Go resource embedding library which doesn't require go generate at all.
Resource Embedding in Go is cumbersome especially when it involves custom commands and go generate.
assets is another resource embedding library which doesn't require any of them.
It extracts a zip file bundled with your binary and provides a file path to the contents.
- no custom commands
- no
go generate - only requires
catandzipwhengo build - uses local files when
go runorgo test - easily extendable interface
We assume you have a Go project and a directory named assets for resources in the project root.
This directory name can be easily configured but for the sake of explanation we call the directory assets.
$ tree .
.
├── Makefile
├── assets
│ └── templates
│ └── hello.tmpl
└── main.go
2 directories, 3 files
First go get the library.
$ go get github.com/ichiban/assetsThen import it.
import "github.com/ichiban/assets"
In Go files, we can get the locator which points to assets directory by calling assets.New().
Note that we'll need to close it in the end.
l, err := assets.New()
if err != nil {
log.Fatalf("assets.New() failed: %v", err)
}
defer l.Close()
log.Printf("assets: %s", l.Path)When we build it and bundle with a resource zip file, the locator will point to the contents of the zip file which is extracted into a temporary directory.
To start with, we need to build the binary as usual.
$ mkdir -p bin
$ go build -o bin/hello
Then, zip resources into a zip file.
We need to enter assets directory to make a proper zip file.
$ mkdir -p zip
$ cd assets
$ zip -r ../zip/assets.zip .
adding: templates/ (stored 0%)
adding: templates/hello.tmpl (stored 0%)
$ cd ..
A proper zip file looks like this:
$ unzip -l zip/assets.zip
Archive: zip/assets.zip
Length Date Time Name
--------- ---------- ----- ----
0 11-05-2018 22:31 templates/
14 11-05-2018 21:31 templates/hello.tmpl
--------- -------
14 2 files
Finally, we can bundle resources by cat the binary and the zip file.
Prepending an executable makes the zip offset values off by the size of the executable.
We can fix the offsets by zip -A (zip --adjust-sfx).
$ cat bin/hello zip/assets.zip > bin/hello-bundled
$ zip -A bin/hello-bundled
Zip entry offsets appear off by 3345496 bytes - correcting...
$ chmod +x bin/hello-bundled
Interestingly, the bundled binary is an executable and also a zip file.
$ unzip -l bin/hello-bundled
Archive: bin/hello-bundled
Length Date Time Name
--------- ---------- ----- ----
0 11-05-2018 22:31 templates/
14 11-05-2018 21:31 templates/hello.tmpl
--------- -------
14 2 files
$ bin/hello-bundled
2018/11/30 16:22:13 assets: /var/folders/xt/6z9sk1dx1d734ltxxst16_h00000gn/T/hello-bundled882816570
Hello, World!
This project is licensed under the MIT License - see the LICENSE.md file for details.
This project is inspired by Zgok.