Packr is a simple solution for bundling static assets inside of Go binaries. Most importantly it does it in a way that is friendly to developers while they are developing.
$ go get -u github.com/gobuffalo/packr/...
The first step in using Packr is to create a new box. A box represents a folder on disk. Once you have a box you can get string or []byte representations of the file.
// set up a new box by giving it a path to a
// folder on disk:
box := packr.NewBox("./templates")
// Get the string representation of a file:
html := box.String("index.html")
// Get the string representation of a file, or an error if it doesn't exist:
html, err := box.MustString("index.html")
// Get the []byte representation of a file:
html := box.Bytes("index.html")
// Get the []byte representation of a file, or an error if it doesn't exist:
html, err := box.MustBytes("index.html")When it comes time to build, or install, your Go binary, simply use packr build or packr install just as you would go build or go install. All flags for the go tool are supported and everything works the way you expect, the only difference is your static assets are now bundled in the generated binary. If you want more control over how this happens, looking at the following section on building binaries (the hard way).
Before you build your Go binary, run the packr command first. It will look for all the boxes in your code and then generate .go files that pack the static files into bytes that can be bundled into the Go binary.
$ packr
--> packing foo/foo-packr.go
--> packing example-packr.go
Then run your go build command like normal.
When you're done it is recommended that you run the packr clean command. This will remove all of the generated files that Packr created for you.
$ packr clean
----> cleaning up example-packr.go
----> cleaning up foo/foo-packr.go
Why do you want to do this? Packr first looks to the information stored in these generated files, if the information isn't there it looks to disk. This makes it easy to work with in development.