Move sync.Leader to marathon module

README.md

@@ -207,6 +207,7 @@ marathon-protocol           | `http`          | Marathon protocol (http or https
 marathon-ssl-verify         | `true`          | Verify certificates when connecting via SSL
 marathon-timeout            | `30s`           | Time limit for requests made by the Marathon HTTP client. A Timeout of zero means no timeout
 marathon-username           |                 | Marathon username for basic auth
+marathon-leader             |                 | Marathon cluster-wide node name (defaults to <hostname>:8080), the some leader specific calls will be made only if the specified node is the current Marathon-leader")
 metrics-interval            | `30s`           | Metrics reporting interval
 metrics-location            |                 | Graphite URL (used when metrics-target is set to graphite)
 metrics-prefix              | `default`       | Metrics prefix (default is resolved to <hostname>.<app_name>

config/config.go

@@ -91,14 +91,14 @@ func (config *Config) parseFlags() {
 	// Sync
 	flag.BoolVar(&config.Sync.Enabled, "sync-enabled", true, "Enable Marathon-consul scheduled sync")
 	flag.DurationVar(&config.Sync.Interval.Duration, "sync-interval", 15*time.Minute, "Marathon-consul sync interval")
-	flag.StringVar(&config.Sync.Leader, "sync-leader", "", "Marathon cluster-wide node name (defaults to <hostname>:8080), the sync will run only if the specified node is the current Marathon-leader")
 	flag.BoolVar(&config.Sync.Force, "sync-force", false, "Force leadership-independent Marathon-consul sync (run always)")
 
 	// Marathon
 	flag.StringVar(&config.Marathon.Location, "marathon-location", "localhost:8080", "Marathon URL")
 	flag.StringVar(&config.Marathon.Protocol, "marathon-protocol", "http", "Marathon protocol (http or https)")
 	flag.StringVar(&config.Marathon.Username, "marathon-username", "", "Marathon username for basic auth")
 	flag.StringVar(&config.Marathon.Password, "marathon-password", "", "Marathon password for basic auth")
+	flag.StringVar(&config.Marathon.Leader, "marathon-leader", "", "Marathon cluster-wide node name (defaults to <hostname>:8080), the some leader specific calls will be made only if the specified node is the current Marathon-leader")
 	flag.BoolVar(&config.Marathon.VerifySsl, "marathon-ssl-verify", true, "Verify certificates when connecting via SSL")
 	flag.DurationVar(&config.Marathon.Timeout.Duration, "marathon-timeout", 30*time.Second, "Time limit for requests made by the Marathon HTTP client. A Timeout of zero means no timeout")
 

main.go

@@ -36,7 +36,7 @@ func main() {
 
 	consulInstance := consul.New(config.Consul)
 	// TODO(tz) - move Leader from sync module to highest level config, access like config.Leader
-	remote, err := marathon.New(config.Marathon, config.Sync.Leader)
+	remote, err := marathon.New(config.Marathon)
 	if err != nil {
 		log.Fatal(err.Error())
 	}

marathon/config.go

@@ -7,6 +7,7 @@ type Config struct {
 	Protocol  string
 	Username  string
 	Password  string
+	Leader    string
 	VerifySsl bool
 	Timeout   time.Interval
 }

marathon/marathon.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 	"time"
 
@@ -15,13 +16,15 @@ import (
 	"github.com/allegro/marathon-consul/metrics"
 )
 
+var hostname = os.Hostname
+
 type Marathoner interface {
 	ConsulApps() ([]*apps.App, error)
 	App(apps.AppID) (*apps.App, error)
 	Tasks(apps.AppID) ([]apps.Task, error)
 	Leader() (string, error)
 	EventStream([]string, int, int) (*Streamer, error)
-	AmILeader() (bool, error)
+	IsLeader() (bool, error)
 }
 
 type Marathon struct {
@@ -36,7 +39,7 @@ type LeaderResponse struct {
 	Leader string `json:"leader"`
 }
 
-func New(config Config, leader string) (*Marathon, error) {
+func New(config Config) (*Marathon, error) {
 	var auth *url.Userinfo
 	if len(config.Username) == 0 && len(config.Password) == 0 {
 		auth = nil
@@ -53,8 +56,8 @@ func New(config Config, leader string) (*Marathon, error) {
 	return &Marathon{
 		Location: config.Location,
 		Protocol: config.Protocol,
+		MyLeader: config.Leader,
 		Auth:     auth,
-		MyLeader: leader,
 		client: &http.Client{
 			Transport: transport,
 			Timeout:   config.Timeout.Duration,
@@ -142,7 +145,7 @@ func (m Marathon) leaderPoll() error {
 	retries := 5
 	i := 0
 	for range pollTicker {
-		leading, err := m.AmILeader()
+		leading, err := m.IsLeader()
 		if err != nil {
 			if i >= retries {
 				return fmt.Errorf("Failed to get a leader after %d retries", i)
@@ -244,7 +247,22 @@ func (m Marathon) urlWithQuery(path string, params params) string {
 	return marathon.String()
 }
 
-func (m Marathon) AmILeader() (bool, error) {
+func (m *Marathon) IsLeader() (bool, error) {
+	if m.MyLeader == "" {
+		if err := m.resolveHostname(); err != nil {
+			return false, fmt.Errorf("Could not resolve hostname: %v", err)
+		}
+	}
 	leader, err := m.Leader()
 	return m.MyLeader == leader, err
 }
+
+func (m *Marathon) resolveHostname() error {
+	hostname, err := hostname()
+	if err != nil {
+		return err
+	}
+	m.MyLeader = fmt.Sprintf("%s:8080", hostname)
+	log.WithField("Leader", m.MyLeader).Info("Marathon Leader mode set to resolved hostname")
+	return nil
+}

marathon/marathon_stub.go

@@ -11,6 +11,7 @@ type MarathonerStub struct {
 	AppsStub       []*apps.App
 	AppStub        map[apps.AppID]*apps.App
 	TasksStub      map[apps.AppID][]apps.Task
+	MyLeader       string
 	leader         string
 	interactionsMu sync.RWMutex
 	interactions   bool
@@ -46,8 +47,8 @@ func (m *MarathonerStub) EventStream([]string, int, int) (*Streamer, error) {
 	return &Streamer{}, nil
 }
 
-func (m *MarathonerStub) AmILeader() (bool, error) {
-	return false, nil
+func (m *MarathonerStub) IsLeader() (bool, error) {
+	return m.leader == m.MyLeader, nil
 }
 
 func (m *MarathonerStub) Interactions() bool {
@@ -62,9 +63,10 @@ func (m *MarathonerStub) noteInteraction() {
 	m.interactions = true
 }
 
-func MarathonerStubWithLeaderForApps(leader string, args ...*apps.App) *MarathonerStub {
+func MarathonerStubWithLeaderForApps(leader, myLeader string, args ...*apps.App) *MarathonerStub {
 	stub := MarathonerStubForApps(args...)
 	stub.leader = leader
+	stub.MyLeader = myLeader
 	return stub
 }
 
@@ -86,6 +88,7 @@ func MarathonerStubForApps(args ...*apps.App) *MarathonerStub {
 		AppsStub:  args,
 		AppStub:   appsMap,
 		TasksStub: tasksMap,
+		MyLeader:  "localhost:8080",
 		leader:    "localhost:8080",
 	}
 }

marathon/marathon_stub_test.go

@@ -11,7 +11,7 @@ import (
 func TestMarathonStub(t *testing.T) {
 	t.Parallel()
 	// given
-	m := marathon.MarathonerStubWithLeaderForApps("some.host:1234", utils.ConsulApp("/test/app", 3))
+	m := marathon.MarathonerStubWithLeaderForApps("some.host:1234", "some.host:1234", utils.ConsulApp("/test/app", 3))
 	// then
 	assert.False(t, m.Interactions())
 	// when