revhttpfs

RevHttpFs

The afero golang library already has an afero.HttpFs which goes from an afero Fs to http.FileSystem. This package implements the reverse, allowing use of an http.FileSystem as an afero.Fs.

Motivation

The reason for this is that many tools expose http.FileSystem interfaces, since it is the standard in golang for serving files.

In particular, tools to embed files in golang executables usually return http.FileSystems (see statik, packr, vfsgen, etc).

Allowing to use these with Afero leads to some really useful stuff, such as using afero.CopyOnWriteFs to "overlay" a configuration folder/memory map over the http.FileSystem returned from such tools.

Example

import (

    "github.com/rakyll/statik/fs"
    "github.com/spf13/afero"
    "github.com/dkumor/revhttpfs"
)

func OverwritableBuiltinFileSystem() (afero.Fs,error) {
    statikFS, err := fs.New()
    if err!=nil {
        return nil,err
    }

    aferoStatikFs := revhttpfs.NewReverseHttpFs(statikFS)
    overwritableStatikFs := afero.NewMemMapFs()

    return afero.NewCopyOnWriteFs(aferoStatikFs, pluginFs),nil
}

The above code uses resources embedded in the executable with statik, which come in the form of an http.FileSystem, uses ReverseHttpFs to convert it to an afero.Fs, and then creates a copy-on-write overlay over the static built-in files, using a memory map.