From 4c999cd5a27535bb692a66c24531f2637380431b Mon Sep 17 00:00:00 2001
From: Rob Watson <rob@netflux.io>
Date: Fri, 26 Nov 2021 05:11:49 +0100
Subject: [PATCH] Configure backend to serve assets over HTTP

---
 backend/.env.example     |  3 +++
 backend/config/config.go |  4 ++++
 backend/server/server.go | 17 ++++++++++++++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/backend/.env.example b/backend/.env.example
index 752a9f9..c60e03e 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -6,3 +6,6 @@ AWS_REGION=
 S3_BUCKET=
 
 DATABASE_URL=
+
+# If set, files in this location will be served over HTTP at /.
+ASSETS_HTTP_BASE_PATH=
diff --git a/backend/config/config.go b/backend/config/config.go
index 5684fa4..4918cfe 100644
--- a/backend/config/config.go
+++ b/backend/config/config.go
@@ -20,6 +20,7 @@ type Config struct {
 	AWSSecretAccessKey string
 	AWSRegion          string
 	S3Bucket           string
+	AssetsHTTPBasePath string
 }
 
 func NewFromEnv() (Config, error) {
@@ -61,6 +62,8 @@ func NewFromEnv() (Config, error) {
 		return Config{}, errors.New("S3_BUCKET not set")
 	}
 
+	assetsHTTPBasePath := os.Getenv("ASSETS_HTTP_BASE_PATH")
+
 	return Config{
 		Environment:        env,
 		DatabaseURL:        databaseURL,
@@ -68,5 +71,6 @@ func NewFromEnv() (Config, error) {
 		AWSSecretAccessKey: awsSecretAccessKey,
 		AWSRegion:          awsRegion,
 		S3Bucket:           s3Bucket,
+		AssetsHTTPBasePath: assetsHTTPBasePath,
 	}, nil
 }
diff --git a/backend/server/server.go b/backend/server/server.go
index b9cea9c..3c49350 100644
--- a/backend/server/server.go
+++ b/backend/server/server.go
@@ -247,13 +247,28 @@ func Start(options Options) error {
 	// TODO: configure CORS
 	grpcWebServer := grpcweb.WrapServer(grpcServer, grpcweb.WithOriginFunc(func(string) bool { return true }))
 
+	log := logger.Sugar()
+	fileHandler := http.NotFoundHandler()
+	if options.Config.AssetsHTTPBasePath != "" {
+		log.With("basePath", options.Config.AssetsHTTPBasePath).Info("Configured to serve assets over HTTP")
+		fileHandler = http.FileServer(http.Dir(options.Config.AssetsHTTPBasePath))
+	}
+
 	httpServer := http.Server{
 		Addr:         options.BindAddr,
 		ReadTimeout:  options.Timeout,
 		WriteTimeout: options.Timeout,
-		Handler:      http.HandlerFunc(grpcWebServer.ServeHTTP),
+		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if !grpcWebServer.IsGrpcWebRequest(r) && !grpcWebServer.IsAcceptableGrpcCorsRequest(r) {
+				fileHandler.ServeHTTP(w, r)
+				return
+			}
+			grpcWebServer.ServeHTTP(w, r)
+		}),
 	}
 
+	log.Infof("Listening at %s", options.BindAddr)
+
 	return httpServer.ListenAndServe()
 }