woodpecker/server/web/web.go
Martin W. Kirst 2c1fc4b500
support custom .JS and .CSS files for custom banner messages (white-labeling) (#1781)
This PR introduces two new server configuration options, for providing a
custom .JS and .CSS file.
These can be used to show custom banner messages, add
environment-dependent signals, or simply a corporate logo.

### Motivation (what problem I try to solve)

I'm operating Woodpecker in multiple k8s clusters for different
environments.
When having multiple browser tabs open, I prefer strong indicators for
each environment.
E.g. a red "PROD" banner, or just a blue "QA" banner.
Also, we sometimes need to have the chance for maintenance, and instead
of broadcasting emails,
I prefer a banner message, stating something like: "Heads-up: there's a
planned downtime, next Friday, blabla...".

Also, I like to have the firm's logo visible, which makes Woodpecker
look more like an integral part of our platform.

### Implementation notes

* Two new config options are introduced ```WOODPECKER_CUSTOM_CSS_FILE```
and ```WOODPECKER_CUSTOM_JS_FILE```
* I've piggy-bagged the existing handler for assets, as it seemed to me
a minimally invasive approach
* the option along with an example is documented
* a simple unit test for the Gin-handler ensures some regression safety
* no extra dependencies are introduced

### Visual example

The documented example will look like this.

![Screenshot 2023-05-27 at 17 00
44](https://github.com/woodpecker-ci/woodpecker/assets/1189394/8940392e-463c-4651-a1eb-f017cd3cd64d)

### Areas of uncertainty 

This is my first contribution to Woodpecker and I tried my best to align
with your conventions.
That said, I found myself uncertain about these things and would be glad
about getting feedback.

* The handler tests are somewhat different than the other ones because I
wanted to keep them simple - I hope that still matches your coding
guidelines
* caching the page sometimes will let the browser not recognize changes
and a user must reload. I'm not fully into the details of how caching is
implemented and neither can judge if it's a real problem. Another pair
of eyes would be good.
2023-07-10 12:46:35 +02:00

130 lines
3.6 KiB
Go

// Copyright 2018 Drone.IO Inc.
//
// 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 web
import (
"bytes"
"crypto/md5"
"fmt"
"net/http"
"net/url"
"regexp"
"strings"
"time"
"github.com/gin-gonic/gin"
"github.com/rs/zerolog/log"
"github.com/woodpecker-ci/woodpecker/server"
"github.com/woodpecker-ci/woodpecker/web"
)
// etag is an identifier for a resource version
// it lets caches determine if resource is still the same and not send it again
var (
etag = fmt.Sprintf("%x", md5.Sum([]byte(time.Now().String())))
indexHTML []byte
)
type prefixFS struct {
fs http.FileSystem
prefix string
}
func (f *prefixFS) Open(name string) (http.File, error) {
return f.fs.Open(strings.TrimPrefix(name, f.prefix))
}
// New returns a gin engine to serve the web frontend.
func New() (*gin.Engine, error) {
e := gin.New()
indexHTML = parseIndex()
e.Use(setupCache)
rootURL, _ := url.Parse(server.Config.Server.RootURL)
rootPath := rootURL.Path
httpFS, err := web.HTTPFS()
if err != nil {
return nil, err
}
h := http.FileServer(&prefixFS{httpFS, rootPath})
e.GET(rootPath+"/favicon.svg", redirect(server.Config.Server.RootURL+"/favicons/favicon-light-default.svg", http.StatusPermanentRedirect))
e.GET(rootPath+"/favicons/*filepath", gin.WrapH(h))
e.GET(rootPath+"/assets/*filepath", gin.WrapH(handleCustomFilesAndAssets(h)))
e.NoRoute(handleIndex)
return e, nil
}
func handleCustomFilesAndAssets(assetHandler http.Handler) http.HandlerFunc {
serveFileOrEmptyContent := func(w http.ResponseWriter, r *http.Request, localFileName string) {
if len(localFileName) > 0 {
http.ServeFile(w, r, localFileName)
} else {
// prefer zero content over sending a 404 Not Found
http.ServeContent(w, r, localFileName, time.Now(), bytes.NewReader([]byte{}))
}
}
return func(w http.ResponseWriter, r *http.Request) {
if strings.HasSuffix(r.RequestURI, "/assets/custom.js") {
serveFileOrEmptyContent(w, r, server.Config.Server.CustomJsFile)
} else if strings.HasSuffix(r.RequestURI, "/assets/custom.css") {
serveFileOrEmptyContent(w, r, server.Config.Server.CustomCSSFile)
} else {
assetHandler.ServeHTTP(w, r)
}
}
}
// redirect return gin helper to redirect a request
func redirect(location string, status ...int) func(ctx *gin.Context) {
return func(ctx *gin.Context) {
code := http.StatusFound
if len(status) == 1 {
code = status[0]
}
http.Redirect(ctx.Writer, ctx.Request, location, code)
}
}
func handleIndex(c *gin.Context) {
rw := c.Writer
rw.Header().Set("Content-Type", "text/html; charset=UTF-8")
rw.WriteHeader(http.StatusOK)
if _, err := rw.Write(indexHTML); err != nil {
log.Error().Err(err).Msg("can not write index.html")
}
}
func parseIndex() []byte {
data, err := web.Lookup("index.html")
if err != nil {
log.Fatal().Err(err).Msg("can not find index.html")
}
if server.Config.Server.RootURL == "" {
return data
}
return regexp.MustCompile(`/\S+\.(js|css|png|svg)`).ReplaceAll(data, []byte(server.Config.Server.RootURL+"$0"))
}
func setupCache(c *gin.Context) {
c.Writer.Header().Set("Cache-Control", "public, max-age=31536000")
c.Writer.Header().Del("Expires")
c.Writer.Header().Set("ETag", etag)
}