/// note | Technical Details

The ASGI specification defines a `root_path` for this use case.

And the `--root-path` command line option provides that `root_path`.

///

### Checking the current `root_path` { #checking-the-current-root-path }

You can get the current `root_path` used by your application for each request, it is part of the `scope` dictionary (that's part of the ASGI spec).

### Technical Details: `root_path` { #technical-details-root-path }

When you mount a sub-application as described above, FastAPI will take care of communicating the mount path for the sub-application using a mechanism from the ASGI specification called a `root_path`.

That way, the sub-application will know to use that path prefix for the docs UI.

## 0.56.0

* Add support for ASGI `root_path`:
    * Use `root_path` internally for mounted applications, so that OpenAPI and the docs UI works automatically without extra configurations and parameters.

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

	if err = os.MkdirAll(pathJoin(rootPath, minioMetaBucket), os.FileMode(0o755)); err != nil {
		t.Fatal(err)
	}

	if err = os.WriteFile(pathJoin(rootPath, minioMetaBucket, formatConfigFile), b, os.FileMode(0o644)); err != nil {
		t.Fatal(err)
	}

	formatData, _, err := formatErasureMigrate(rootPath)
	if err != nil {
		t.Fatal(err)
	}

		URL:    u,
	}
	if !guessIsRPCReq(r) {
		t.Fatal("Test shouldn't fail for a possible net/rpc request.")
	}
	r = &http.Request{
		Proto:  "HTTP/1.1",
		Method: http.MethodGet,
		URL:    &url.URL{Path: grid.RoutePath},
	}
	if !guessIsRPCReq(r) {
		t.Fatal("Grid RPC path not detected")
	}
	r = &http.Request{
		Proto:  "HTTP/1.1",
		Method: http.MethodGet,
		URL:    &url.URL{Path: grid.RouteLockPath},
	}

func guessIsRPCReq(req *http.Request) bool {
	if req == nil {
		return false
	}
	if req.Method == http.MethodGet && req.URL != nil {
		switch req.URL.Path {
		case grid.RoutePath, grid.RouteLockPath:
			return true
		}
	}

	return (req.Method == http.MethodPost || req.Method == http.MethodGet) &&
		strings.HasPrefix(req.URL.Path, minioReservedBucketPath+SlashSeparator)
}