Custom Error Pages (#1675)

* custom error pages

docs/basics.md

@@ -396,6 +396,39 @@ Here is an example of backends and servers definition:
 - `backend2` will forward the traffic to two servers: `http://172.17.0.4:80"` with weight `1` and `http://172.17.0.5:80` with weight `2` using `drr` load-balancing strategy.
 - a circuit breaker is added on `backend1` using the expression `NetworkErrorRatio() > 0.5`: watch error ratio over 10 second sliding window
 
+## Custom Error pages
+
+Custom error pages can be returned, in lieu of the default, according to frontend-configured ranges of HTTP Status codes.
+In the example below, if a 503 status is returned from the frontend "website", the custom error page at http://2.3.4.5/503.html is returned with the actual status code set in the HTTP header.
+Note, the 503.html page itself is not hosted on traefik, but some other infrastructure.   
+
+```toml
+[frontends]
+  [frontends.website]
+  backend = "website"
+  [errors]
+    [error.network]
+    status = ["500-599"]
+    backend = "error"
+    query = "/{status}.html"
+  [frontends.website.routes.website]
+  rule = "Host: website.mydomain.com"
+
+[backends]
+  [backends.website]
+    [backends.website.servers.website]
+    url = "https://1.2.3.4"
+  [backends.error]
+    [backends.error.servers.error]
+    url = "http://2.3.4.5"
+```
+
+In the above example, the error page rendered was based on the status code.
+Instead, the query parameter can also be set to some generic error page like so: `query = "/500s.html"`
+
+Now the 500s.html error page is returned for the configured code range.
+The configured status code ranges are inclusive; that is, in the above example, the 500s.html page will be returned for status codes 500 through, and including, 599.
+
 # Configuration
 
 Træfik's configuration has two parts:

integration/error_pages_test.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"net/http"
+	"os"
+	"os/exec"
+	"time"
+
+	"github.com/containous/traefik/integration/try"
+	"github.com/go-check/check"
+	checker "github.com/vdemeester/shakers"
+)
+
+// ErrorPagesSuite test suites (using libcompose)
+type ErrorPagesSuite struct{ BaseSuite }
+
+func (ep *ErrorPagesSuite) SetUpSuite(c *check.C) {
+	ep.createComposeProject(c, "error_pages")
+	ep.composeProject.Start(c)
+}
+
+func (ep *ErrorPagesSuite) TestSimpleConfiguration(c *check.C) {
+
+	errorPageHost := ep.composeProject.Container(c, "nginx2").NetworkSettings.IPAddress
+	backendHost := ep.composeProject.Container(c, "nginx1").NetworkSettings.IPAddress
+
+	file := ep.adaptFile(c, "fixtures/error_pages/simple.toml", struct {
+		Server1 string
+		Server2 string
+	}{backendHost, errorPageHost})
+	defer os.Remove(file)
+	cmd := exec.Command(traefikBinary, "--configFile="+file)
+
+	err := cmd.Start()
+	c.Assert(err, checker.IsNil)
+	defer cmd.Process.Kill()
+
+	frontendReq, err := http.NewRequest(http.MethodGet, "http://127.0.0.1:80", nil)
+	c.Assert(err, checker.IsNil)
+	frontendReq.Host = "test.local"
+
+	err = try.Request(frontendReq, 2*time.Second, try.BodyContains("nginx"))
+	c.Assert(err, checker.IsNil)
+}
+
+func (ep *ErrorPagesSuite) TestErrorPage(c *check.C) {
+
+	errorPageHost := ep.composeProject.Container(c, "nginx2").NetworkSettings.IPAddress
+	backendHost := ep.composeProject.Container(c, "nginx1").NetworkSettings.IPAddress
+
+	//error.toml contains a mis-configuration of the backend host
+	file := ep.adaptFile(c, "fixtures/error_pages/error.toml", struct {
+		Server1 string
+		Server2 string
+	}{backendHost, errorPageHost})
+	defer os.Remove(file)
+	cmd := exec.Command(traefikBinary, "--configFile="+file)
+
+	err := cmd.Start()
+	c.Assert(err, checker.IsNil)
+	defer cmd.Process.Kill()
+
+	frontendReq, err := http.NewRequest(http.MethodGet, "http://127.0.0.1:80", nil)
+	c.Assert(err, checker.IsNil)
+	frontendReq.Host = "test.local"
+
+	err = try.Request(frontendReq, 2*time.Second, try.BodyContains("An error occurred."))
+	c.Assert(err, checker.IsNil)
+}

integration/fixtures/error_pages/error.toml

@@ -0,0 +1,27 @@
+defaultEntryPoints = ["http"]
+
+logLevel = "DEBUG"
+
+[entryPoints]
+  [entryPoints.http]
+  address = ":80"
+
+[file]
+[backends]
+  [backends.backend1]
+    [backends.backend1.servers.server1]
+    url = "http://{{.Server1}}:8989474"
+  [backends.error]
+    [backends.error.servers.error]
+    url = "http://{{.Server2}}:80"
+[frontends]
+    [frontends.frontend1]
+    passHostHeader = true
+    backend = "backend1"
+    [frontends.frontend1.routes.test_1]
+    rule = "Host:test.local"
+    [frontends.frontend1.errors]
+        [frontends.frontend1.errors.networks]
+        status = ["500-502", "503-599"]
+        backend = "error"
+        query = "/50x.html"

integration/fixtures/error_pages/simple.toml

@@ -0,0 +1,27 @@
+defaultEntryPoints = ["http"]
+
+logLevel = "DEBUG"
+
+[entryPoints]
+  [entryPoints.http]
+  address = ":80"
+
+[file]
+[backends]
+  [backends.backend1]
+    [backends.backend1.servers.server1]
+    url = "http://{{.Server1}}:80"
+  [backends.error]
+    [backends.error.servers.error]
+    url = "http://{{.Server2}}:80"
+[frontends]
+    [frontends.frontend1]
+    passHostHeader = true
+    backend = "backend1"
+    [frontends.frontend1.routes.test_1]
+    rule = "Host:test.local"
+    [frontends.frontend1.errors]
+        [frontends.frontend1.errors.networks]
+        status = ["500-502", "503-599"]
+        backend = "error"
+        query = "/50x.html"

integration/integration_test.go

@@ -38,6 +38,7 @@ func init() {
 	check.Suite(&EurekaSuite{})
 	check.Suite(&AcmeSuite{})
 	check.Suite(&DynamoDBSuite{})
+	check.Suite(&ErrorPagesSuite{})
 }
 
 var traefikBinary = "../dist/traefik"

integration/resources/compose/error_pages.yml

@@ -0,0 +1,4 @@
+nginx1:
+  image: nginx:alpine
+nginx2:
+  image: nginx:alpine

middlewares/error_pages.go

@@ -0,0 +1,77 @@
+package middlewares
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/containous/traefik/log"
+	"github.com/containous/traefik/types"
+	"github.com/vulcand/oxy/forward"
+	"github.com/vulcand/oxy/utils"
+)
+
+//ErrorPagesHandler is a middleware that provides the custom error pages
+type ErrorPagesHandler struct {
+	HTTPCodeRanges     [][2]int
+	BackendURL         string
+	errorPageForwarder *forward.Forwarder
+}
+
+//NewErrorPagesHandler initializes the utils.ErrorHandler for the custom error pages
+func NewErrorPagesHandler(errorPage types.ErrorPage, backendURL string) (*ErrorPagesHandler, error) {
+	fwd, err := forward.New()
+	if err != nil {
+		return nil, err
+	}
+
+	//Break out the http status code ranges into a low int and high int
+	//for ease of use at runtime
+	var blocks [][2]int
+	for _, block := range errorPage.Status {
+		codes := strings.Split(block, "-")
+		//if only a single HTTP code was configured, assume the best and create the correct configuration on the user's behalf
+		if len(codes) == 1 {
+			codes = append(codes, codes[0])
+		}
+		lowCode, err := strconv.Atoi(codes[0])
+		if err != nil {
+			return nil, err
+		}
+		highCode, err := strconv.Atoi(codes[1])
+		if err != nil {
+			return nil, err
+		}
+		blocks = append(blocks, [2]int{lowCode, highCode})
+	}
+	return &ErrorPagesHandler{
+			HTTPCodeRanges:     blocks,
+			BackendURL:         backendURL + errorPage.Query,
+			errorPageForwarder: fwd},
+		nil
+}
+
+func (ep *ErrorPagesHandler) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
+	recorder := newRetryResponseRecorder()
+	recorder.responseWriter = w
+	next.ServeHTTP(recorder, req)
+
+	w.WriteHeader(recorder.Code)
+	//check the recorder code against the configured http status code ranges
+	for _, block := range ep.HTTPCodeRanges {
+		if recorder.Code >= block[0] && recorder.Code <= block[1] {
+			log.Errorf("Caught HTTP Status Code %d, returning error page", recorder.Code)
+			finalURL := strings.Replace(ep.BackendURL, "{status}", strconv.Itoa(recorder.Code), -1)
+			if newReq, err := http.NewRequest(http.MethodGet, finalURL, nil); err != nil {
+				w.Write([]byte(http.StatusText(recorder.Code)))
+			} else {
+				ep.errorPageForwarder.ServeHTTP(w, newReq)
+			}
+			return
+		}
+	}
+
+	//did not catch a configured status code so proceed with the request
+	utils.CopyHeaders(w.Header(), recorder.Header())
+	w.Write(recorder.Body.Bytes())
+}

middlewares/error_pages_test.go

@@ -0,0 +1,140 @@
+package middlewares
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+
+	"github.com/codegangsta/negroni"
+	"github.com/containous/traefik/types"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorPage(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "Test Server")
+	}))
+	defer ts.Close()
+
+	testErrorPage := &types.ErrorPage{Backend: "error", Query: "/test", Status: []string{"500-501", "503-599"}}
+	testHandler, err := NewErrorPagesHandler(*testErrorPage, ts.URL)
+
+	assert.Equal(t, nil, err, "Should be no error")
+	assert.Equal(t, testHandler.BackendURL, ts.URL+"/test", "Should be equal")
+
+	recorder := httptest.NewRecorder()
+	req, err := http.NewRequest("GET", ts.URL+"/test", nil)
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "traefik")
+	})
+	n := negroni.New()
+	n.Use(testHandler)
+	n.UseHandler(handler)
+
+	n.ServeHTTP(recorder, req)
+
+	assert.Equal(t, http.StatusOK, recorder.Code, "HTTP statusOK")
+	assert.Contains(t, recorder.Body.String(), "traefik")
+
+	handler500 := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(500)
+		fmt.Fprintln(w, "oops")
+	})
+	recorder500 := httptest.NewRecorder()
+	n500 := negroni.New()
+	n500.Use(testHandler)
+	n500.UseHandler(handler500)
+
+	n500.ServeHTTP(recorder500, req)
+
+	assert.Equal(t, http.StatusInternalServerError, recorder500.Code, "HTTP status Internal Server Error")
+	assert.Contains(t, recorder500.Body.String(), "Test Server")
+	assert.NotContains(t, recorder500.Body.String(), "oops", "Should not return the oops page")
+
+	handler502 := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(502)
+		fmt.Fprintln(w, "oops")
+	})
+	recorder502 := httptest.NewRecorder()
+	n502 := negroni.New()
+	n502.Use(testHandler)
+	n502.UseHandler(handler502)
+
+	n502.ServeHTTP(recorder502, req)
+
+	assert.Equal(t, http.StatusBadGateway, recorder502.Code, "HTTP status Bad Gateway")
+	assert.Contains(t, recorder502.Body.String(), "oops")
+	assert.NotContains(t, recorder502.Body.String(), "Test Server", "Should return the oops page since we have not configured the 502 code")
+
+}
+
+func TestErrorPageQuery(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.RequestURI() == "/"+strconv.Itoa(503) {
+			fmt.Fprintln(w, "503 Test Server")
+		} else {
+			fmt.Fprintln(w, "Failed")
+		}
+
+	}))
+	defer ts.Close()
+
+	testErrorPage := &types.ErrorPage{Backend: "error", Query: "/{status}", Status: []string{"503-503"}}
+	testHandler, err := NewErrorPagesHandler(*testErrorPage, ts.URL)
+	assert.Equal(t, nil, err, "Should be no error")
+	assert.Equal(t, testHandler.BackendURL, ts.URL+"/{status}", "Should be equal")
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(503)
+		fmt.Fprintln(w, "oops")
+	})
+	recorder := httptest.NewRecorder()
+	req, err := http.NewRequest("GET", ts.URL+"/test", nil)
+	n := negroni.New()
+	n.Use(testHandler)
+	n.UseHandler(handler)
+
+	n.ServeHTTP(recorder, req)
+
+	assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status Service Unavailable")
+	assert.Contains(t, recorder.Body.String(), "503 Test Server")
+	assert.NotContains(t, recorder.Body.String(), "oops", "Should not return the oops page")
+
+}
+
+func TestErrorPageSingleCode(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.RequestURI() == "/"+strconv.Itoa(503) {
+			fmt.Fprintln(w, "503 Test Server")
+		} else {
+			fmt.Fprintln(w, "Failed")
+		}
+
+	}))
+	defer ts.Close()
+
+	testErrorPage := &types.ErrorPage{Backend: "error", Query: "/{status}", Status: []string{"503"}}
+	testHandler, err := NewErrorPagesHandler(*testErrorPage, ts.URL)
+	assert.Equal(t, nil, err, "Should be no error")
+	assert.Equal(t, testHandler.BackendURL, ts.URL+"/{status}", "Should be equal")
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(503)
+		fmt.Fprintln(w, "oops")
+	})
+	recorder := httptest.NewRecorder()
+	req, err := http.NewRequest("GET", ts.URL+"/test", nil)
+	n := negroni.New()
+	n.Use(testHandler)
+	n.UseHandler(handler)
+
+	n.ServeHTTP(recorder, req)
+
+	assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status Service Unavailable")
+	assert.Contains(t, recorder.Body.String(), "503 Test Server")
+	assert.NotContains(t, recorder.Body.String(), "oops", "Should not return the oops page")
+
+}

server/server.go

@@ -772,6 +772,22 @@ func (server *Server) loadConfig(configurations configs, globalConfiguration Glo
 							backendsHealthcheck[frontend.Backend] = healthcheck.NewBackendHealthCheck(*hcOpts)
 						}
 					}
+
+					if len(frontend.Errors) > 0 {
+						for _, errorPage := range frontend.Errors {
+							if configuration.Backends[errorPage.Backend] != nil && configuration.Backends[errorPage.Backend].Servers["error"].URL != "" {
+								errorPageHandler, err := middlewares.NewErrorPagesHandler(errorPage, configuration.Backends[errorPage.Backend].Servers["error"].URL)
+								if err != nil {
+									log.Errorf("Error creating custom error page middleware, %v", err)
+								} else {
+									negroni.Use(errorPageHandler)
+								}
+							} else {
+								log.Errorf("Error Page is configured for Frontend %s, but either Backend %s is not set or Backend URL is missing", frontendName, errorPage.Backend)
+							}
+						}
+					}
+
 					maxConns := configuration.Backends[frontend.Backend].MaxConn
 					if maxConns != nil && maxConns.Amount != 0 {
 						extractFunc, err := utils.NewExtractor(maxConns.ExtractorFunc)

types/types.go

@@ -54,6 +54,13 @@ type Route struct {
 	Rule string `json:"rule,omitempty"`
 }
 
+//ErrorPage holds custom error page configuration
+type ErrorPage struct {
+	Status  []string `json:"status,omitempty"`
+	Backend string   `json:"backend,omitempty"`
+	Query   string   `json:"query,omitempty"`
+}
+
 // Headers holds the custom header configuration
 type Headers struct {
 	CustomRequestHeaders    map[string]string `json:"customRequestHeaders,omitempty"`
@@ -117,6 +124,7 @@ type Frontend struct {
 	BasicAuth            []string             `json:"basicAuth"`
 	WhitelistSourceRange []string             `json:"whitelistSourceRange,omitempty"`
 	Headers              Headers              `json:"headers,omitempty"`
+	Errors               map[string]ErrorPage `json:"errors,omitempty"`
 }
 
 // LoadBalancerMethod holds the method of load balancing to use.