commands: Show server error info in browser

Fixes gohugoio#5284

commands/commandeer.go

@@ -14,20 +14,24 @@
 package commands
 
 import (
+	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
 	"sync"
 	"time"
 
+	"github.com/gohugoio/hugo/livereload"
+
 	"github.com/gohugoio/hugo/config"
 
 	"github.com/spf13/cobra"
 
-	"github.com/spf13/afero"
-
 	"github.com/gohugoio/hugo/hugolib"
+	"github.com/spf13/afero"
+	jww "github.com/spf13/jwalterweatherman"
 
 	"github.com/bep/debounce"
 	"github.com/gohugoio/hugo/common/types"
@@ -72,6 +76,70 @@ type commandeer struct {
 
 	configured bool
 	paused     bool
+
+	errorHandler *errorHandler
+}
+
+type errorHandler struct {
+	logger *log.Logger
+	sync.RWMutex
+	err *buildError
+}
+
+type buildError struct {
+	logger *log.Logger
+	What   string
+	Err    error
+}
+
+func (b buildError) log() {
+	b.logger.Println(b.Error())
+}
+
+func (b buildError) Error() string {
+	return fmt.Sprintf("%s: %s", b.What, b.Err)
+}
+
+func (c *commandeer) getError() *buildError {
+	h := c.errorHandler
+	h.RLock()
+	defer h.RUnlock()
+	return h.err
+}
+
+func (c *commandeer) getErrorWithContext() interface{} {
+	h := c.errorHandler
+	h.RLock()
+	defer h.RUnlock()
+	if h.err == nil {
+		return nil
+	}
+	m := make(map[string]interface{})
+
+	m["Error"] = h.err
+	m["Version"] = hugoVersionString()
+
+	return m
+}
+
+func (c *commandeer) handleError(what string, err error) error {
+	h := c.errorHandler
+	h.Lock()
+	defer h.Unlock()
+
+	if err == nil {
+		h.err = nil
+		return nil
+	}
+
+	h.err = &buildError{logger: h.logger, What: what, Err: err}
+	h.err.log()
+
+	// TODO(bep) server error config
+	// Need to refresh the browser to show the error page.
+	livereload.ForceRefresh()
+
+	return h.err
 }
 
 func (c *commandeer) Set(key string, value interface{}) {
@@ -98,13 +166,23 @@ func newCommandeer(mustHaveConfigFile, running bool, h *hugoBuilderCommon, f fla
 		rebuildDebouncer, _, _ = debounce.New(4 * time.Second)
 	}
 
+	/*var logger *log.Logger
+	if c.Logger != nil {
+		logger = c.Logger.ERROR
+	} else {
+		logger = jww.ERROR
+	}*/
+	// TODO(bep) server error
+	logger := jww.ERROR
+
 	c := &commandeer{
 		h:                   h,
 		ftch:                f,
 		commandeerHugoState: &commandeerHugoState{},
 		doWithCommandeer:    doWithCommandeer,
 		visitedURLs:         types.NewEvictingStringQueue(10),
 		debounce:            rebuildDebouncer,
+		errorHandler:        &errorHandler{logger: logger},
 	}
 
 	return c, c.loadConfig(mustHaveConfigFile, running)

commands/commands.go

@@ -14,8 +14,6 @@
 package commands
 
 import (
-	"os"
-
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/spf13/cobra"
@@ -255,25 +253,3 @@ func checkErr(logger *jww.Notepad, err error, s ...string) {
 	}
 	logger.ERROR.Println(err)
 }
-
-func stopOnErr(logger *jww.Notepad, err error, s ...string) {
-	if err == nil {
-		return
-	}
-
-	defer os.Exit(-1)
-
-	if len(s) == 0 {
-		newMessage := err.Error()
-		// Printing an empty string results in a error with
-		// no message, no bueno.
-		if newMessage != "" {
-			logger.CRITICAL.Println(newMessage)
-		}
-	}
-	for _, message := range s {
-		if message != "" {
-			logger.CRITICAL.Println(message)
-		}
-	}
-}

commands/hugo.go

@@ -24,6 +24,7 @@ import (
 	"syscall"
 
 	"github.com/gohugoio/hugo/hugolib/filesystems"
+	"github.com/pkg/errors"
 
 	"golang.org/x/sync/errgroup"
 
@@ -637,17 +638,17 @@ func (c *commandeer) fullRebuild() {
 	c.commandeerHugoState = &commandeerHugoState{}
 	err := c.loadConfig(true, true)
 	if err != nil {
-		jww.ERROR.Println("Failed to reload config:", err)
+		c.handleError("Failed to reload config", errors.WithStack(err))
 		// Set the processing on pause until the state is recovered.
 		c.paused = true
 	} else {
 		c.paused = false
 	}
 
 	if !c.paused {
-		if err := c.buildSites(); err != nil {
-			jww.ERROR.Println(err)
-		} else if !c.h.buildWatch && !c.Cfg.GetBool("disableLiveReload") {
+		err := c.buildSites()
+		c.handleError("Build failed", errors.WithStack(err))
+		if err == nil && !c.h.buildWatch && !c.Cfg.GetBool("disableLiveReload") {
 			livereload.ForceRefresh()
 		}
 	}
@@ -839,11 +840,12 @@ func (c *commandeer) newWatcher(dirList ...string) (*watcher.Batcher, error) {
 						c.Logger.FEEDBACK.Printf("Syncing all static files\n")
 						_, err := c.copyStatic()
 						if err != nil {
-							stopOnErr(c.Logger, err, "Error copying static files to publish dir")
+							c.handleError("Error copying static files to publish dir", errors.WithStack(err))
+							break
 						}
 					} else {
 						if err := staticSyncer.syncsStaticEvents(staticEvents); err != nil {
-							c.Logger.ERROR.Println(err)
+							c.handleError("Error syncing static files to publish dir", errors.WithStack(err))
 							continue
 						}
 					}
@@ -917,7 +919,7 @@ func (c *commandeer) newWatcher(dirList ...string) (*watcher.Batcher, error) {
 				}
 			case err := <-watcher.Errors:
 				if err != nil {
-					c.Logger.ERROR.Println(err)
+					c.handleError("Error while watching", errors.WithStack(err))
 				}
 			}
 		}

commands/server.go

@@ -316,6 +316,16 @@ func (f *fileServer) createEndpoint(i int) (*http.ServeMux, string, string, erro
 
 	decorate := func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+			// First check the error state
+			err := f.c.getErrorWithContext()
+			if err != nil {
+				errTemplate := defaultBuildErrorTemplate
+				w.WriteHeader(errTemplate.statusCode) // TODO(bep) error server improve
+				errTemplate.buildErrorPage(err, w)
+				return
+			}
+
 			if f.s.noHTTPCache {
 				w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate, max-age=0")
 				w.Header().Set("Pragma", "no-cache")

commands/server_errors.go

@@ -0,0 +1,50 @@
+// Copyright 2018 The Hugo 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 commands
+
+import (
+	"html/template"
+	"io"
+)
+
+type errorTemplate struct {
+	// To text template to produce a nice looking error page in the browser.
+	templ string
+
+	// The default HTTP status code shown for this error.
+	statusCode int
+}
+
+var defaultBuildErrorTemplate = errorTemplate{
+	templ: `<h1>{{ .Error.What }}</h1>
+<pre>{{ .Error.Err }}</pre>
+
+
+<pre>{{ .Error.Err.StackTrace }}</pre>
+
+<small>{{ .Version }}</small>
+
+
+`,
+	statusCode: 500,
+}
+
+func (templ errorTemplate) buildErrorPage(data interface{}, w io.Writer) error {
+	t, err := template.New("").Parse(templ.templ)
+	if err != nil {
+		return err
+	}
+
+	return t.Execute(w, data)
+}

commands/version.go

@@ -14,14 +14,16 @@
 package commands
 
 import (
+	"fmt"
 	"runtime"
 	"strings"
 
+	jww "github.com/spf13/jwalterweatherman"
+
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/resource/tocss/scss"
 	"github.com/spf13/cobra"
-	jww "github.com/spf13/jwalterweatherman"
 )
 
 var _ cmder = (*versionCmd)(nil)
@@ -45,6 +47,10 @@ func newVersionCmd() *versionCmd {
 }
 
 func printHugoVersion() {
+	jww.FEEDBACK.Println(hugoVersionString())
+}
+
+func hugoVersionString() string {
 	program := "Hugo Static Site Generator"
 
 	version := "v" + helpers.CurrentHugoVersion.String()
@@ -64,5 +70,6 @@ func printHugoVersion() {
 		buildDate = "unknown"
 	}
 
-	jww.FEEDBACK.Println(program, version, osArch, "BuildDate:", buildDate)
+	return fmt.Sprintf("%s %s %s BuildDate: %s", program, version, osArch, buildDate)
+
 }

go.mod

@@ -38,6 +38,7 @@ require (
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 // indirect
 	github.com/nicksnyder/go-i18n v1.10.0
 	github.com/olekukonko/tablewriter v0.0.0-20180506121414-d4647c9c7a84
+	github.com/pkg/errors v0.8.0
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/russross/blackfriday v0.0.0-20180804101149-46c73eb196ba
 	github.com/sanity-io/litter v1.1.0

go.sum

@@ -87,6 +87,8 @@ github.com/olekukonko/tablewriter v0.0.0-20180506121414-d4647c9c7a84 h1:fiKJgB4J
 github.com/olekukonko/tablewriter v0.0.0-20180506121414-d4647c9c7a84/go.mod h1:vsDQFd/mU46D+Z4whnwzcISnGGzXWMclvtLoiIKAKIo=
 github.com/pelletier/go-toml v1.2.0 h1:T5zMGML61Wp+FlcbWjRDT7yAxhJNAiPPLOFECq181zc=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday v0.0.0-20180804101149-46c73eb196ba h1:8Vzt8HxRjy7hp1eqPKVoAEPK9npQFW2510qlobGzvi0=