Go filesystem implementations for various URL schemes

hairyhenderson/go-fsimpl

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This module contains a collection of Go filesystem implementations that can discovered dynamically by URL scheme. All filesystems are read-only.

These filesystems implement the fs.FS interface introduced in Go 1.16

Most implementations implement the fs.ReadDirFS interface, though the https filesystem does not.

Some extensions are available to help add specific functionality to certain filesystems:

  • WithContextFS – injects a context into a filesystem, for propagating cancellation in filesystems that support it.
  • WithHeaderFS – sets the http.Header for all HTTP requests used by the filesystem. This can be useful for authentication, or for requesting specific content types.
  • WithHTTPClientFS – sets the *http.Client for all HTTP requests to be made with.

This module also provides ContentType, an extension to the fs.FileInfo type to help identify an appropriate MIME content type for a given file. For filesystems that support it, the HTTP Content-Type header is used for this. Otherwise, the type is guessed from the file extension.

History & Project Status

This module is in development, and the API is still subject to change. The filesystems that are supported should operate correctly.

Most of these filesystems are based on code from gomplate, which supports all of these as datasources. This module is intended to eventually be used within gomplate.

Supported Filesystems

Here’s the list of planned filesystem support, along with status:

Scheme(s) Description Supported?
aws+sm AWS Secrets Manager
aws+smp AWS Systems Manager Parameter Store
azblob Azure Blob Storage

consul, consul+http, consul+https HashiCorp Consul
file local filesystem

git, git+file, git+http, git+https, git+ssh local/remote git repository

gs Google Cloud Storage

http, https HTTP server

s3 Amazon S3

vault, vault+http, vault+https HashiCorp Vault

See url_schemes.md for more details on each scheme.

Installation

You need Go 1.16 or above to use this module. Use go get to install the latest version of go-fsimpl:

$ go get -u github.com/hairyhenderson/go-fsimpl

Usage

If you know that you want an HTTP filesystem, for example:

import (
	"net/url"

	"github.com/hairyhenderson/go-fsimpl/httpfs"
)

func main() {
	base, _ := url.Parse("https://example.com")
	fsys, _ := httpfs.New(base)

	f, _ := fsys.Open("hello.txt")
	defer f.Close()

	// now do what you like with the file...
}

If you’re not sure what filesystem type you need (for example, if you’re dealing with a user-provided URL), you can use a filesystem mux:

import (
	"github.com/hairyhenderson/go-fsimpl"
	"github.com/hairyhenderson/go-fsimpl/blobfs"
	"github.com/hairyhenderson/go-fsimpl/filefs"
	"github.com/hairyhenderson/go-fsimpl/gitfs"
	"github.com/hairyhenderson/go-fsimpl/httpfs"
)

func main() {
	mux := fsimpl.NewMux()
	mux.Add(filefs.FS)
	mux.Add(httpfs.FS)
	mux.Add(blobfs.FS)
	mux.Add(gitfs.FS)

	// for example, a URL that points to a subdirectory at a specific tag in a
	// given git repo, hosted on GitHub and authenticated with SSH...
	fsys, err := mux.Lookup("git+ssh://[email protected]/foo/bar.git//baz#refs/tags/v1.0.0")
	if err != nil {
		log.Fatal(err)
	}

	f, _ := fsys.Open("hello.txt")
	defer f.Close()

	// now do what you like with the file...
}

License

The MIT License

Copyright (c) 2021 Dave Henderson

GitHub

https://github.com/hairyhenderson/go-fsimpl

Go filesystem implementations for various URL schemes