stackedfs

README

stackedfs

stackedfs allows for overlaying different sources to read a file. Think of OverlayFS for Go. It works great with the embed directive and requires at least Go 1.16 because of the fs.FS interface it makes heavy use of.

Install

go get -u github.com/jojomi/stackedfs

Example usage

package main

import (
	"embed"
	"io/fs"
	"os"
	"path/filepath"

	"github.com/kardianos/osext"
	"github.com/rs/zerolog/log"
	"gitlab.com/jojomi/zeiterfassung/stackedfs"
)

//go:embed templates/*
var embeddedTemplates embed.FS

func getTemplateReader() (*stackedfs.StackedFS, error) {
	result := stackedfs.NewStackedFS()

	// add the paths for overwriting the embedded resource files
	paths := getLocalOverwritePaths()
	for _, p := range paths {
		result.AddFS(os.DirFS(filepath.Join(p, "templates")))
	}

	// use the embedded variant as default if nothing else has matched
	subFS, err := fs.Sub(embeddedTemplates, "templates")
	if err != nil {
		return nil, err
	}
	result.AddFS(subFS)

	return result, nil
}

func getLocalOverwritePaths() []string {
	// override paths
	// 1. WORKING_DIR
	// 2. ~/BINARY_NAME/
	// 3. BINARY_DIR

	var (
		binaryName = "stackfs-test"
		folders []string
	)

	workingPath, err := os.Getwd()
	if err != nil {
		log.Fatal().Err(err).Msg("working dir not found")
	}

	home, err := os.UserHomeDir()
	if err != nil {
		log.Fatal().Err(err).Msg("home dir not found")
	}
	homePath := filepath.Join(home, "."+binaryName)

	binaryPath, err := osext.ExecutableFolder()
	if err != nil {
		log.Fatal().Err(err).Msg("binary path not found")
	}

	return append(folders, workingPath, homePath, binaryPath)
}

Documentation

Index

• type StackedFS
  • func NewStackedFS(filesystems ...fs.FS) *StackedFS
  • func (s *StackedFS) AddFS(filesystem fs.FS)
  • func (s *StackedFS) Open(name string) (fs.File, error)

Types

type StackedFS

type StackedFS struct {
	// contains filtered or unexported fields
}

implements fs.FS

func NewStackedFS

func NewStackedFS(filesystems ...fs.FS) *StackedFS

NewStackedFS returns a stacked filesystem. The order is important, a file is returned from the *first* filesystem that does not return an error when queried for the filename.

func (*StackedFS) AddFS

func (s *StackedFS) AddFS(filesystem fs.FS)

func (*StackedFS) Open

func (s *StackedFS) Open(name string) (fs.File, error)