refactor: applies linting.

.golangci.toml

@@ -3,6 +3,21 @@
 
   skip-files = [
     "^old/.*",
+    "^acme/.*",
+    "^cluster/.*",
+    "^cmd/convert/.*",
+    "^h2c/.*",
+    "^integration/.*",
+
+#    "^cmd/traefik/.*",
+#    "^anonymize/.*",
+#    "^provider/.*",
+#    "^tracing/.*",
+#    "^safe/.*",
+#    "^h2c/.*",
+#    "^healthcheck/.*",
+#    "^middlewares/.*",
+#    "^server/.*",
   ]
 
 [linters-settings]
@@ -21,7 +36,7 @@
 
   [linters-settings.goconst]
     min-len = 3.0
-    min-occurrences = 3.0
+    min-occurrences = 4.0
 
   [linters-settings.misspell]
     locale = "US"
@@ -34,12 +49,18 @@
     "gas",
     "dupl",
     "prealloc",
+    "gochecknoinits",
+    "gochecknoglobals",
+    "unparam",
+    "scopelint",
+    "goimports",
   ]
 
 [issues]
   max-per-linter = 0
   max-same = 0
   exclude = [
+    "field `(foo|fuu)` is unused",
     "(.+) is deprecated:",
     "cyclomatic complexity (\\d+) of func `\\(\\*Builder\\)\\.buildConstructor` is high", #alt/server/middleware/middlewares.go
     "`logger` can be `github.com/containous/traefik/vendor/github.com/stretchr/testify/assert.TestingT`", # alt/middlewares/recovery/recovery.go:

cmd/bug/bug.go

@@ -155,15 +155,15 @@ func sendReport(body string) {
 	}
 }
 
-func openBrowser(URL string) error {
+func openBrowser(u string) error {
 	var err error
 	switch runtime.GOOS {
 	case "linux":
-		err = exec.Command("xdg-open", URL).Start()
+		err = exec.Command("xdg-open", u).Start()
 	case "windows":
-		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", URL).Start()
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", u).Start()
 	case "darwin":
-		err = exec.Command("open", URL).Start()
+		err = exec.Command("open", u).Start()
 	default:
 		err = fmt.Errorf("unsupported platform")
 	}

cmd/traefik/traefik.go

@@ -293,7 +293,7 @@ func runCmd(staticConfiguration *static.Configuration, configFile string) error
 		log.WithoutContext().Errorf("Could not enable Watchdog: %v", err)
 	} else if t != 0 {
 		// Send a ping each half time given
-		t = t / 2
+		t /= 2
 		log.WithoutContext().Infof("Watchdog activated with timer duration %s", t)
 		safe.Go(func() {
 			tick := time.Tick(t)

config/static/entrypoints.go

@@ -116,7 +116,9 @@ func makeEntryPointTLS(result map[string]string) (*tls.TLS, error) {
 	if configTLS != nil {
 		if len(result["ca"]) > 0 {
 			files := tls.FilesOrContents{}
-			files.Set(result["ca"])
+			if err := files.Set(result["ca"]); err != nil {
+				return nil, err
+			}
 			optional := toBool(result, "ca_optional")
 			configTLS.ClientCA = tls.ClientCA{
 				Files:    files,

config/static/static_config.go

@@ -334,12 +334,10 @@ func (c *Configuration) ValidateConfiguration() {
 	if c.ACME != nil {
 		if _, ok := c.EntryPoints[c.ACME.EntryPoint]; !ok {
 			log.Fatalf("Unknown entrypoint %q for ACME configuration", c.ACME.EntryPoint)
-		} else {
+		} else if c.EntryPoints[c.ACME.EntryPoint].TLS == nil {
-			if c.EntryPoints[c.ACME.EntryPoint].TLS == nil {
 			log.Fatalf("Entrypoint %q has no TLS configuration for ACME configuration", c.ACME.EntryPoint)
 		}
 	}
-	}
 }
 
 func getSafeACMECAServer(caServerSrc string) string {

healthcheck/healthcheck.go

@@ -132,35 +132,35 @@ func (hc *HealthCheck) checkBackend(backend *BackendConfig) {
 	var newDisabledURLs []*url.URL
 	// FIXME re enable metrics
 	for _, disableURL := range backend.disabledURLs {
-		//serverUpMetricValue := float64(0)
+		// FIXME serverUpMetricValue := float64(0)
 		if err := checkHealth(disableURL, backend); err == nil {
 			log.Warnf("Health check up: Returning to server list. Backend: %q URL: %q", backend.name, disableURL.String())
-			if err := backend.LB.UpsertServer(disableURL, roundrobin.Weight(1)); err != nil {
+			if err = backend.LB.UpsertServer(disableURL, roundrobin.Weight(1)); err != nil {
 				log.Error(err)
 			}
-			//serverUpMetricValue = 1
+			// FIXME serverUpMetricValue = 1
 		} else {
 			log.Warnf("Health check still failing. Backend: %q URL: %q Reason: %s", backend.name, disableURL.String(), err)
 			newDisabledURLs = append(newDisabledURLs, disableURL)
 		}
-		//labelValues := []string{"backend", backend.name, "url", disableURL.String()}
+		// FIXME labelValues := []string{"backend", backend.name, "url", disableURL.String()}
-		//hc.metrics.BackendServerUpGauge().With(labelValues...).Set(serverUpMetricValue)
+		// FIXME hc.metrics.BackendServerUpGauge().With(labelValues...).Set(serverUpMetricValue)
 	}
 	backend.disabledURLs = newDisabledURLs
 
 	// FIXME re enable metrics
 	for _, enableURL := range enabledURLs {
-		//serverUpMetricValue := float64(1)
+		// FIXME serverUpMetricValue := float64(1)
 		if err := checkHealth(enableURL, backend); err != nil {
 			log.Warnf("Health check failed: Remove from server list. Backend: %q URL: %q Reason: %s", backend.name, enableURL.String(), err)
 			if err := backend.LB.RemoveServer(enableURL); err != nil {
 				log.Error(err)
 			}
 			backend.disabledURLs = append(backend.disabledURLs, enableURL)
-			//serverUpMetricValue = 0
+			// FIXME serverUpMetricValue = 0
 		}
-		//labelValues := []string{"backend", backend.name, "url", enableURL.String()}
+		// FIXME labelValues := []string{"backend", backend.name, "url", enableURL.String()}
-		//hc.metrics.BackendServerUpGauge().With(labelValues...).Set(serverUpMetricValue)
+		// FIXME hc.metrics.BackendServerUpGauge().With(labelValues...).Set(serverUpMetricValue)
 	}
 }
 

middlewares/accesslog/logger.go

@@ -272,7 +272,7 @@ func (h *Handler) logTheRoundTrip(logDataTable *LogData, crr *captureRequestRead
 		core[DownstreamContentSize] = crw.Size()
 		if original, ok := core[OriginContentSize]; ok {
 			o64 := original.(int64)
-			if o64 != crw.Size() && 0 != crw.Size() {
+			if crw.Size() != o64 && crw.Size() != 0 {
 				core[GzipRatio] = float64(o64) / float64(crw.Size())
 			}
 		}

middlewares/auth/forward.go

@@ -167,19 +167,23 @@ func writeHeader(req *http.Request, forwardReq *http.Request, trustForwardHeader
 		forwardReq.Header.Set(forward.XForwardedFor, clientIP)
 	}
 
-	if xMethod := req.Header.Get(xForwardedMethod); xMethod != "" && trustForwardHeader {
+	xMethod := req.Header.Get(xForwardedMethod)
+	switch {
+	case xMethod != "" && trustForwardHeader:
 		forwardReq.Header.Set(xForwardedMethod, xMethod)
-	} else if req.Method != "" {
+	case req.Method != "":
 		forwardReq.Header.Set(xForwardedMethod, req.Method)
-	} else {
+	default:
 		forwardReq.Header.Del(xForwardedMethod)
 	}
 
-	if xfp := req.Header.Get(forward.XForwardedProto); xfp != "" && trustForwardHeader {
+	xfp := req.Header.Get(forward.XForwardedProto)
+	switch {
+	case xfp != "" && trustForwardHeader:
 		forwardReq.Header.Set(forward.XForwardedProto, xfp)
-	} else if req.TLS != nil {
+	case req.TLS != nil:
 		forwardReq.Header.Set(forward.XForwardedProto, "https")
-	} else {
+	default:
 		forwardReq.Header.Set(forward.XForwardedProto, "http")
 	}
 
@@ -187,19 +191,23 @@ func writeHeader(req *http.Request, forwardReq *http.Request, trustForwardHeader
 		forwardReq.Header.Set(forward.XForwardedPort, xfp)
 	}
 
-	if xfh := req.Header.Get(forward.XForwardedHost); xfh != "" && trustForwardHeader {
+	xfh := req.Header.Get(forward.XForwardedHost)
+	switch {
+	case xfh != "" && trustForwardHeader:
 		forwardReq.Header.Set(forward.XForwardedHost, xfh)
-	} else if req.Host != "" {
+	case req.Host != "":
 		forwardReq.Header.Set(forward.XForwardedHost, req.Host)
-	} else {
+	default:
 		forwardReq.Header.Del(forward.XForwardedHost)
 	}
 
-	if xfURI := req.Header.Get(xForwardedURI); xfURI != "" && trustForwardHeader {
+	xfURI := req.Header.Get(xForwardedURI)
+	switch {
+	case xfURI != "" && trustForwardHeader:
 		forwardReq.Header.Set(xForwardedURI, xfURI)
-	} else if req.URL.RequestURI() != "" {
+	case req.URL.RequestURI() != "":
 		forwardReq.Header.Set(xForwardedURI, req.URL.RequestURI())
-	} else {
+	default:
 		forwardReq.Header.Del(xForwardedURI)
 	}
 }

middlewares/headers/headers_test.go

@@ -106,7 +106,7 @@ func TestSecureHeader(t *testing.T) {
 
 func TestSSLForceHost(t *testing.T) {
 	next := http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		rw.Write([]byte("OK"))
+		_, _ = rw.Write([]byte("OK"))
 	})
 
 	testCases := []struct {

middlewares/passtlsclientcert/pass_tls_client_cert.go

@@ -271,7 +271,8 @@ func getSANs(cert *x509.Certificate) []string {
 		return sans
 	}
 
-	sans = append(cert.DNSNames, cert.EmailAddresses...)
+	sans = append(sans, cert.DNSNames...)
+	sans = append(sans, cert.EmailAddresses...)
 
 	var ips []string
 	for _, ip := range cert.IPAddresses {

middlewares/retry/retry_test.go

@@ -256,7 +256,7 @@ func TestRetryWebsocket(t *testing.T) {
 
 	forwarder, err := forward.New()
 	if err != nil {
-		t.Fatalf("Error creating forwarder: %s", err)
+		t.Fatalf("Error creating forwarder: %v", err)
 	}
 
 	backendServer := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
@@ -274,7 +274,7 @@ func TestRetryWebsocket(t *testing.T) {
 
 			loadBalancer, err := roundrobin.New(forwarder)
 			if err != nil {
-				t.Fatalf("Error creating load balancer: %s", err)
+				t.Fatalf("Error creating load balancer: %v", err)
 			}
 
 			basePort := 33444
@@ -287,7 +287,10 @@ func TestRetryWebsocket(t *testing.T) {
 			}
 
 			// add the functioning server to the end of the load balancer list
-			loadBalancer.UpsertServer(testhelpers.MustParseURL(backendServer.URL))
+			err = loadBalancer.UpsertServer(testhelpers.MustParseURL(backendServer.URL))
+			if err != nil {
+				t.Fatalf("Fail to upsert server: %v", err)
+			}
 
 			retryListener := &countingRetryListener{}
 			retryH, err := New(context.Background(), loadBalancer, config.Retry{Attempts: test.maxRequestAttempts}, retryListener, "traefikTest")

provider/acme/local_store.go

@@ -205,9 +205,7 @@ func (s *LocalStore) RemoveHTTPChallengeToken(token, domain string) error {
 	}
 
 	if _, ok := s.storedData.HTTPChallenges[token]; ok {
-		if _, domainOk := s.storedData.HTTPChallenges[token][domain]; domainOk {
 		delete(s.storedData.HTTPChallenges[token], domain)
-		}
 		if len(s.storedData.HTTPChallenges[token]) == 0 {
 			delete(s.storedData.HTTPChallenges, token)
 		}

provider/acme/provider.go

@@ -277,7 +277,8 @@ func (p *Provider) getClient() (*lego.Client, error) {
 		return nil, err
 	}
 
-	if p.DNSChallenge != nil && len(p.DNSChallenge.Provider) > 0 {
+	switch {
+	case p.DNSChallenge != nil && len(p.DNSChallenge.Provider) > 0:
 		logger.Debugf("Using DNS Challenge provider: %s", p.DNSChallenge.Provider)
 
 		var provider challenge.Provider
@@ -310,21 +311,23 @@ func (p *Provider) getClient() (*lego.Client, error) {
 			p.DNSChallenge.preCheckTimeout, p.DNSChallenge.preCheckInterval = challengeProviderTimeout.Timeout()
 		}
 
-	} else if p.HTTPChallenge != nil && len(p.HTTPChallenge.EntryPoint) > 0 {
+	case p.HTTPChallenge != nil && len(p.HTTPChallenge.EntryPoint) > 0:
 		logger.Debug("Using HTTP Challenge provider.")
 
 		err = client.Challenge.SetHTTP01Provider(&challengeHTTP{Store: p.Store})
 		if err != nil {
 			return nil, err
 		}
-	} else if p.TLSChallenge != nil {
+
+	case p.TLSChallenge != nil:
 		logger.Debug("Using TLS Challenge provider.")
 
 		err = client.Challenge.SetTLSALPN01Provider(&challengeTLSALPN{Store: p.Store})
 		if err != nil {
 			return nil, err
 		}
-	} else {
+
+	default:
 		return nil, errors.New("ACME challenge not specified, please select TLS or HTTP or DNS Challenge")
 	}
 

provider/base_provider.go

@@ -2,13 +2,11 @@ package provider
 
 import (
 	"bytes"
-	"io/ioutil"
 	"strings"
 	"text/template"
 
 	"github.com/BurntSushi/toml"
 	"github.com/Masterminds/sprig"
-	"github.com/containous/traefik/autogen/gentemplates"
 	"github.com/containous/traefik/config"
 	"github.com/containous/traefik/log"
 	"github.com/containous/traefik/types"
@@ -88,26 +86,6 @@ func (p *BaseProvider) DecodeConfiguration(content string) (*config.Configuratio
 	return configuration, nil
 }
 
-func (p *BaseProvider) getTemplateContent(defaultTemplateFile string) (string, error) {
-	if len(p.Filename) > 0 {
-		buf, err := ioutil.ReadFile(p.Filename)
-		if err != nil {
-			return "", err
-		}
-		return string(buf), nil
-	}
-
-	if strings.HasSuffix(defaultTemplateFile, ".tmpl") {
-		buf, err := gentemplates.Asset(defaultTemplateFile)
-		if err != nil {
-			return "", err
-		}
-		return string(buf), nil
-	}
-
-	return defaultTemplateFile, nil
-}
-
 func split(sep, s string) []string {
 	return strings.Split(s, sep)
 }

provider/docker/config.go

@@ -139,11 +139,12 @@ func (p *Provider) getIPPort(ctx context.Context, container dockerData, serverPo
 
 	if p.UseBindPortIP {
 		portBinding, err := p.getPortBinding(container, serverPort)
-		if err != nil {
+		switch {
+		case err != nil:
 			logger.Infof("Unable to find a binding for container %q, falling back on its internal IP/Port.", container.Name)
-		} else if (portBinding.HostIP == "0.0.0.0") || (len(portBinding.HostIP) == 0) {
+		case portBinding.HostIP == "0.0.0.0" || len(portBinding.HostIP) == 0:
 			logger.Infof("Cannot determine the IP address (got %q) for %q's binding, falling back on its internal IP/Port.", portBinding.HostIP, container.Name)
-		} else {
+		default:
 			ip = portBinding.HostIP
 			port = portBinding.HostPort
 			usedBound = true
@@ -166,9 +167,9 @@ func (p Provider) getIPAddress(ctx context.Context, container dockerData) string
 	logger := log.FromContext(ctx)
 
 	if container.ExtraConf.Docker.Network != "" {
-		networkSettings := container.NetworkSettings
+		settings := container.NetworkSettings
-		if networkSettings.Networks != nil {
+		if settings.Networks != nil {
-			network := networkSettings.Networks[container.ExtraConf.Docker.Network]
+			network := settings.Networks[container.ExtraConf.Docker.Network]
 			if network != nil {
 				return network.Addr
 			}
@@ -251,11 +252,6 @@ func getPort(container dockerData, serverPort string) string {
 	return ""
 }
 
-// Escape beginning slash "/", convert all others to dash "-", and convert underscores "_" to dash "-"
-func getSubDomain(name string) string {
-	return strings.NewReplacer("/", "-", "_", "-").Replace(strings.TrimPrefix(name, "/"))
-}
-
 func getServiceName(container dockerData) string {
 	serviceName := container.ServiceName
 

provider/file/file.go

@@ -47,11 +47,12 @@ func (p *Provider) Provide(configurationChan chan<- config.Message, pool *safe.P
 	if p.Watch {
 		var watchItem string
 
-		if len(p.Directory) > 0 {
+		switch {
+		case len(p.Directory) > 0:
 			watchItem = p.Directory
-		} else if len(p.Filename) > 0 {
+		case len(p.Filename) > 0:
 			watchItem = filepath.Dir(p.Filename)
-		} else {
+		default:
 			watchItem = filepath.Dir(p.TraefikFile)
 		}
 

provider/rest/rest.go

@@ -45,16 +45,16 @@ func (p *Provider) Append(systemRouter *mux.Router) {
 
 			configuration := new(config.Configuration)
 			body, _ := ioutil.ReadAll(request.Body)
-			err := json.Unmarshal(body, configuration)
+
-			if err == nil {
+			if err := json.Unmarshal(body, configuration); err != nil {
-				p.configurationChan <- config.Message{ProviderName: "rest", Configuration: configuration}
-				err := templatesRenderer.JSON(response, http.StatusOK, configuration)
-				if err != nil {
-					log.WithoutContext().Error(err)
-				}
-			} else {
 				log.WithoutContext().Errorf("Error parsing configuration %+v", err)
 				http.Error(response, fmt.Sprintf("%+v", err), http.StatusBadRequest)
+				return
+			}
+
+			p.configurationChan <- config.Message{ProviderName: "rest", Configuration: configuration}
+			if err := templatesRenderer.JSON(response, http.StatusOK, configuration); err != nil {
+				log.WithoutContext().Error(err)
 			}
 		})
 }

server/server_signals.go

@@ -19,8 +19,7 @@ func (s *Server) listenSignals(stop chan bool) {
 		case <-stop:
 			return
 		case sig := <-s.signals:
-			switch sig {
+			if sig == syscall.SIGUSR1 {
-			case syscall.SIGUSR1:
 				log.WithoutContext().Infof("Closing and re-opening log files for rotation: %+v", sig)
 
 				if s.accessLoggerMiddleware != nil {

server/service/service.go

@@ -28,17 +28,6 @@ const (
 	defaultHealthCheckTimeout  = 5 * time.Second
 )
 
-// See oxy/roundrobin/rr.go
-type balancerHandler interface {
-	Servers() []*url.URL
-	ServeHTTP(w http.ResponseWriter, req *http.Request)
-	ServerWeight(u *url.URL) (int, bool)
-	RemoveServer(u *url.URL) error
-	UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error
-	NextServer() (*url.URL, error)
-	Next() http.Handler
-}
-
 // NewManager creates a new Manager
 func NewManager(configs map[string]*config.Service, defaultRoundTripper http.RoundTripper) *Manager {
 	return &Manager{
@@ -148,11 +137,12 @@ func buildHealthCheckOptions(ctx context.Context, lb healthcheck.BalancerHandler
 	interval := defaultHealthCheckInterval
 	if hc.Interval != "" {
 		intervalOverride, err := time.ParseDuration(hc.Interval)
-		if err != nil {
+		switch {
+		case err != nil:
 			logger.Errorf("Illegal health check interval for '%s': %s", backend, err)
-		} else if intervalOverride <= 0 {
+		case intervalOverride <= 0:
 			logger.Errorf("Health check interval smaller than zero for service '%s'", backend)
-		} else {
+		default:
 			interval = intervalOverride
 		}
 	}
@@ -160,11 +150,12 @@ func buildHealthCheckOptions(ctx context.Context, lb healthcheck.BalancerHandler
 	timeout := defaultHealthCheckTimeout
 	if hc.Timeout != "" {
 		timeoutOverride, err := time.ParseDuration(hc.Timeout)
-		if err != nil {
+		switch {
+		case err != nil:
 			logger.Errorf("Illegal health check timeout for backend '%s': %s", backend, err)
-		} else if timeoutOverride <= 0 {
+		case timeoutOverride <= 0:
 			logger.Errorf("Health check timeout smaller than zero for backend '%s', backend", backend)
-		} else {
+		default:
 			timeout = timeoutOverride
 		}
 	}

types/constraints.go

@@ -23,13 +23,14 @@ func NewConstraint(exp string) (*Constraint, error) {
 	sep := ""
 	constraint := &Constraint{}
 
-	if strings.Contains(exp, "==") {
+	switch {
+	case strings.Contains(exp, "=="):
 		sep = "=="
 		constraint.MustMatch = true
-	} else if strings.Contains(exp, "!=") {
+	case strings.Contains(exp, "!="):
 		sep = "!="
 		constraint.MustMatch = false
-	} else {
+	default:
 		return nil, errors.New("constraint expression missing valid operator: '==' or '!='")
 	}