-	r := rand.New(src)
-
-	max := (len(servers) * 100) - 1
-
-	pick := float64(r.Intn(max)) / 100
-
-	return servers[int(pick)]
-}

mesos_master/mesos_master.go

@@ -3,10 +3,12 @@ package mesos_master
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"github.com/kelseyhightower/envconfig"
 	"github.com/wndhydrnt/proxym/log"
 	"github.com/wndhydrnt/proxym/manager"
 	"github.com/wndhydrnt/proxym/types"
+	"github.com/wndhydrnt/proxym/utils"
 	"io/ioutil"
 	"math/rand"
 	"net/http"
@@ -46,7 +48,13 @@ type state struct {
 }
 
 func parseLeader(leader string) (types.Host, error) {
-	address := strings.Split(leader, "@")[1]
+	pidParts := strings.Split(leader, "@")
+
+	if len(pidParts) != 2 {
+		return types.Host{}, errors.New(fmt.Sprintf("Unable to parse Mesos Master PID %s", leader))
+	}
+
+	address := pidParts[1]
 
 	parts := strings.Split(address, ":")
 
@@ -90,10 +98,10 @@ func query(hc *http.Client, master string) (string, error) {
 	return state.Leader, nil
 }
 
-func leader(hc *http.Client, masters string) (types.Host, error) {
+func leader(hc *http.Client, masters []string) (types.Host, error) {
 	var host types.Host
 
-	master := pickMaster(masters)
+	master := utils.PickRandomFromList(masters)
 
 	leaderId, err := query(hc, master)
 	if err != nil {
@@ -131,15 +139,13 @@ func init() {
 			return
 		}
 
-		hc := &http.Client{}
 		lr := &leaderRegistry{
 			mutex: &sync.Mutex{},
 		}
 
-		n := &MesosMasterNotifier{
-			config:         &c,
-			hc:             hc,
-			leaderRegistry: lr,
+		n, err := NewMesosNotifier(&c, lr)
+		if err != nil {
+			log.ErrorLog.Fatal(err)
 		}
 		manager.AddNotifier(n)
 

mesos_master/notifier.go

@@ -1,9 +1,11 @@
 package mesos_master
 
 import (
+	"errors"
 	"github.com/wndhydrnt/proxym/log"
 	"github.com/wndhydrnt/proxym/types"
 	"net/http"
+	"strings"
 	"sync"
 	"time"
 )
@@ -13,6 +15,7 @@ type MesosMasterNotifier struct {
 	currentLeader  types.Host
 	hc             *http.Client
 	leaderRegistry *leaderRegistry
+	masters        []string
 }
 
 func (m *MesosMasterNotifier) Start(refresh chan string, quit chan int, wg *sync.WaitGroup) {
@@ -29,9 +32,9 @@ func (m *MesosMasterNotifier) Start(refresh chan string, quit chan int, wg *sync
 }
 
 func (m *MesosMasterNotifier) pollLeader(refresh chan string) {
-	host, err := leader(m.hc, m.config.Masters)
+	host, err := leader(m.hc, m.masters)
 	if err != nil {
-		log.ErrorLog.Error("Error getting current Mesos Master leader: '%s'", err)
+		log.ErrorLog.Error("Error getting current Mesos Master leader: %s", err)
 		return
 	}
 
@@ -47,3 +50,14 @@ func (m *MesosMasterNotifier) pollLeader(refresh chan string) {
 
 	m.currentLeader = host
 }
+
+func NewMesosNotifier(c *Config, lr *leaderRegistry) (*MesosMasterNotifier, error) {
+	hc := &http.Client{}
+	masters := strings.Split(c.Masters, ",")
+
+	if len(masters) == 0 {
+		return nil, errors.New("PROXYM_MESOS_MASTER_MASTERS is not set")
+	}
+
+	return &MesosMasterNotifier{config: c, hc: hc, leaderRegistry: lr, masters: masters}, nil
+}

mesos_master/notifier_test.go

@@ -45,14 +45,13 @@ func TestShouldTriggerRefreshWhenMasterChanges(t *testing.T) {
 		mutex: &sync.Mutex{},
 	}
 
-	n := MesosMasterNotifier{
-		config: &Config{
+	n, _ := NewMesosNotifier(
+		&Config{
 			Masters:      ts.URL,
 			PollInterval: 1,
 		},
-		hc:             &http.Client{},
-		leaderRegistry: lr,
-	}
+		lr,
+	)
 
 	go n.Start(refresh, make(chan int), wg)
 

utils/utils.go

@@ -0,0 +1,21 @@
+package utils
+
+import (
+	"math/rand"
+	"time"
+)
+
+func PickRandomFromList(list []string) string {
+	if len(list) == 1 {
+		return list[0]
+	}
+
+	src := rand.NewSource(time.Now().UnixNano())
+	r := rand.New(src)
+
+	max := (len(list) * 100) - 1
+
+	pick := float64(r.Intn(max)) / 100
+
+	return list[int(pick)]
+}