pkger

package module
Version: v0.17.1 Latest Latest
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Published: Aug 12, 2020 License: MIT Imports: 7 Imported by: 262

README

Pkger

github.com/markbates/pkger is a tool for embedding static files into Go binaries. It will, hopefully, be a replacement for github.com/gobuffalo/packr/v2.

Requirements
  • Go 1.13+
  • Go Modules

How it Works (Module Aware Pathing)

Pkger is powered by the dark magic of Go Modules, so they're like, totally required.

With Go Modules pkger can resolve packages with accuracy. No more guessing and trying to figure out build paths, GOPATHS, etc... for this tired old lad.

With the module's path correctly resolved, it can serve as the "root" directory for that module, and all files in that module's directory are available.

Paths:

  • Paths should use UNIX style paths: /cmd/pkger/main.go
  • If unspecified the path's package is assumed to be the current module.
  • Packages can specified in at the beginning of a path with a : seperator. github.com/markbates/pkger:/cmd/pkger/main.go
  • There are no relative paths. All paths are absolute to the modules root.
  • Fully-qualified paths are embedded into the metadata of your static assets. If this behavior is undesirable, a preference is to build in a containerized environ, like docker, where the path strings are not ex-filtrating data about your development environment.
"github.com/gobuffalo/buffalo:/go.mod" => /go/pkg/mod/github.com/gobuffalo/buffalo@v0.14.7/go.mod

CLI

Installation
$ go get github.com/markbates/pkger/cmd/pkger
$ pkger -h
Usage
$ pkger

The result will be a pkged.go file in the root of the module with the embedded information and the package name of the module.

// ./pkged.go
package <.>

// Pkger stuff here

The -o flag can be used to specify the directory of the pkged.go file.

$ pkger -o cmd/reader

The result will be a pkged.go file in the cmd/reader folder with the embedded information and the package name of that folder.

// cmd/reader/pkged.go
package <reader>

// Pkger stuff here
Including Files at Package Time

There may be reasons where you don't reference a particular file, or folder, that you want embedded in your application, such as a build artifact.

To do this you may use either the github.com/markbates/pkger#Include function to set a no-op parser directive to include the specified path.

Alternatively, you may use the -include flag with the pkger and pkger list commands.

$ pkger list -include /actions -include github.com/gobuffalo/buffalo:/app.go

app
 > app:/actions
 > app:/actions/actions.go
 > app:/assets
 > app:/assets/css
 > app:/assets/css/_buffalo.scss
 > app:/assets/css/application.scss
 > app:/assets/images
 > app:/assets/images/favicon.ico
 > app:/assets/images/logo.svg
 > app:/assets/js
 > app:/assets/js/application.js
 > app:/go.mod
 > app:/locales/all.en-us.yaml
 > app:/public
 > app:/public/assets
 > app:/public/assets/.keep
 > app:/public/assets/app.css
 > app:/public/images
 > app:/public/images/img1.png
 > app:/public/index.html
 > app:/public/robots.txt
 > app:/templates
 > app:/templates/_flash.plush.html
 > app:/templates/application.plush.html
 > app:/templates/index.plush.html
 > app:/web
 > app:/web/web.go
 > github.com/gobuffalo/buffalo:/app.go
 > github.com/gobuffalo/buffalo:/logo.svg

Reference Application

The reference application for the README examples, as well as all testing, can be found at https://github.com/markbates/pkger/tree/master/pkging/pkgtest/testdata/ref.

├── actions
│   └── actions.go
├── assets
│   ├── css
│   │   ├── _buffalo.scss
│   │   └── application.scss
│   ├── images
│   │   ├── favicon.ico
│   │   └── logo.svg
│   └── js
│       └── application.js
├── go.mod
├── go.sum
├── locales
│   └── all.en-us.yaml
├── main.go
├── mod
│   └── mod.go
├── models
│   └── models.go
├── public
│   ├── assets
│   │   └── app.css
│   ├── images
│   │   └── img1.png
│   ├── index.html
│   └── robots.txt
├── templates
│   ├── _flash.plush.html
│   ├── application.plush.html
│   └── index.plush.html
└── web
    └── web.go

13 directories, 20 files

API Usage

Pkger's API is modeled on that of the os package in Go's standard library. This makes Pkger usage familiar to Go developers.

The two most important interfaces are github.com/markbates/pkger/pkging#Pkger and github.com/markbates/pkger/pkging#File.

type Pkger interface {
  Parse(p string) (Path, error)
  Current() (here.Info, error)
  Info(p string) (here.Info, error)
  Create(name string) (File, error)
  MkdirAll(p string, perm os.FileMode) error
  Open(name string) (File, error)
  Stat(name string) (os.FileInfo, error)
  Walk(p string, wf filepath.WalkFunc) error
  Remove(name string) error
  RemoveAll(path string) error
}

type File interface {
  Close() error
  Info() here.Info
  Name() string
  Open(name string) (http.File, error)
  Path() Path
  Read(p []byte) (int, error)
  Readdir(count int) ([]os.FileInfo, error)
  Seek(offset int64, whence int) (int64, error)
  Stat() (os.FileInfo, error)
  Write(b []byte) (int, error)
}

These two interfaces, along with the os#FileInfo, provide the bulk of the API surface area.

Open
func run() error {
	f, err := pkger.Open("/public/index.html")
	if err != nil {
		return err
	}
	defer f.Close()

	info, err := f.Stat()
	if err != nil {
		return err
	}

	fmt.Println("Name: ", info.Name())
	fmt.Println("Size: ", info.Size())
	fmt.Println("Mode: ", info.Mode())
	fmt.Println("ModTime: ", info.ModTime())

	if _, err := io.Copy(os.Stdout, f); err != nil {
		return err
	}
	return nil
}
Stat
func run() error {
	info, err := pkger.Stat("/public/index.html")
	if err != nil {
		return err
	}

	fmt.Println("Name: ", info.Name())
	fmt.Println("Size: ", info.Size())
	fmt.Println("Mode: ", info.Mode())
	fmt.Println("ModTime: ", info.ModTime())

	return nil
}
Walk
func run() error {
	w := tabwriter.NewWriter(os.Stdout, 0, 0, 0, ' ', tabwriter.Debug)
	defer w.Flush()

	return pkger.Walk("/public", func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		fmt.Fprintf(w,
			"%s \t %d \t %s \t %s \t\n",
			info.Name(),
			info.Size(),
			info.Mode(),
			info.ModTime().Format(time.RFC3339),
		)

		return nil
	})

}

Understanding the Parser

The github.com/markbates/pkger/parser#Parser works by statically analyzing the source code of your module using the go/parser to find a selection of declarations.

The following declarations in your source code will tell the parser to embed files or folders.

  • pkger.Dir("<path>") - Embeds all files under the specified path.
  • pkger.Open("<path>") - Embeds the file, or folder, of the specified path.
  • pkger.Stat("<path>") - Embeds the file, or folder, of the specified path.
  • pkger.Walk("<path>", filepath.WalkFunc) - Embeds all files under the specified path.
  • pkger.Include("<path>") - Include is a no-op that directs the pkger tool to include the desired file or folder.
CLI Usage

To see what declarations the parser has found, you can use the pkger parse command to get a JSON list of the declarations.

$ pkger parse

{
 ".": [
  {
   "file": {
    "Abs": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/foo/bar/baz",
    "Path": {
     "Pkg": "app",
     "Name": "/foo/bar/baz"
    },
    "Here": {
     "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
     "ImportPath": "app",
     "Module": {
      "Path": "app",
      "Main": true,
      "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
      "GoMod": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/go.mod",
      "GoVersion": "1.13"
     },
     "Name": "main"
    }
   },
   "pos": {
    "Filename": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/main.go",
    "Offset": 629,
    "Line": 47,
    "Column": 27
   },
   "type": "pkger.MkdirAll",
   "value": "/foo/bar/baz"
  },
  {
   "file": {
    "Abs": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/foo/bar/baz/biz.txt",
    "Path": {
     "Pkg": "app",
     "Name": "/foo/bar/baz/biz.txt"
    },
    "Here": {
     "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
     "ImportPath": "app",
     "Module": {
      "Path": "app",
      "Main": true,
      "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
      "GoMod": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/go.mod",
      "GoVersion": "1.13"
     },
     "Name": "main"
    }
   },
   "pos": {
    "Filename": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/main.go",
    "Offset": 706,
    "Line": 51,
    "Column": 25
   },
   "type": "pkger.Create",
   "value": "/foo/bar/baz/biz.txt"
  },
  ...
 ]
}

For a module aware list use the pkger list command.

$ pkger list

app
 > app:/assets
 > app:/assets/css
 > app:/assets/css/_buffalo.scss
 > app:/assets/css/application.scss
 > app:/assets/images
 > app:/assets/images/favicon.ico
 > app:/assets/images/logo.svg
 > app:/assets/js
 > app:/assets/js/application.js
 > app:/go.mod
 > app:/locales/all.en-us.yaml
 > app:/public
 > app:/public/assets
 > app:/public/assets/.keep
 > app:/public/assets/app.css
 > app:/public/images
 > app:/public/images/img1.png
 > app:/public/index.html
 > app:/public/robots.txt
 > app:/templates
 > app:/templates/_flash.plush.html
 > app:/templates/application.plush.html
 > app:/templates/index.plush.html
 > app:/web
 > app:/web/web.go
 > github.com/gobuffalo/buffalo:/logo.svg

The -json flag can be used to get a more detailed list in JSON.

$ pkger list -json

{
 "ImportPath": "app",
 "Files": [
  {
   "Abs": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/assets",
   "Path": {
    "Pkg": "app",
    "Name": "/assets"
   },
   "Here": {
    "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/assets",
    "ImportPath": "",
    "Module": {
     "Path": "app",
     "Main": true,
     "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
     "GoMod": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/go.mod",
     "GoVersion": "1.13"
    },
    "Name": "assets"
   }
  },
  {
   "Abs": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/assets/css",
   "Path": {
    "Pkg": "app",
    "Name": "/assets/css"
   },
   "Here": {
    "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/assets",
    "ImportPath": "",
    "Module": {
     "Path": "app",
     "Main": true,
     "Dir": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref",
     "GoMod": "/go/src/github.com/markbates/pkger/pkging/pkgtest/testdata/ref/go.mod",
     "GoVersion": "1.13"
    },
    "Name": "assets"
   }
  },
  ...
}

Documentation

Index

Constants

This section is empty.

Variables

View Source
var Version = "development"

Version of pkger

Functions

func Apply

func Apply(pkg pkging.Pkger, err error) error

Apply will wrap the current implementation of pkger.Pkger with the new pkg. This allows for layering of pkging.Pkger implementations.

func Create

func Create(p string) (pkging.File, error)

Create creates the named file with mode 0666 (before umask) - It's actually 0644, truncating it if it already exists. If successful, methods on the returned File can be used for I/O; the associated file descriptor has mode O_RDWR.

func Current

func Current() (here.Info, error)

Current returns the here.Info representing the current Pkger implementation.

func Include added in v0.12.0

func Include(name string) string

Include is a no-op that directs the pkger tool to include the desired file or folder.

func Info

func Info(p string) (here.Info, error)

Info returns the here.Info of the here.Path

func MkdirAll

func MkdirAll(p string, perm os.FileMode) error

MkdirAll creates a directory named path, along with any necessary parents, and returns nil, or else returns an error. The permission bits perm (before umask) are used for all directories that MkdirAll creates. If path is already a directory, MkdirAll does nothing and returns nil.

func Open

func Open(p string) (pkging.File, error)

Open opens the named file for reading. If successful, methods on the returned file can be used for reading; the associated file descriptor has mode O_RDONLY.

func Parse

func Parse(p string) (here.Path, error)

Parse the string in here.Path format.

func Remove

func Remove(name string) error

Remove removes the named file or (empty) directory.

func RemoveAll

func RemoveAll(name string) error

RemoveAll removes path and any children it contains. It removes everything it can but returns the first error it encounters. If the path does not exist, RemoveAll returns nil (no error).

func Stat

func Stat(name string) (os.FileInfo, error)

Stat returns a FileInfo describing the named file.

func Walk

func Walk(p string, wf filepath.WalkFunc) error

Walk walks the file tree rooted at root, calling walkFn for each file or directory in the tree, including root. All errors that arise visiting files and directories are filtered by walkFn. The files are walked in lexical order, which makes the output deterministic but means that for very large directories Walk can be inefficient. Walk does not follow symbolic links. - That is from the standard library. I know. Their grammar teachers can not be happy with them right now.

Types

type Dir added in v0.7.0

type Dir string

func (Dir) Open added in v0.7.0

func (d Dir) Open(name string) (http.File, error)

Directories

Path Synopsis
cmd
examples
app Module
complex Module
extfile Module
httpserver Module
walk Module
mem
internal
examples/app Module
examples/walk Module

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