chore: 404 Requests to workspace proxy direct back to the primary (#7353)

* chore: 404 Requests to workspace proxy direct back to the primary

* Remove unnecessary sprintf

enterprise/wsproxy/wsproxy.go

@@ -10,8 +10,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/coder/coder/coderd/httpapi"
-
 	"github.com/go-chi/chi/v5"
 	"github.com/google/uuid"
 	"github.com/prometheus/client_golang/prometheus"
@@ -20,12 +18,14 @@ import (
 
 	"cdr.dev/slog"
 	"github.com/coder/coder/buildinfo"
+	"github.com/coder/coder/coderd/httpapi"
 	"github.com/coder/coder/coderd/httpmw"
 	"github.com/coder/coder/coderd/tracing"
 	"github.com/coder/coder/coderd/workspaceapps"
 	"github.com/coder/coder/coderd/wsconncache"
 	"github.com/coder/coder/codersdk"
 	"github.com/coder/coder/enterprise/wsproxy/wsproxysdk"
+	"github.com/coder/coder/site"
 )
 
 type Options struct {
@@ -233,6 +233,15 @@ func New(ctx context.Context, opts *Options) (*Server, error) {
 	r.Get("/healthz", func(w http.ResponseWriter, r *http.Request) { _, _ = w.Write([]byte("OK")) })
 	// TODO: @emyrk should this be authenticated or debounced?
 	r.Get("/healthz-report", s.healthReport)
+	r.NotFound(func(rw http.ResponseWriter, r *http.Request) {
+		site.RenderStaticErrorPage(rw, r, site.ErrorPageData{
+			Status:       404,
+			Title:        "Route Not Found",
+			Description:  "The route you requested does not exist on this workspace proxy. Maybe you intended to make this request to the primary dashboard? Click below to be redirected to the primary site.",
+			RetryEnabled: false,
+			DashboardURL: opts.DashboardURL.String(),
+		})
+	})
 
 	return s, nil
 }