From b11d549fd071def4409c63c0531490372ddeb184 Mon Sep 17 00:00:00 2001
From: Brian Bland <brian.bland@docker.com>
Date: Thu, 8 Jan 2015 16:55:40 -0800
Subject: [PATCH] Adds support for content redirects for layer downloads

Includes a delegate implementation which redirects to the URL generated
by the storagedriver, and a cloudfront implementation.
Satisfies proposal #49
---
 docs/app.go   | 12 ++++++++++++
 docs/layer.go |  6 ++++++
 2 files changed, 18 insertions(+)

diff --git a/docs/app.go b/docs/app.go
index fefeb084..b757b9ab 100644
--- a/docs/app.go
+++ b/docs/app.go
@@ -31,6 +31,8 @@ type App struct {
 
 	tokenProvider tokenProvider
 
+	layerHandler storage.LayerHandler
+
 	accessController auth.AccessController
 }
 
@@ -76,6 +78,16 @@ func NewApp(configuration configuration.Configuration) *App {
 		app.accessController = accessController
 	}
 
+	layerHandlerType := configuration.HTTP.LayerHandler.Type()
+
+	if layerHandlerType != "" {
+		lh, err := storage.GetLayerHandler(layerHandlerType, configuration.HTTP.LayerHandler.Parameters(), driver)
+		if err != nil {
+			panic(fmt.Sprintf("unable to configure layer handler (%s): %v", layerHandlerType, err))
+		}
+		app.layerHandler = lh
+	}
+
 	return app
 }
 
diff --git a/docs/layer.go b/docs/layer.go
index a7c46c31..5d43a1ad 100644
--- a/docs/layer.go
+++ b/docs/layer.go
@@ -58,5 +58,11 @@ func (lh *layerHandler) GetLayer(w http.ResponseWriter, r *http.Request) {
 	}
 	defer layer.Close()
 
+	handler, err := lh.layerHandler.Resolve(layer)
+	if handler != nil {
+		handler.ServeHTTP(w, r)
+		return
+	}
+
 	http.ServeContent(w, r, layer.Digest().String(), layer.CreatedAt(), layer)
 }