go-billy 
The missing interface filesystem abstraction for Go.
Billy implements an interface based on the os standard library, allowing to develop applications without dependency on the underlying storage. Makes it virtually free to implement mocks and testing over filesystem operations.
Billy was born as part of go-git/go-git project.
Installation
import "github.com/go-git/go-billy/v5" // with go modules enabled (GO111MODULE=on or outside GOPATH)
import "github.com/go-git/go-billy" // with go modules disabledUsage
Billy exposes filesystems using the
Filesystem interface.
Each filesystem implementation gives you a New method, whose arguments depend on
the implementation itself, that returns a new Filesystem.
The following example caches in memory all readable files in a directory from any billy's filesystem implementation.
func LoadToMemory(origin billy.Filesystem, path string) (*memory.Memory, error) {
memory := memory.New()
files, err := origin.ReadDir("/")
if err != nil {
return nil, err
}
for _, file := range files {
if file.IsDir() {
continue
}
src, err := origin.Open(file.Name())
if err != nil {
return nil, err
}
dst, err := memory.Create(file.Name())
if err != nil {
return nil, err
}
if _, err = io.Copy(dst, src); err != nil {
return nil, err
}
if err := dst.Close(); err != nil {
return nil, err
}
if err := src.Close(); err != nil {
return nil, err
}
}
return memory, nil
}Why billy?
The library billy deals with storage systems and Billy is the name of a well-known, IKEA bookcase. That's it.
License
Apache License Version 2.0, see LICENSE