[feat] include git version in generated variable

build.sh

@@ -28,6 +28,7 @@ function init {
 
 function buildGoLib {
     echo "[+] Using go in" $GO "[`go version`]"
+    $GO generate ./pkg/config/version/gen.go
     if [ "$XBUILD" == "no" ]
     then
         echo "[+] Building Go library with standard Go compiler"

pkg/config/version/.gitignore

+version.go

pkg/config/version/LICENSE

+Copyright (c) 2015 Vincent Batts, Raleigh, NC, USA
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

pkg/config/version/gen.go

+package main
+
+//go:generate go run . -output version.go

pkg/config/version/main.go

+package main
+
+import (
+	"flag"
+	"io"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"text/template"
+	"time"
+)
+
+var (
+	flPackageName  = flag.String("package", "main", "name for the generated golang package")
+	flVariableName = flag.String("variable", "VERSION", "variable name in the generated golang package")
+	flOutputFile   = flag.String("output", "", "output filename (default stdout)")
+)
+
+func main() {
+	flag.Parse()
+	dir := "."
+	if flag.NArg() > 0 {
+		dir = flag.Args()[0]
+	}
+	dir, err := filepath.Abs(dir)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var output io.Writer
+	if len(*flOutputFile) > 0 {
+		fh, err := os.Create(*flOutputFile)
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer fh.Close()
+		output = fh
+	} else {
+		output = os.Stdout
+	}
+
+	vers, err := GitDescribe(dir)
+	if err != nil {
+		log.Fatal(err)
+	}
+	vp := VersionPackage{
+		Name:     *flPackageName,
+		Path:     dir,
+		Date:     time.Now(),
+		Variable: *flVariableName,
+		Version:  vers,
+	}
+
+	packageTemplate.Execute(output, vp)
+}
+
+// VersionPackage is the needed information to template a version package
+type VersionPackage struct {
+	Name     string
+	Path     string
+	Date     time.Time
+	Variable string
+	Version  string
+}
+
+var packageTemplate = template.Must(template.New("default").Parse(packageLayout))
+var packageLayout = `package {{.Name}}
+// AUTO-GENERATED. DO NOT EDIT
+// {{.Date}}
+
+// {{.Variable}} is generated by git-describe from gen.go
+var {{.Variable}} = "{{.Version}}"
+ `
+
+// GitDescribe calls `git describe` in the provided path
+func GitDescribe(path string) (string, error) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	// TODO check if this is a directory
+	if err := os.Chdir(path); err != nil {
+		return "", err
+	}
+	defer os.Chdir(cwd)
+
+	buf, err := exec.Command("git", "describe").CombinedOutput()
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(string(buf)), nil
+}