FileFromFS

[nikandfor]

I was missing feature of Serving file from http.FileSystem.

Use cases:

• Serve file by alias without redirection and opening file by hands.
• Return help page on root of /api/ handlers.
• Choose FileSystem dynamically.

[codecov]

Codecov Report

Merging #2112 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2112   +/-   ##
=======================================
  Coverage   98.38%   98.38%           
=======================================
  Files          41       41           
  Lines        2290     2296    +6     
=======================================
+ Hits         2253     2259    +6     
  Misses         21       21           
  Partials       16       16           

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[nikandfor]

Hi! I'm just remembering about my PR)

[thinkerou]

LGTM

[thinkerou]

need @appleboy review the PR, thanks1

[baurine]

Hi @nikandfor , can you help add more detail for this part:

	var fs http.FileSystem = // ...
	router.GET("/fs/file", func(c *gin.Context) {
		c.FileFromFS("fs/file.go", fs)
	})

What the exact sample content for // ..., how fs/file.go locate in fs?

I tried many cases, they all don't work for me, my sample code:

	endpoint := r.Group("/diagnose")
	endpoint.StaticFS("/assets", http.Dir("ui/build"))
	var fs http.FileSystem = http.Dir("ui/build")
	endpoint.GET("/reports/detail", func(c *gin.Context) {
		// c.File("ui/build/index.html") // this line code can work well
		c.FileFromFS("ui/build/index.html", fs)
	})

For the first parameter of c.FileFormFS(), I tried ui/build/index.html, ./index.html, index.html, build/index.html, all I failed to get the correct response, but the c.File("ui/build/index.html") can success.

Thank you!

[baurine]

After diving into the source code, I found we just can't use index.html, it will be redirected, the source code in fs.go#serverFile() method.

// name is '/'-separated, not filepath.Separator.
func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirect bool) {
	const indexPage = "/index.html"

	// redirect .../index.html to .../
	// can't use Redirect() because that would make the path absolute,
	// which would be a problem running under StripPrefix
	if strings.HasSuffix(r.URL.Path, indexPage) {
		localRedirect(w, r, "./")
		return
	}

So I change the index.html name to report.html and works by following code:

	endpoint := r.Group("/diagnose")
	endpoint.StaticFS("/assets", http.Dir("ui/build"))
	var fs http.FileSystem = http.Dir("ui/build")
	endpoint.GET("/reports/detail", func(c *gin.Context) {
		c.FileFromFS("report.html", fs)
	})

[nikandfor]

@baurine It's really interesting finding.
Would you find solution at your project code?
How do you think if we should add check at gin.Context.FileFromFS? like

const indexPage = "index.html"

filepath = strings.TrimSuffix(filepath, indexPage)

[baurine]

hi @nikandfor , I just rename my index.html to report.html to workaround it...

[nikandfor]

@thinkerou how do you think, do we need to add some fix to avoid such situations in the future?

[ddvk]

this was quite annoying, trying to serve an embedded asset called index.html resulting in too many redirects, until finding out what was causing the problem.

Maybe add a comment or throw an error

[lenghan4real]

@thinkerou how do you think, do we need to add some fix to avoid such situations in the future?

I think so, rename index.html is quite annoying.