ENH: Adds support for multiple listeners (#35)

Author: thomasjpfan

Dockerfile

@@ -28,6 +28,7 @@ ENV CERTS="" \
     LISTENER_ADDRESS="" \
     MODE="default" \
     PROXY_INSTANCE_NAME="docker-flow" \
+    RELOAD_ATTEMPTS="5" \
     RELOAD_INTERVAL="5000" REPEAT_RELOAD=false \
     RECONFIGURE_ATTEMPTS="20" \
     SEPARATOR="," \

Dockerfile.linux-arm

@@ -19,6 +19,7 @@ ENV CERTS="" \
     LISTENER_ADDRESS="" \
     MODE="default" \
     PROXY_INSTANCE_NAME="docker-flow" \
+    RELOAD_ATTEMPTS="5" \
     RELOAD_INTERVAL="5000" REPEAT_RELOAD=false \
     RECONFIGURE_ATTEMPTS="20" \
     SEPARATOR="," \

actions/fetch.go

@@ -1,11 +1,12 @@
 package actions
 
 import (
-	"../proxy"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"strings"
+
+	"../proxy"
 )
 
 // Fetchable defines interface that fetches information from other sources
@@ -46,6 +47,7 @@ func (m *fetch) ReloadConfig(baseData BaseReconfigure, listenerAddr string) erro
 	if err = json.NewDecoder(resp.Body).Decode(&services); err != nil {
 		return err
 	}
+
 	needsReload := false
 	for _, s := range services {
 		proxyService := proxy.GetServiceFromMap(&s)

args.go

@@ -1,8 +1,9 @@
 package main
 
 import (
-	"github.com/jessevdk/go-flags"
 	"os"
+
+	"github.com/jessevdk/go-flags"
 )
 
 type args struct{}

args_test.go

@@ -4,10 +4,11 @@ package main
 
 import (
 	"fmt"
-	"github.com/stretchr/testify/suite"
 	"net/http"
 	"os"
 	"testing"
+
+	"github.com/stretchr/testify/suite"
 )
 
 type ArgsTestSuite struct {
@@ -49,6 +50,7 @@ func (s ArgsTestSuite) Test_Parse_ParsesServerLongArgs() {
 	for _, d := range data {
 		s.Equal(d.expected, *d.value)
 	}
+	s.Len(serverImpl.ListenerAddresses, 1)
 }
 
 func (s ArgsTestSuite) Test_Parse_ParsesServerShortArgs() {
@@ -69,12 +71,11 @@ func (s ArgsTestSuite) Test_Parse_ParsesServerShortArgs() {
 	for _, d := range data {
 		s.Equal(d.expected, *d.value)
 	}
+	s.Len(serverImpl.ListenerAddresses, 1)
 }
 
 func (s ArgsTestSuite) Test_Parse_ServerHasDefaultValues() {
 	os.Args = []string{"myProgram", "server"}
-	os.Unsetenv("IP")
-	os.Unsetenv("PORT")
 	data := []struct {
 		expected string
 		value    *string
@@ -87,6 +88,7 @@ func (s ArgsTestSuite) Test_Parse_ServerHasDefaultValues() {
 	for _, d := range data {
 		s.Equal(d.expected, *d.value)
 	}
+	s.Len(serverImpl.ListenerAddresses, 1)
 }
 
 func (s ArgsTestSuite) Test_Parse_ServerDefaultsToEnvVars() {
@@ -103,10 +105,74 @@ func (s ArgsTestSuite) Test_Parse_ServerDefaultsToEnvVars() {
 	for _, d := range data {
 		os.Setenv(d.key, d.expected)
 	}
+	defer func() {
+		for _, d := range data {
+			os.Unsetenv(d.key)
+		}
+	}()
+
 	args{}.parse()
 	for _, d := range data {
 		s.Equal(d.expected, *d.value)
 	}
+
+	s.Len(serverImpl.ListenerAddresses, 1)
+}
+
+func (s ArgsTestSuite) Test_Parse_ParsesListnerAddressShortArgs() {
+	dataTable := []struct {
+		value    []string
+		expected []string
+	}{
+		{[]string{"-l", "dfsl1", "-l", "dfsl2"}, []string{"dfsl1", "dfsl2"}},
+		{[]string{"-l", "dfsl1"}, []string{"dfsl1"}},
+	}
+
+	rootArgs := []string{"myProgram", "server"}
+	for _, data := range dataTable {
+		os.Args = append(rootArgs, data.value...)
+		args{}.parse()
+		s.Require().Equal(data.expected, serverImpl.ListenerAddresses)
+	}
+}
+
+func (s ArgsTestSuite) Test_Parse_ParsesListnerAddressLongArgs() {
+	dataTable := []struct {
+		value    []string
+		expected []string
+	}{
+		{[]string{"--listener-address", "dfsl1", "--listener-address", "dfsl2"}, []string{"dfsl1", "dfsl2"}},
+		{[]string{"--listener-address", "dfsl1"}, []string{"dfsl1"}},
+	}
+
+	rootArgs := []string{"myProgram", "server"}
+	for _, data := range dataTable {
+		os.Args = append(rootArgs, data.value...)
+		args{}.parse()
+		s.Require().Equal(data.expected, serverImpl.ListenerAddresses)
+	}
+}
+
+func (s ArgsTestSuite) Test_Parse_ParsesListnerAddressEnvVars() {
+	os.Args = []string{"myProgram", "server"}
+	dataTable := []struct {
+		value    string
+		expected []string
+	}{
+		{"dfsl1,dfsl2", []string{"dfsl1", "dfsl2"}},
+		{"dfsl1", []string{"dfsl1"}},
+	}
+
+	defer func() {
+		os.Unsetenv("LISTENER_ADDRESS")
+	}()
+
+	for _, data := range dataTable {
+		os.Setenv("LISTENER_ADDRESS", data.value)
+		args{}.parse()
+		s.Require().Equal(data.expected, serverImpl.ListenerAddresses)
+	}
+
 }
 
 // Suite

docs/config.md

@@ -31,9 +31,10 @@ The following environment variables can be used to configure the *Docker Flow Pr
 |EXTRA_FRONTEND     |Value will be added to the default `frontend` configuration. Multiple lines should be separated with comma (*,*).|
 |EXTRA_GLOBAL       |Value will be added to the default `global` configuration. Multiple lines should be separated with comma (*,*).|
 |HTTPS_ONLY         |If set to true, all requests to all services will be redirected to HTTPS.<br>**Example:** `true`<br>**Default Value:** `false`|
-|LISTENER_ADDRESS   |The address of the [Docker Flow: Swarm Listener](https://github.com/docker-flow/docker-flow-swarm-listener) used for automatic proxy configuration.<br>**Example:** `swarm-listener:8080`|
+|LISTENER_ADDRESS   |The address of the [Docker Flow: Swarm Listener](https://github.com/docker-flow/docker-flow-swarm-listener) used for automatic proxy configuration. Multiple values can be separated with comma (`,`). When set to multiple values, the proxy will query each address in order.<br>**Example:** `swarm-listener`|
 PROXY_INSTANCE_NAME|The name of the proxy instance. Useful if multiple proxies are running inside a cluster.<br>**Default value:** `docker-flow`|
 |RECONFIGURE_ATTEMPTS|The number of attempts the proxy will try to reconfigure itself before giving up and removing the offending service. The period between reconfigure attempts is 1 second.<br>**Example:** `15`<br>**Default value:** `20`|
+|RELOAD_ATTEMPTS    |The number of attempts the proxy will query a listener addresss during startup. Only used when LISTENER_ADDRESS is a comma seperated list of addresses.<br>**Default value:** `5`|
 |RELOAD_INTERVAL    |Defines the frequency (in milliseconds) between automatic config reloads from Swarm Listener.<br>**Default value:** `5000`|
 |REPEAT_RELOAD      |If set to `true`, the proxy will periodically reload the config, using `RELOAD_INTERVAL` as pause between iterations.<br>**Example:** `true`<br>**Default value:** `false`|
 |RESOLVERS          |The list of resolvers separated with comma (`,`). The `CHECK_RESOLVERS` environment variable must be set to `true`.<br>**Example:** `nameserver dns-0  4.4.2.1:53,nameserver dns-1  8.8.8.8:53`|

server.go

@@ -23,16 +23,18 @@ type Server interface {
 }
 
 type serve struct {
-	IP                   string `short:"i" long:"ip" default:"0.0.0.0" env:"IP" description:"IP the server listens to."`
-	ListenerAddress      string `short:"l" long:"listener-address" env:"LISTENER_ADDRESS" description:"The address of the Docker Flow: Swarm Listener. The address matches the name of the Swarm service (e.g. swarm-listener)"`
-	Port                 string `short:"p" long:"port" default:"8080" env:"PORT" description:"Port the server listens to."`
-	ServiceName          string `short:"n" long:"service-name" default:"proxy" env:"SERVICE_NAME" description:"The name of the proxy service. It is used only when running in 'swarm' mode and must match the '--name' parameter used to launch the service."`
+	IP                   string   `short:"i" long:"ip" default:"0.0.0.0" env:"IP" description:"IP the server listens to."`
+	ListenerAddresses    []string `short:"l" long:"listener-address" env:"LISTENER_ADDRESS" env-delim:"," description:"The address of the Docker Flow: Swarm Listener. The address matches the name of the Swarm service (e.g. swarm-listener)" default:""`
+	Port                 string   `short:"p" long:"port" default:"8080" env:"PORT" description:"Port the server listens to."`
+	ServiceName          string   `short:"n" long:"service-name" default:"proxy" env:"SERVICE_NAME" description:"The name of the proxy service. It is used only when running in 'swarm' mode and must match the '--name' parameter used to launch the service."`
 	SuccessfulInitReload bool
 	// TODO: Remove
 	actions.BaseReconfigure
 }
 
-var serverImpl = serve{}
+var serverImpl = serve{
+	ListenerAddresses: []string{},
+}
 var cert server.Certer = server.NewCert("/certs")
 
 // Execute runs the Web server.
@@ -46,7 +48,7 @@ func (m *serve) Execute(args []string) error {
 	address := fmt.Sprintf("%s:%s", m.IP, m.Port)
 	cert.Init()
 	var server2 = server.NewServer(
-		m.ListenerAddress,
+		m.ListenerAddresses,
 		m.Port,
 		m.ServiceName,
 		m.ConfigsPath,
@@ -77,12 +79,10 @@ func (m *serve) Execute(args []string) error {
 }
 
 func (m *serve) reconfigure(server server.Server) error {
-	lAddr := ""
-	if len(m.ListenerAddress) > 0 {
-		lAddr = fmt.Sprintf("http://%s:8080", m.ListenerAddress)
-	}
 	fetch := actions.NewFetch(m.BaseReconfigure)
-	if len(lAddr) > 0 {
+
+	if len(m.ListenerAddresses) == 1 && len(m.ListenerAddresses[0]) > 0 {
+		lAddr := fmt.Sprintf("http://%s:8080", m.ListenerAddresses[0])
 		go func() {
 			retryInterval := os.Getenv("RELOAD_INTERVAL")
 			interval, _ := time.ParseDuration(retryInterval + "ms")
@@ -105,6 +105,41 @@ func (m *serve) reconfigure(server server.Server) error {
 		}()
 	}
 
+	// Handlers Listener Addresses
+	if len(m.ListenerAddresses) > 1 {
+		reloadAttemptsStr := os.Getenv("RELOAD_ATTEMPTS")
+		retryInterval := os.Getenv("RELOAD_INTERVAL")
+		interval, _ := time.ParseDuration(retryInterval + "ms")
+		for _, addr := range m.ListenerAddresses {
+			if len(addr) == 0 {
+				continue
+			}
+			lAddr := fmt.Sprintf("http://%s:8080", addr)
+			go func(lAddr string) {
+				reloadAttempts, err := strconv.ParseInt(reloadAttemptsStr, 10, 64)
+				if err != nil {
+					reloadAttempts = 5
+				}
+				for range time.Tick(interval) {
+					if err := fetch.ReloadConfig(m.BaseReconfigure, lAddr); err != nil {
+						logPrintf(
+							"Error: Fetching config from swarm listener failed: %s. Will retry in %d seconds.",
+							err.Error(),
+							interval/time.Second,
+						)
+					} else {
+						m.SuccessfulInitReload = true
+						break
+					}
+					reloadAttempts = reloadAttempts - 1
+					if reloadAttempts <= 0 {
+						break
+					}
+				}
+			}(lAddr)
+		}
+	}
+
 	services := server.GetServicesFromEnvVars()
 
 	for _, service := range *services {

server/cert_test.go

@@ -1,11 +1,8 @@
 package server
 
 import (
-	"../proxy"
 	"encoding/json"
 	"fmt"
-	"github.com/stretchr/testify/mock"
-	"github.com/stretchr/testify/suite"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -14,6 +11,10 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"../proxy"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
 )
 
 type CertTestSuite struct {

server/server.go

@@ -30,23 +30,23 @@ const (
 )
 
 type serve struct {
-	listenerAddress string
-	port            string
-	serviceName     string
-	configsPath     string
-	templatesPath   string
-	cert            Certer
+	listenerAddresses []string
+	port              string
+	serviceName       string
+	configsPath       string
+	templatesPath     string
+	cert              Certer
 }
 
 // NewServer returns instance of the Server with populated data
-var NewServer = func(listenerAddr, port, serviceName, configsPath, templatesPath string, cert Certer) Server {
+var NewServer = func(listenerAddr []string, port, serviceName, configsPath, templatesPath string, cert Certer) Server {
 	return &serve{
-		listenerAddress: listenerAddr,
-		port:            port,
-		serviceName:     serviceName,
-		configsPath:     configsPath,
-		templatesPath:   templatesPath,
-		cert:            cert,
+		listenerAddresses: listenerAddr,
+		port:              port,
+		serviceName:       serviceName,
+		configsPath:       configsPath,
+		templatesPath:     templatesPath,
+		cert:              cert,
 	}
 }
 
@@ -143,22 +143,29 @@ func (m *serve) ReloadHandler(w http.ResponseWriter, req *http.Request) {
 	req.ParseForm()
 	params := new(reloadParams)
 	decoder.Decode(params, req.Form)
-	listenerAddr := ""
 	response := Response{
 		Status: "OK",
 	}
-	if params.FromListener {
-		listenerAddr = m.listenerAddress
-	}
+
 	//MW: I've reconstructed original behavior. BUT.
 	//shouldn't reload call ReloadServicesFromRegistry not just
 	//reload in else, if so ReloadClusterConfig & ReloadServicesFromRegistry
 	//could be enclosed in one method
-	if len(listenerAddr) > 0 {
-		fetch := actions.NewFetch(m.getBaseReconfigure())
-		if err := fetch.ReloadClusterConfig(listenerAddr); err != nil {
-			logPrintf("Error: ReloadClusterConfig failed: %s", err.Error())
-			m.writeInternalServerError(w, &Response{}, err.Error())
+	if params.FromListener {
+		errs := []string{}
+		for _, listenerAddr := range m.listenerAddresses {
+			if len(listenerAddr) == 0 {
+				continue
+			}
+			fetch := actions.NewFetch(m.getBaseReconfigure())
+			if err := fetch.ReloadClusterConfig(listenerAddr); err != nil {
+				errs = append(errs, err.Error())
+				logPrintf("Error: ReloadClusterConfig failed: %s", err.Error())
+			}
+		}
+		if len(errs) != 0 {
+			errMsg := strings.Join(errs, " ,")
+			m.writeInternalServerError(w, &Response{}, errMsg)
 		} else {
 			w.WriteHeader(http.StatusOK)
 		}