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Implement common file server to return consistent Content-Type (#191)

* Implement common file server to return consistent Content-Type

When `/etc/mime.types` has a unusual mime type, Content-Type of response becomes the type and you may get unexpected result.
This server returns consistent Content-Type header for js and css files

Signed-off-by: mrasu <m.rasu.hitsuji@gmail.com>
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mrasu authored and brian-brazil committed May 7, 2019
1 parent c873fb1 commit 1ba88736f028e37bc17328369e94a537ae9e0234
Showing with 125 additions and 0 deletions.
  1. +1 −0 README.md
  2. +41 −0 server/static_file_server.go
  3. +83 −0 server/static_file_server_test.go
@@ -9,4 +9,5 @@ components and libraries.
* **log**: A logging wrapper around [logrus](https://github.com/sirupsen/logrus)
* **model**: Shared data structures
* **route**: A routing wrapper around [httprouter](https://github.com/julienschmidt/httprouter) using `context.Context`
* **server**: Common servers
* **version**: Version information and metrics
@@ -0,0 +1,41 @@
// Copyright 2019 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
"net/http"
"path/filepath"
)

var mimeTypes = map[string]string{
".js": "application/javascript",
".css": "text/css",
".png": "image/png",
".jpg": "image/jpeg",
".gif": "image/gif",
}

func StaticFileServer(root http.FileSystem) http.Handler {
return http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
fileExt := filepath.Ext(r.URL.Path)

if t, ok := mimeTypes[fileExt]; ok {
w.Header().Set("Content-Type", t)
}

http.FileServer(root).ServeHTTP(w, r)
},
)
}
@@ -0,0 +1,83 @@
// Copyright 2019 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
"net/http"
"net/http/httptest"
"testing"
)

type dummyFileSystem struct{}

func (fs dummyFileSystem) Open(path string) (http.File, error) {
return http.Dir(".").Open(".")
}

func TestServeHttp(t *testing.T) {
cases := []struct {
name string
path string
contentType string
}{
{
name: "normal file",
path: "index.html",
contentType: "",
},
{
name: "javascript",
path: "test.js",
contentType: "application/javascript",
},
{
name: "css",
path: "test.css",
contentType: "text/css",
},
{
name: "png",
path: "test.png",
contentType: "image/png",
},
{
name: "jpg",
path: "test.jpg",
contentType: "image/jpeg",
},
{
name: "gif",
path: "test.gif",
contentType: "image/gif",
},
}

for _, c := range cases {
t.Run(c.name, func(t *testing.T) {
rr := httptest.NewRecorder()
req, err := http.NewRequest("GET", "http://localhost/"+c.path, nil)

if err != nil {
t.Fatal(err)
}

s := StaticFileServer(dummyFileSystem{})
s.ServeHTTP(rr, req)

if rr.Header().Get("Content-Type") != c.contentType {
t.Fatalf("Unexpected Content-Type: %s", rr.Header().Get("Content-Type"))
}
})
}
}

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