Initial distributor implementation

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"
 )
 
-func base(h middleware.Handler) httprouter.Handle {
+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) {
-                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.")
-                default:
-                        panic(err)
-                }
-                h(c, rw, r, p)
+                h(addConfigProd(c), rw, r, p)
         }
         return gaemiddleware.BaseProd(newH)
 }
 
+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 init() {
         router := httprouter.New()
         tmb := tumble.Service{}
 
+        reg := distributor.NewRegistry(nil, mutate.FinishExecutionFn)
+
+        base := baseProd
+        tmb.Middleware = func(c context.Context) context.Context {
+                return distributor.WithRegistry(addConfigProd(c), reg)
+        }
+        if appengine.IsDevAppServer() {
+                base = baseDev
+                tmb.Middleware = func(c context.Context) context.Context {
+                        return distributor.WithRegistry(addConfigDev(c), reg)
+                }
+        }
+
+        distributor.InstallHandlers(reg, router, base)
+
         svr := prpc.Server{}
-        deps.RegisterDepsServer(&svr)
+        deps.RegisterDepsServer(&svr, reg)
         discovery.Enable(&svr)
-
         svr.InstallHandlers(router, base)
         tmb.InstallHandlers(router)
         gaemiddleware.InstallHandlers(router, base)
 
         http.Handle("/", router)
 }