英文:
Creating a tar file to be served via Google App Engine
问题
我正在为使用Go的Google AppEngine编写一个应用程序，并且需要将一堆文件打包成tar文件，在用户访问特定URL时提供给他们。目前这些文件是静态的，所以我可以在上传到服务器之前将它们打包成tar文件来解决这个问题。将来我希望在打包之前动态地修改它们，所以我想学习如何在请求时打包和提供静态文件。
在我的init()函数中，我有以下代码：
http.HandleFunc("/download.tar", tarit)
tarit函数是我遇到问题的函数，目前它的代码如下：
func tarit(w http.ResponseWriter, r *http.Request) {
tarball := tar.NewWriter(w)
defer tarball.Close()
info, err := os.Stat("/files")
if err != nil {
return
}
var baseDir string
if info.IsDir() {
baseDir = filepath.Base("/files")
}
filepath.Walk("/files", func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
header, err := tar.FileInfoHeader(info, info.Name())
if err != nil {
return err
}
if baseDir != "" {
header.Name = filepath.Join(baseDir, strings.TrimPrefix(path, "/files"))
}
if err := tarball.WriteHeader(header); err != nil {
return err
}
if info.IsDir() {
return nil
}
file, err := os.Open(path)
if err != nil {
return err
}
defer file.Close()
_, err = io.Copy(tarball, file)
return err
})
}
我要添加到tar文件中的文件位于/files目录下，并且我已将此文件夹添加为app.yaml中的static_dir。
当访问适当的URL时，浏览器下载的tar文件只有1 KB大小，并且看起来是空的。
如果有人能指出我做错了什么，或者我理解错了什么，我将非常感激。我也很乐意提供您需要的任何其他细节。
谢谢！
英文:
I'm writing an application for Google AppEngine using Go, and need to tar together a bunch of files to serve to the user when they navigate to a particular URL. At the moment the files are static, and so I could solve this problem by tarring them before upload to the server. In the future I would like to dynamically alter them before tarring, and so would like to learn how to tar & serve the static files on request.
In my init() function I have the following line:
http.HandleFunc("/download.tar", tarit)
The function tarit is the one I am having a problem with, and it currently looks like the following:
func tarit(w http.ResponseWriter, r *http.Request) {
tarball := tar.NewWriter(w)
defer tarball.Close()
info, err := os.Stat("/files")
if err != nil {
return
}
var baseDir string
if info.IsDir() {
baseDir = filepath.Base("/files")
}
filepath.Walk("/files", func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
header, err := tar.FileInfoHeader(info, info.Name())
if err != nil {
return err
}
if baseDir != "" {
header.Name = filepath.Join(baseDir, strings.TrimPrefix(path, "/files"))
}
if err := tarball.WriteHeader(header); err != nil {
return err
}
if info.IsDir() {
return nil
}
file, err := os.Open(path)
if err != nil {
return err
}
defer file.Close()
_, err = io.Copy(tarball, file)
return err
})
}
The files I am trying to add to the tarball are located in /files, and I've added this folder as a static_dir in the app.yaml.
When navigating to the appropriate URL, the browser downloads a tar file that is only 1 KB in size, and appears to be empty.
I would very much appreciate if someone could point out where I am going wrong, or what I am misunderstanding. I'd also be very happy to provide any other details that you would like.
Thanks!
答案1
得分: 0
请将路径指定为相对于包含 app.yaml 文件的目录的路径。在发布的代码中，路径是绝对路径 "/files"。也许你应该将其更改为 "files"。
记录从 os.Stat 和 filepath.Walk 返回的错误。这些错误可能会帮助你找到问题所在。
英文:
Specify directories using paths relative to the directory containing app.yaml. The path in the posted code is the absolute path "/files". Perhaps you should change it to "files".
Log the errors returned from os.Stat and filepath.Walk. The errors will probably lead you to the problem.
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