Make HTTP middleware easier to use

appengine/cmd/dm/frontend/init.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package frontend
 
 import (
         "fmt"
         "net/http"
         "os"
 
         "golang.org/x/net/context"
 
         "google.golang.org/appengine"
 
-        "github.com/julienschmidt/httprouter"
         "github.com/luci/luci-go/appengine/cmd/dm/deps"
         "github.com/luci/luci-go/appengine/cmd/dm/distributor"
         "github.com/luci/luci-go/appengine/cmd/dm/mutate"
         "github.com/luci/luci-go/appengine/gaeconfig"
         "github.com/luci/luci-go/appengine/gaemiddleware"
         "github.com/luci/luci-go/appengine/tumble"
         "github.com/luci/luci-go/common/config"
         "github.com/luci/luci-go/common/config/impl/filesystem"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/server/discovery"
-        "github.com/luci/luci-go/server/middleware"
         "github.com/luci/luci-go/server/prpc"
+        "github.com/luci/luci-go/server/router"
 )
 
 func addConfigProd(c context.Context) context.Context {
         cfg, err := gaeconfig.New(c)
         switch err {
         case nil:
                 c = config.Set(c, cfg)
         case gaeconfig.ErrNotConfigured:
                 logging.Warningf(c, "luci-config service url not configured. Configure this at /admin/settings/gaeconfig.")
                 fallthrough
         default:
                 panic(err)
         }
         return c
 }
 
-func baseProd(h middleware.Handler) httprouter.Handle {
-        newH := func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-                h(addConfigProd(c), rw, r, p)
-        }
-        return gaemiddleware.BaseProd(newH)
+func baseProd() router.MiddlewareChain {
+        return append(
+                gaemiddleware.BaseProd(),
+                func(c *router.Context, next router.Handler) {
+                        c.Context = addConfigProd(c.Context)
+                        next(c)
+                },
+        )
 }
 
 func addConfigDev(c context.Context) context.Context {
         fpath := os.Getenv("LUCI_DM_CONFIG_BASE_PATH")
         if fpath == "" {
                 panic(fmt.Errorf("LUCI_DM_CONFIG_BASE_PATH must be set in the environment"))
         }
         fs, err := filesystem.New(fpath)
         if err != nil {
                 panic(fmt.Errorf("while setting up LUCI_DM_CONFIG_BASE_PATH: %s", err))
         }
         return config.Set(c, fs)
 }
 
-func baseDev(h middleware.Handler) httprouter.Handle {
-        return gaemiddleware.BaseProd(func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-                h(addConfigDev(c), rw, r, p)
-        })
+func baseDev() router.MiddlewareChain {
+        return append(
+                gaemiddleware.BaseProd(),
+                func(c *router.Context, next router.Handler) {
+                        c.Context = addConfigDev(c.Context)
+                        next(c)
+                },
+        )
 }
 
 func init() {
-        router := httprouter.New()
+        r := router.New()
         tmb := tumble.Service{}
 
         reg := distributor.NewRegistry(nil, mutate.FinishExecutionFn)
 
-        base := baseProd
+        basemw := baseProd()
         tmb.Middleware = func(c context.Context) context.Context {
                 return distributor.WithRegistry(addConfigProd(c), reg)
         }
         if appengine.IsDevAppServer() {
-                base = baseDev
+                basemw = baseDev()
                 tmb.Middleware = func(c context.Context) context.Context {
                         return distributor.WithRegistry(addConfigDev(c), reg)
                 }
         }
 
-        distributor.InstallHandlers(reg, router, base)
+        distributor.InstallHandlers(reg, r, basemw)
 
         svr := prpc.Server{}
         deps.RegisterDepsServer(&svr, reg)
         discovery.Enable(&svr)
-        svr.InstallHandlers(router, base)
-        tmb.InstallHandlers(router)
-        gaemiddleware.InstallHandlers(router, base)
+        svr.InstallHandlers(r, basemw)
+        tmb.InstallHandlers(r)
+        gaemiddleware.InstallHandlers(r, basemw)
 
-        http.Handle("/", router)
+        http.Handle("/", r)
 }