feat: global error handler with template rendering

internal/proxy/director/context.go

@@ -2,10 +2,12 @@ package director
 
 import (
 	"context"
+	"net/http"
 	"net/url"
 
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
 )
 
 type contextKey string
@@ -14,6 +16,7 @@ const (
 	contextKeyProxy       contextKey = "proxy"
 	contextKeyLayers      contextKey = "layers"
 	contextKeyOriginalURL contextKey = "originalURL"
+	contextKeyHandleError contextKey = "handleError"
 )
 
 var (
@@ -60,3 +63,22 @@ func ctxValue[T any](ctx context.Context, key contextKey) (T, error) {
 
 	return value, nil
 }
+
+type HandleErrorFunc func(w http.ResponseWriter, r *http.Request, status int, err error)
+
+func withHandleError(ctx context.Context, fn HandleErrorFunc) context.Context {
+	return context.WithValue(ctx, contextKeyHandleError, fn)
+}
+
+func HandleError(ctx context.Context, w http.ResponseWriter, r *http.Request, status int, err error) {
+	err = errors.WithStack(err)
+
+	fn, ok := ctx.Value(contextKeyHandleError).(HandleErrorFunc)
+	if !ok {
+		logger.Error(ctx, err.Error(), logger.CapturedE(err))
+		http.Error(w, http.StatusText(status), status)
+		return
+	}
+
+	fn(w, r, status, err)
+}

internal/proxy/director/director.go

@@ -22,6 +22,8 @@ type Director struct {
 
 	proxyCache cache.Cache[string, []*store.Proxy]
 	layerCache cache.Cache[string, []*store.Layer]
+
+	handleError HandleErrorFunc
 }
 
 func (d *Director) rewriteRequest(r *http.Request) (*http.Request, error) {
@@ -33,7 +35,6 @@ func (d *Director) rewriteRequest(r *http.Request) (*http.Request, error) {
 	}
 
 	url := getRequestURL(r)
-
 	ctx = withOriginalURL(ctx, url)
 	ctx = logger.With(ctx, logger.F("url", url.String()))
 
@@ -169,6 +170,7 @@ func (d *Director) getLayers(ctx context.Context, proxyName store.ProxyName) ([]
 func (d *Director) RequestTransformer() proxy.RequestTransformer {
 	return func(r *http.Request) {
 		ctx := r.Context()
+
 		layers, err := ctxLayers(ctx)
 		if err != nil {
 			if errors.Is(err, errContextKeyNotFound) {
@@ -225,15 +227,16 @@ func (d *Director) ResponseTransformer() proxy.ResponseTransformer {
 func (d *Director) Middleware() proxy.Middleware {
 	return func(next http.Handler) http.Handler {
 		fn := func(w http.ResponseWriter, r *http.Request) {
+			ctx := withHandleError(r.Context(), d.handleError)
+			r = r.WithContext(ctx)
+
 			r, err := d.rewriteRequest(r)
 			if err != nil {
-				logger.Error(r.Context(), "could not rewrite request", logger.CapturedE(errors.WithStack(err)))
+				HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not rewrite request"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
-			ctx := r.Context()
+			ctx = r.Context()
 
 			layers, err := ctxLayers(ctx)
 			if err != nil {
@@ -241,9 +244,7 @@ func (d *Director) Middleware() proxy.Middleware {
 					return
 				}
 
-				logger.Error(ctx, "could not retrieve proxy and layers from context", logger.CapturedE(errors.WithStack(err)))
+				HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not retrieve proxy and layers from context"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
@@ -278,5 +279,6 @@ func New(proxyRepository store.ProxyRepository, layerRepository store.LayerRepos
 		layerRegistry:   registry,
 		proxyCache:      opts.ProxyCache,
 		layerCache:      opts.LayerCache,
+		handleError:     opts.HandleError,
 	}
 }

internal/proxy/director/layer/authn/layer.go

@@ -1,7 +1,9 @@
 package authn
 
 import (
+	"bytes"
 	"html/template"
+	"io"
 	"net/http"
 	"path/filepath"
 
@@ -29,9 +31,7 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 
 			options, err := fromStoreOptions(layer.Options)
 			if err != nil {
-				logger.Error(ctx, "could not parse layer options", logger.CapturedE(errors.WithStack(err)))
+				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not parse layer options"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
@@ -162,20 +162,22 @@ func (l *Layer) renderPage(w http.ResponseWriter, r *http.Request, page string,
 
 	tmpl, err := template.New("").Funcs(sprig.FuncMap()).ParseGlob(pattern)
 	if err != nil {
-		logger.Error(ctx, "could not load authn templates", logger.CapturedE(errors.WithStack(err)))
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not load authn templates"))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 		return
 	}
 
 	w.Header().Add("Cache-Control", "no-cache")
 
-	if err := tmpl.ExecuteTemplate(w, block, templateData); err != nil {
+	var buf bytes.Buffer
-		logger.Error(ctx, "could not render authn page", logger.CapturedE(errors.WithStack(err)))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
+	if err := tmpl.ExecuteTemplate(w, block, templateData); err != nil {
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not render authn page"))
 		return
 	}
+
+	if _, err := io.Copy(w, &buf); err != nil {
+		logger.Error(ctx, "could not write authn page", logger.CapturedE(errors.WithStack(err)))
+	}
 }
 
 // LayerType implements director.MiddlewareLayer

internal/proxy/director/layer/authn/oidc/authenticator.go

@@ -86,7 +86,7 @@ func (a *Authenticator) PreAuthentication(w http.ResponseWriter, r *http.Request
 		if postLogoutRedirectURL != "" {
 			isAuthorized := slices.Contains(options.OIDC.PostLogoutRedirectURLs, postLogoutRedirectURL)
 			if !isAuthorized {
-				http.Error(w, "unauthorized post-logout redirect", http.StatusBadRequest)
+				director.HandleError(ctx, w, r, http.StatusBadRequest, errors.New("unauthorized post-logout redirect"))
 				return errors.WithStack(authn.ErrSkipRequest)
 			}
 		}

internal/proxy/director/layer/authn/oidc/client.go

@@ -6,6 +6,7 @@ import (
 	"net/url"
 	"strings"
 
+	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
 	"github.com/coreos/go-oidc/v3/oidc"
 	"github.com/dchest/uniuri"
 	"github.com/gorilla/sessions"
@@ -68,8 +69,7 @@ func (c *Client) login(w http.ResponseWriter, r *http.Request, sess *sessions.Se
 	sess.Values[sessionKeyPostLoginRedirectURL] = postLoginRedirectURL
 
 	if err := sess.Save(r, w); err != nil {
-		logger.Error(ctx, "could not save session", logger.CapturedE(errors.WithStack(err)))
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not save session"))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
 		return
 	}

internal/proxy/director/layer/queue/queue.go

@@ -1,9 +1,11 @@
 package queue
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"html/template"
+	"io"
 	"math/rand"
 	"net/http"
 	"path/filepath"
@@ -52,9 +54,7 @@ func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
 
 			options, err := fromStoreOptions(layer.Options, q.defaultKeepAlive)
 			if err != nil {
-				logger.Error(ctx, "could not parse layer options", logger.CapturedE(errors.WithStack(err)))
+				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not parse layer options"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
@@ -89,9 +89,7 @@ func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
 
 			rank, err := q.adapter.Touch(ctx, queueName, sessionID)
 			if err != nil {
-				logger.Error(ctx, "could not retrieve session rank", logger.CapturedE(errors.WithStack(err)))
+				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not retrieve session rank"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
@@ -144,9 +142,7 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 
 	status, err := q.adapter.Status(ctx, queueName)
 	if err != nil {
-		logger.Error(ctx, "could not retrieve queue status", logger.CapturedE(errors.WithStack(err)))
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not retrieve queue status"))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 		return
 	}
 
@@ -166,9 +162,7 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 	})
 
 	if q.tmpl == nil {
-		logger.Error(ctx, "queue page templates not loaded", logger.CapturedE(errors.WithStack(err)))
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("queue page templates not loaded"))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 		return
 	}
 
@@ -194,12 +188,16 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 	w.Header().Add("Retry-After", strconv.FormatInt(int64(refreshRate.Seconds()), 10))
 	w.WriteHeader(http.StatusServiceUnavailable)
 
-	if err := q.tmpl.ExecuteTemplate(w, "queue", templateData); err != nil {
+	var buf bytes.Buffer
-		logger.Error(ctx, "could not render queue page", logger.CapturedE(errors.WithStack(err)))
-		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
+	if err := q.tmpl.ExecuteTemplate(&buf, "queue", templateData); err != nil {
+		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not render queue page"))
 		return
 	}
+
+	if _, err := io.Copy(w, &buf); err != nil {
+		logger.Error(ctx, "could not write queue page", logger.CapturedE(errors.WithStack(err)))
+	}
 }
 
 func (q *Queue) refreshQueue(ctx context.Context, layerName store.LayerName, keepAlive time.Duration) {

internal/proxy/director/layer/rewriter/layer.go

@@ -11,7 +11,6 @@ import (
 	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/pkg/errors"
-	"gitlab.com/wpetit/goweb/logger"
 )
 
 const LayerType store.LayerType = "rewriter"
@@ -32,9 +31,7 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 
 			options, err := fromStoreOptions(layer.Options)
 			if err != nil {
-				logger.Error(ctx, "could not parse layer options", logger.CapturedE(errors.WithStack(err)))
+				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.New("could not parse layer options"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
-
 				return
 			}
 
@@ -52,8 +49,7 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 					return
 				}
 
-				logger.Error(ctx, "could not apply request rules", logger.CapturedE(errors.WithStack(err)))
+				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not apply request rules"))
-				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
 				return
 			}

internal/proxy/director/options.go

@@ -1,18 +1,21 @@
 package director
 
 import (
+	"net/http"
 	"time"
 
 	"forge.cadoles.com/cadoles/bouncer/internal/cache"
 	"forge.cadoles.com/cadoles/bouncer/internal/cache/memory"
 	"forge.cadoles.com/cadoles/bouncer/internal/cache/ttl"
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
+	"gitlab.com/wpetit/goweb/logger"
 )
 
 type Options struct {
 	Layers      []Layer
 	ProxyCache  cache.Cache[string, []*store.Proxy]
 	LayerCache  cache.Cache[string, []*store.Layer]
+	HandleError HandleErrorFunc
 }
 
 type OptionFunc func(opts *Options)
@@ -30,6 +33,10 @@ func NewOptions(funcs ...OptionFunc) *Options {
 			memory.NewCache[string, time.Time](),
 			30*time.Second,
 		),
+		HandleError: func(w http.ResponseWriter, r *http.Request, status int, err error) {
+			logger.Error(r.Context(), err.Error(), logger.CapturedE(err))
+			http.Error(w, http.StatusText(status), status)
+		},
 	}
 
 	for _, fn := range funcs {
@@ -56,3 +63,9 @@ func WithLayerCache(cache cache.Cache[string, []*store.Layer]) OptionFunc {
 		opts.LayerCache = cache
 	}
 }
+
+func WithHandleErrorFunc(fn HandleErrorFunc) OptionFunc {
+	return func(opts *Options) {
+		opts.HandleError = fn
+	}
+}

internal/proxy/server.go

@@ -1,9 +1,11 @@
 package proxy
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"html/template"
+	"io"
 	"log"
 	"net"
 	"net/http"
@@ -23,7 +25,6 @@ import (
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
 
 	"github.com/Masterminds/sprig/v3"
-	"github.com/getsentry/sentry-go"
 	sentryhttp "github.com/getsentry/sentry-go/http"
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
@@ -112,6 +113,7 @@ func (s *Server) run(parentCtx context.Context, addrs chan net.Addr, errs chan e
 				s.directorCacheTTL,
 			),
 		),
+		director.WithHandleErrorFunc(s.handleError),
 	)
 
 	if s.serverConfig.HTTP.UseRealIP {
@@ -217,27 +219,24 @@ func (s *Server) createReverseProxy(ctx context.Context, target *url.URL) *httpu
 	httpTransport.DialContext = dialer.DialContext
 
 	reverseProxy.Transport = httpTransport
-	reverseProxy.ErrorHandler = s.handleError
+	reverseProxy.ErrorHandler = s.handleProxyError
 
 	return reverseProxy
 }
 
 func (s *Server) handleDefault(w http.ResponseWriter, r *http.Request) {
-	err := errors.Errorf("no proxy target found")
+	s.handleError(w, r, http.StatusBadGateway, errors.Errorf("no proxy target found"))
-
-	logger.Error(r.Context(), "proxy error", logger.CapturedE(err))
-	sentry.CaptureException(err)
-
-	s.renderErrorPage(w, r, err, http.StatusBadGateway, http.StatusText(http.StatusBadGateway))
 }
 
-func (s *Server) handleError(w http.ResponseWriter, r *http.Request, err error) {
+func (s *Server) handleError(w http.ResponseWriter, r *http.Request, status int, err error) {
 	err = errors.WithStack(err)
+	logger.Error(r.Context(), err.Error(), logger.CapturedE(err))
 
-	logger.Error(r.Context(), "proxy error", logger.CapturedE(err))
+	s.renderErrorPage(w, r, err, status, http.StatusText(status))
-	sentry.CaptureException(err)
+}
 
-	s.renderErrorPage(w, r, err, http.StatusBadGateway, http.StatusText(http.StatusBadGateway))
+func (s *Server) handleProxyError(w http.ResponseWriter, r *http.Request, err error) {
+	s.handleError(w, r, http.StatusBadGateway, err)
 }
 
 func (s *Server) renderErrorPage(w http.ResponseWriter, r *http.Request, err error, statusCode int, status string) {
@@ -288,12 +287,18 @@ func (s *Server) renderPage(w http.ResponseWriter, r *http.Request, page string,
 		return
 	}
 
-	if err := blockTmpl.Execute(w, templateData); err != nil {
+	var buf bytes.Buffer
+
+	if err := blockTmpl.Execute(&buf, templateData); err != nil {
 		logger.Error(ctx, "could not render proxy page", logger.CapturedE(errors.WithStack(err)))
 		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
 		return
 	}
+
+	if _, err := io.Copy(w, &buf); err != nil {
+		logger.Error(ctx, "could not write page", logger.CapturedE(errors.WithStack(err)))
+	}
 }
 
 func NewServer(funcs ...OptionFunc) *Server {

templates/error.gohtml

@@ -76,14 +76,26 @@
         margin-top: 2em;
         text-align: right;
       }
+
+      .stacktrace {
+        max-height: 250px;
+        overflow-y: auto;
+        background-color: #dca0a0;
+        padding: 0 10px;
+        border-radius: 5px;
+        margin-top: 10px;
+      }
     </style>
   </head>
   <body>
     <div id="container">
       <div id="card">
-        <h2 class="title">{{ $title }}</h2>
+        <h2 class="title">⚠ {{ $title }}</h2>
         {{ if .Debug }}
-        <pre>{{ .Err }}</pre>
+        <h3>Stack Trace</h3>
+        <div class="stacktrace">
+          <pre>{{ printf "%+v" .Err }}</pre>
+        </div>
         {{ end }}
         <p class="footer">
           Propulsé par