Add helper to verify if the configuration file changed

controllers/nginx-third-party/Dockerfile

@@ -12,7 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM gcr.io/google_containers/nginx-slim:0.3
+FROM gcr.io/google_containers/nginx-slim:0.4
+
+RUN apt-get update && apt-get install -y \
+  diffutils \
+  --no-install-recommends \
+  && rm -rf /var/lib/apt/lists/*
 
 COPY nginx-third-party-lb /
 COPY nginx.tmpl /

controllers/nginx-third-party/controller.go

@@ -28,11 +28,11 @@ import (
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	"k8s.io/kubernetes/pkg/client/cache"
-	"k8s.io/kubernetes/pkg/client/record"
 	client "k8s.io/kubernetes/pkg/client/unversioned"
 	"k8s.io/kubernetes/pkg/controller/framework"
 	"k8s.io/kubernetes/pkg/labels"
 	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/util/intstr"
 	"k8s.io/kubernetes/pkg/util/wait"
 	"k8s.io/kubernetes/pkg/watch"
 
@@ -76,7 +76,6 @@ type loadBalancerController struct {
 	svcLister        cache.StoreToServiceLister
 	configLister     StoreToConfigMapLister
 	endpLister       cache.StoreToEndpointsLister
-	recorder         record.EventRecorder
 	stopCh           chan struct{}
 	nginx            *nginx.NginxManager
 	lbInfo           *lbInfo
@@ -229,9 +228,7 @@ func (lbc *loadBalancerController) registerHandlers() {
 
 func (lbc *loadBalancerController) sync() {
 	ings := lbc.ingLister.Store.List()
-	upstreams, servers, update := lbc.updateNGINX(ings)
+	upstreams, servers := lbc.getUpstreamServers(ings)
-	if update {
-		glog.V(2).Infof("syncing NGINX config")
 
 	var kindAnnotations map[string]string
 	ngxCfgAnn, _ := annotations(kindAnnotations).getNginxConfig()
@@ -244,16 +241,15 @@ func (lbc *loadBalancerController) sync() {
 	tcpServices := getTCPServices(lbc.client, tcpSvcAnn)
 	lbc.nginx.CheckAndReload(ngxConfig, upstreams, servers, tcpServices)
 }
-}
 
-func (lbc *loadBalancerController) updateNGINX(data []interface{}) ([]nginx.Upstream, []nginx.Server, bool) {
+func (lbc *loadBalancerController) getUpstreamServers(data []interface{}) ([]nginx.Upstream, []nginx.Server) {
 	pems := make(map[string]string)
 
 	upstreams := make(map[string]nginx.Upstream)
-	var servers []nginx.Server
+	servers := make(map[string]nginx.Server)
 
 	for _, ingIf := range data {
-		ing := ingIf.(extensions.Ingress)
+		ing := ingIf.(*extensions.Ingress)
 
 		for _, rule := range ing.Spec.Rules {
 			if rule.IngressRuleValue.HTTP == nil {
@@ -261,47 +257,53 @@ func (lbc *loadBalancerController) updateNGINX(data []interface{}) ([]nginx.Upst
 			}
 
 			for _, path := range rule.HTTP.Paths {
-				name := ing.Namespace + "-" + path.Backend.ServiceName
+				name := ing.GetNamespace() + "-" + path.Backend.ServiceName
 
 				var ups nginx.Upstream
 
 				if existent, ok := upstreams[name]; ok {
 					ups = existent
 				} else {
-					ups := nginx.NewUpstreamWithDefaultServer(name)
+					ups = nginx.NewUpstream(name)
-					upstreams[name] = ups
 				}
 
-				svcKey := ing.Namespace + "/" + path.Backend.ServiceName
+				svcKey := ing.GetNamespace() + "/" + path.Backend.ServiceName
 				svcObj, svcExists, err := lbc.svcLister.Store.GetByKey(svcKey)
 				if err != nil {
 					glog.Infof("error getting service %v from the cache: %v", svcKey, err)
-				} else {
+					continue
-					if svcExists {
+				}
+
+				if !svcExists {
+					glog.Warningf("service %v does no exists", svcKey)
+					continue
+				}
+
 				svc := svcObj.(*api.Service)
-						if svc.Spec.ClusterIP != "None" && svc.Spec.ClusterIP != "" {
+
-							upsServer := nginx.UpstreamServer{Address: svc.Spec.ClusterIP, Port: path.Backend.ServicePort.String()}
+				for _, servicePort := range svc.Spec.Ports {
-							ups.Backends = []nginx.UpstreamServer{upsServer}
+					if servicePort.Port == path.Backend.ServicePort.IntValue() {
-						} else if svc.Spec.ClusterIP == "None" {
+						endps := lbc.getEndpoints(svc, servicePort.TargetPort)
-							endps, err := lbc.endpLister.GetServiceEndpoints(svc)
+						if len(endps) == 0 {
-							if err != nil {
+							glog.Warningf("service %v does no have any active endpoints", svcKey)
-								glog.Infof("error getting endpoints for service %v from the cache: %v", svc, err)
-							} else {
-								upsServers := endpointsToUpstreamServers(endps, path.Backend.ServicePort.IntValue())
-								if len(upsServers) > 0 {
-									ups.Backends = upsServers
-								}
-							}
 						}
+
+						ups.Backends = append(ups.Backends, endps...)
+						break
 					}
 				}
 
-				//upstreams[name] = append(upstreams[name], ups)
+				upstreams[name] = ups
 			}
 		}
 
 		for _, rule := range ing.Spec.Rules {
-			server := nginx.Server{Name: rule.Host}
+			var server nginx.Server
+			if existent, ok := servers[rule.Host]; ok {
+				server = existent
+			} else {
+				server = nginx.Server{Name: rule.Host}
+			}
 
 			if pemFile, ok := pems[rule.Host]; ok {
 				server.SSL = true
@@ -313,7 +315,7 @@ func (lbc *loadBalancerController) updateNGINX(data []interface{}) ([]nginx.Upst
 
 			for _, path := range rule.HTTP.Paths {
 				loc := nginx.Location{Path: path.Path}
-				upsName := ing.GetName() + "-" + path.Backend.ServiceName
+				upsName := ing.GetNamespace() + "-" + path.Backend.ServiceName
 
 				for _, ups := range upstreams {
 					if upsName == ups.Name {
@@ -323,33 +325,63 @@ func (lbc *loadBalancerController) updateNGINX(data []interface{}) ([]nginx.Upst
 				locations = append(locations, loc)
 			}
 
-			server.Locations = locations
+			server.Locations = append(server.Locations, locations...)
-			servers = append(servers, server)
+			servers[rule.Host] = server
 		}
 	}
 
-	uValues := make([]nginx.Upstream, 0, len(upstreams))
+	aUpstreams := make([]nginx.Upstream, 0, len(upstreams))
 	for _, value := range upstreams {
+		if len(value.Backends) == 0 {
+			value.Backends = append(value.Backends, nginx.NewDefaultServer())
+		}
 		sort.Sort(nginx.UpstreamServerByAddrPort(value.Backends))
-		uValues = append(uValues, value)
+		aUpstreams = append(aUpstreams, value)
 	}
-	sort.Sort(nginx.UpstreamByNameServers(uValues))
+	sort.Sort(nginx.UpstreamByNameServers(aUpstreams))
 
-	sort.Sort(nginx.ServerByNamePort(servers))
+	aServers := make([]nginx.Server, 0, len(servers))
+	for _, value := range servers {
+		sort.Sort(nginx.LocationByPath(value.Locations))
+		aServers = append(aServers, value)
+	}
+	sort.Sort(nginx.ServerByName(aServers))
 
-	return uValues, servers, true
+	return aUpstreams, aServers
+}
+
+// getEndpoints returns a list of <endpoint ip>:<port> for a given service/target port combination.
+func (lbc *loadBalancerController) getEndpoints(s *api.Service, servicePort intstr.IntOrString) []nginx.UpstreamServer {
+	ep, err := lbc.endpLister.GetServiceEndpoints(s)
+	if err != nil {
+		glog.Warningf("unexpected error obtaining service endpoints: %v", err)
+		return []nginx.UpstreamServer{}
 	}
 
-func endpointsToUpstreamServers(endps api.Endpoints, servicePort int) []nginx.UpstreamServer {
 	var upsServers []nginx.UpstreamServer
-	for _, subset := range endps.Subsets {
+
-		for _, port := range subset.Ports {
+	for _, ss := range ep.Subsets {
-			if port.Port == servicePort {
+		for _, epPort := range ss.Ports {
-				for _, address := range subset.Addresses {
+			var targetPort int
-					ups := nginx.UpstreamServer{Address: address.IP, Port: fmt.Sprintf("%v", servicePort)}
+
-					upsServers = append(upsServers, ups)
+			switch servicePort.Type {
+			case intstr.Int:
+				if epPort.Port == servicePort.IntValue() {
+					targetPort = epPort.Port
 				}
-				break
+			case intstr.String:
+				if epPort.Name == servicePort.StrVal {
+					targetPort = epPort.Port
+				}
+			}
+
+			if targetPort == 0 {
+				continue
+			}
+
+			for _, epAddress := range ss.Addresses {
+				ups := nginx.UpstreamServer{Address: epAddress.IP, Port: fmt.Sprintf("%v", targetPort)}
+				upsServers = append(upsServers, ups)
 			}
 		}
 	}
@@ -366,23 +398,27 @@ func (lbc *loadBalancerController) Stop() {
 	// Only try draining the workqueue if we haven't already.
 	if !lbc.shutdown {
 		close(lbc.stopCh)
-		glog.Infof("Shutting down controller queues")
+		glog.Infof("shutting down controller queues")
 		lbc.shutdown = true
 	}
 }
 
 // Run starts the loadbalancer controller.
 func (lbc *loadBalancerController) Run() {
-	glog.Infof("Starting NGINX loadbalancer controller")
+	glog.Infof("starting NGINX loadbalancer controller")
 	go lbc.nginx.Start()
 	go lbc.registerHandlers()
 
 	go lbc.configController.Run(lbc.stopCh)
 	go lbc.ingController.Run(lbc.stopCh)
+	go lbc.endpController.Run(lbc.stopCh)
+	go lbc.svcController.Run(lbc.stopCh)
 
 	// periodic check for changes in configuration
 	go wait.Until(lbc.sync, 5*time.Second, wait.NeverStop)
 
+	time.Sleep(5 * time.Second)
+
 	<-lbc.stopCh
-	glog.Infof("Shutting down NGINX loadbalancer controller")
+	glog.Infof("shutting down NGINX loadbalancer controller")
 }

controllers/nginx-third-party/nginx.tmpl

@@ -1,9 +1,3 @@
-{{range $name, $upstream := .upstreams}}
-upstream {{$upstream.Name}} {
-  {{range $server := $upstream.UpstreamServers}}
-  server {{$server.Address}}:{{$server.Port}};{{end}}
-}{{end}}
-
 {{ $cfg := .cfg }}{{ $sslCertificates := .sslCertificates }}{{ $defErrorSvc := .defErrorSvc }}{{ $defBackend := .defBackend }}
 daemon off;
 
@@ -133,14 +127,13 @@ http {
     {{ end }}
 
     {{ if $defErrorSvc }}
-    # Custom error pages using
+    # Custom error pages
     proxy_intercept_errors on;
     error_page 403 @custom_403;
     error_page 404 @custom_404;
     error_page 405 @custom_405;
     error_page 408 @custom_408;
     error_page 413 @custom_413;
-    error_page 500 @custom_500;
     error_page 501 @custom_501;
     error_page 502 @custom_502;
     error_page 503 @custom_503;
@@ -179,12 +172,7 @@ http {
         #vhost_traffic_status_filter_by_host on;
 
         location / {
-            set $upstream_host '';
+            return 200;
-            set $upstream_port '';
-            access_by_lua_block {
-                require("ingress").content(ngx)
-            }
-            proxy_pass http://$upstream_host:$upstream_port$request_uri;
         }
 
         {{ if $defErrorSvc }}{{ template "CUSTOM_ERRORS" (dict "cfg" $cfg "defErrorSvc" $defErrorSvc) }}{{ end }}
@@ -195,7 +183,6 @@ http {
     # TODO: support more than one certificate
     server {
         listen 443 ssl http2 default_server;
-
         {{ range $sslCert := .sslCertificates }}{{ if $sslCert.Default }}
         # default certificate in case no match
         ssl_certificate "{{ $sslCert.Cert }}";
@@ -210,29 +197,38 @@ http {
     }
     {{ end }}
 
+    {{range $name, $upstream := .upstreams}}
+    upstream {{$upstream.Name}} {
+        least_conn;
+        {{range $server := $upstream.Backends}}server {{$server.Address}}:{{$server.Port}};
+        {{end}}
+    }
+    {{end}}
+
     {{ range $server := .servers }}
     server {
         listen 80;
-      {{ if $server.SSL }}
+        {{ if $server.SSL }}listen 443 ssl http2;
-      listen 443 ssl http2;
         ssl_certificate {{ $server.SSLCertificate }};
-      ssl_certificate_key {{ $server.SSLCertificateKey }};
+        ssl_certificate_key {{ $server.SSLCertificateKey }};{{ end }}
-      {{ end }}
 
         server_name {{ $server.Name }};
-
         {{ if $server.SSL }}
         if ($scheme = http) {
             return 301 https://$host$request_uri;
         }
         {{ end }}
-
         {{ range $location := $server.Locations }}
         location {{ $location.Path }} {
             proxy_set_header Host $host;
             proxy_pass http://{{ $location.Upstream.Name }};
-      }{{ end }}
+        }
-    }{{ end }}
+        {{ end }}
+
+        {{ if $defErrorSvc }}{{ template "CUSTOM_ERRORS" (dict "cfg" $cfg "defErrorSvc" $defErrorSvc) }}{{ end }}
+
+    }
+    {{ end }}
 
     # default server, including healthcheck
     server {
@@ -244,20 +240,6 @@ http {
             return 200;
         }
        
-        # route to get the current Ingress configuration used in ingress.lua
-        location /config {
-            content_by_lua_block {
-                require("ingress").config(ngx)
-            }
-        }
-
-        # route to post the list of Ingress rules to use.
-        location /update-ingress {
-            content_by_lua_block {
-                require("ingress").update_ingress(ngx)
-            }
-        }
-        
         location /health-check {
             access_log off;
             proxy_pass http://127.0.0.1:10249/healthz;
@@ -320,12 +302,6 @@ stream {
             }
         }
 
-        location @custom_500 {
-            content_by_lua_block {
-                openURL(500, dev_error_url)
-            }
-        }
-
         location @custom_501 {
             content_by_lua_block {
                 openURL(501, dev_error_url)

controllers/nginx-third-party/nginx/command.go

@@ -30,7 +30,7 @@ const (
 // Start starts a nginx (master process) and waits. If the process ends
 // we need to kill the controller process and return the reason.
 func (ngx *NginxManager) Start() {
-	glog.Info("Starting nginx...")
+	glog.Info("Starting NGINX process...")
 	cmd := exec.Command("nginx")
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
@@ -43,7 +43,9 @@ func (ngx *NginxManager) Start() {
 	}
 }
 
-// Reload the master process receives the signal to reload configuration, it checks
+// CheckAndReload verify if the nginx configuration changed and sends a reload
+//
+// the master process receives the signal to reload configuration, it checks
 // the syntax validity of the new configuration file and tries to apply the
 // configuration provided in it. If this is a success, the master process starts
 // new worker processes and sends messages to old worker processes, requesting them
@@ -58,13 +60,13 @@ func (ngx *NginxManager) CheckAndReload(cfg *nginxConfiguration, upstreams []Ups
 
 	newCfg, err := ngx.writeCfg(cfg, upstreams, servers, servicesL4)
 	if err != nil {
-		glog.Errorf("Failed to write new nginx configuration. Avoiding reload: %v", err)
+		glog.Errorf("failed to write new nginx configuration. Avoiding reload: %v", err)
 		return
 	}
 
 	if newCfg {
 		if err := ngx.shellOut("nginx -s reload"); err == nil {
-			glog.Info("Change in configuration detected. Reloading...")
+			glog.Info("change in configuration detected. Reloading...")
 		}
 	}
 }
@@ -74,7 +76,7 @@ func (ngx *NginxManager) CheckAndReload(cfg *nginxConfiguration, upstreams []Ups
 func (ngx *NginxManager) shellOut(cmd string) error {
 	out, err := exec.Command("sh", "-c", cmd).CombinedOutput()
 	if err != nil {
-		glog.Errorf("Failed to execute %v: %v", cmd, string(out))
+		glog.Errorf("failed to execute %v: %v", cmd, string(out))
 		return err
 	}
 

controllers/nginx-third-party/nginx/main.go

@@ -23,6 +23,8 @@ import (
 	"sync"
 	"text/template"
 
+	"github.com/golang/glog"
+
 	"k8s.io/contrib/ingress/controllers/nginx-third-party/ssl"
 
 	"k8s.io/kubernetes/pkg/client/record"
@@ -237,7 +239,7 @@ type NginxManager struct {
 // defaultConfiguration returns the default configuration contained
 // in the file default-conf.json
 func newDefaultNginxCfg() *nginxConfiguration {
-	return &nginxConfiguration{
+	cfg := nginxConfiguration{
 		BodySize:                 bodySize,
 		ErrorLogLevel:            errorLevel,
 		UseHTS:                   true,
@@ -263,6 +265,12 @@ func newDefaultNginxCfg() *nginxConfiguration {
 		UseGzip:                  true,
 		WorkerProcesses:          strconv.Itoa(runtime.NumCPU()),
 	}
+
+	if glog.V(5) {
+		cfg.ErrorLogLevel = "debug"
+	}
+
+	return &cfg
 }
 
 // NewManager ...

controllers/nginx-third-party/nginx/nginx.go

@@ -1,3 +1,19 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 package nginx
 
 // NGINXController Updates NGINX configuration, starts and reloads NGINX
@@ -20,6 +36,7 @@ type Upstream struct {
 	Backends []UpstreamServer
 }
 
+// UpstreamByNameServers Upstream sorter by name
 type UpstreamByNameServers []Upstream
 
 func (c UpstreamByNameServers) Len() int      { return len(c) }
@@ -34,6 +51,7 @@ type UpstreamServer struct {
 	Port    string
 }
 
+// UpstreamServerByAddrPort UpstreamServer sorter by address and port
 type UpstreamServerByAddrPort []UpstreamServer
 
 func (c UpstreamServerByAddrPort) Len() int      { return len(c) }
@@ -59,11 +77,12 @@ type Server struct {
 	SSLCertificateKey string
 }
 
-type ServerByNamePort []Server
+// ServerByName Server sorter by name
+type ServerByName []Server
 
-func (c ServerByNamePort) Len() int      { return len(c) }
+func (c ServerByName) Len() int      { return len(c) }
-func (c ServerByNamePort) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
+func (c ServerByName) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
-func (c ServerByNamePort) Less(i, j int) bool {
+func (c ServerByName) Less(i, j int) bool {
 	return c[i].Name < c[j].Name
 }
 
@@ -73,20 +92,24 @@ type Location struct {
 	Upstream Upstream
 }
 
-type locByPathUpstream []Location
+// LocationByPath Location sorter by path
+type LocationByPath []Location
 
-func (c locByPathUpstream) Len() int      { return len(c) }
+func (c LocationByPath) Len() int      { return len(c) }
-func (c locByPathUpstream) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
+func (c LocationByPath) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
-func (c locByPathUpstream) Less(i, j int) bool {
+func (c LocationByPath) Less(i, j int) bool {
 	return c[i].Path < c[j].Path
 }
 
-// NewUpstreamWithDefaultServer creates an upstream with the default server.
+// NewDefaultServer return an UpstreamServer to be use as default server returns 502.
-// proxy_pass to an upstream with the default server returns 502.
+func NewDefaultServer() UpstreamServer {
-// We use it for services that have no endpoints
+	return UpstreamServer{Address: "127.0.0.1", Port: "8181"}
-func NewUpstreamWithDefaultServer(name string) Upstream {
+}
+
+// NewUpstream creates an upstream without servers.
+func NewUpstream(name string) Upstream {
 	return Upstream{
 		Name:     name,
-		Backends: []UpstreamServer{UpstreamServer{Address: "127.0.0.1", Port: "8181"}},
+		Backends: []UpstreamServer{},
 	}
 }

controllers/nginx-third-party/nginx/template.go

@@ -17,10 +17,10 @@ limitations under the License.
 package nginx
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"os"
 	"text/template"
 
 	"github.com/fatih/structs"
@@ -61,11 +61,6 @@ func (ngx *NginxManager) loadTemplate() {
 }
 
 func (ngx *NginxManager) writeCfg(cfg *nginxConfiguration, upstreams []Upstream, servers []Server, servicesL4 []Service) (bool, error) {
-	file, err := os.Create(ngx.ConfigFile)
-	if err != nil {
-		return false, err
-	}
-
 	fromMap := structs.Map(cfg)
 	toMap := structs.Map(ngx.defCfg)
 	curNginxCfg := merge(toMap, fromMap)
@@ -86,7 +81,18 @@ func (ngx *NginxManager) writeCfg(cfg *nginxConfiguration, upstreams []Upstream,
 		conf["defErrorSvc"] = false
 	}
 
-	if glog.V(2) {
+	buffer := new(bytes.Buffer)
+	err := ngx.template.Execute(buffer, conf)
+	if err != nil {
+		return false, err
+	}
+
+	changed, err := checkChanges(ngx.ConfigFile, buffer)
+	if err != nil {
+		return false, err
+	}
+
+	if glog.V(3) {
 		b, err := json.Marshal(conf)
 		if err != nil {
 			fmt.Println("error:", err)
@@ -94,10 +100,5 @@ func (ngx *NginxManager) writeCfg(cfg *nginxConfiguration, upstreams []Upstream,
 		glog.Infof("nginx configuration: %v", string(b))
 	}
 
-	err = ngx.template.Execute(file, conf)
+	return changed, nil
-	if err != nil {
-		return false, err
-	}
-
-	return true, nil
 }

controllers/nginx-third-party/nginx/utils.go

@@ -17,10 +17,13 @@ limitations under the License.
 package nginx
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"os"
+	"os/exec"
 	"reflect"
 	"strings"
 
@@ -36,7 +39,7 @@ func (ngx *NginxManager) IsHealthy() error {
 	defer res.Body.Close()
 
 	if res.StatusCode != 200 {
-		return fmt.Errorf("nginx status is unhealthy")
+		return fmt.Errorf("NGINX is unhealthy")
 	}
 
 	return nil
@@ -67,7 +70,7 @@ func getDnsServers() []string {
 		}
 	}
 
-	glog.V(2).Infof("Nameservers to use: %v", nameservers)
+	glog.V(3).Infof("nameservers to use: %v", nameservers)
 	return nameservers
 }
 
@@ -81,8 +84,8 @@ func (ngx *NginxManager) ReadConfig(data string) (*nginxConfiguration, error) {
 	cfg := nginxConfiguration{}
 	err := json.Unmarshal([]byte(data), &cfg)
 	if err != nil {
-		glog.Errorf("Invalid json: %v", err)
+		glog.Errorf("invalid json: %v", err)
-		return newDefaultNginxCfg(), fmt.Errorf("Invalid custom nginx configuration: %v", err)
+		return newDefaultNginxCfg(), fmt.Errorf("invalid custom nginx configuration: %v", err)
 	}
 
 	return &cfg, nil
@@ -116,3 +119,63 @@ func toMap(iface interface{}) (map[string]interface{}, bool) {
 
 	return map[string]interface{}{}, false
 }
+
+func checkChanges(filename string, data *bytes.Buffer) (bool, error) {
+	in, err := os.Open(filename)
+	if err != nil {
+		return false, err
+	}
+
+	src, err := ioutil.ReadAll(in)
+	in.Close()
+	if err != nil {
+		return false, err
+	}
+
+	res := data.Bytes()
+	if !bytes.Equal(src, res) {
+		err = ioutil.WriteFile(filename, res, 0644)
+		if err != nil {
+			return false, err
+		}
+
+		dData, err := diff(src, res)
+		if err != nil {
+			return false, fmt.Errorf("computing diff: %s", err)
+		}
+
+		if glog.V(2) {
+			glog.Infof("NGINX configuration diff a/%s b/%s\n", filename, filename)
+			glog.Infof("%v", string(dData))
+		}
+
+		return len(dData) > 0, nil
+	}
+
+	return false, nil
+}
+
+func diff(b1, b2 []byte) (data []byte, err error) {
+	f1, err := ioutil.TempFile("", "")
+	if err != nil {
+		return
+	}
+	defer os.Remove(f1.Name())
+	defer f1.Close()
+
+	f2, err := ioutil.TempFile("", "")
+	if err != nil {
+		return
+	}
+	defer os.Remove(f2.Name())
+	defer f2.Close()
+
+	f1.Write(b1)
+	f2.Write(b2)
+
+	data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).CombinedOutput()
+	if len(data) > 0 {
+		err = nil
+	}
+	return
+}