Add --version flag to get version and build information (#11)

Author: ChappIO

.github/workflows/build.yml

@@ -42,7 +42,7 @@ jobs:
       - uses: actions/setup-go@v2
         with:
           go-version: '^1.17.8'
-      - run: ${{ matrix.goopts }} go build -o ${{ matrix.filename }} ./cmd/git-backup
+      - run: ${{ matrix.goopts }} go build -o ${{ matrix.filename }} -ldflags="-X 'main.Version=${GITHUB_REF##*/}' -X 'main.CommitHash=${GITHUB_SHA}' -X 'main.BuildTimestamp=$(date)'" ./cmd/git-backup
         env:
           GOOS: ${{ matrix.goos }}
           GOARCH: ${{ matrix.goarch }}

README.md

@@ -79,7 +79,9 @@ Options:
   -backup.fail-at-end
       Fail at the end of backing up repositories, rather than right away.
   -backup.bare-clone
-        Make bare clones without checking out the main branch.
+      Make bare clones without checking out the main branch.
+  -version
+      Show the version number and exit.
 ```
 
 ## Usage: Docker

cmd/git-backup/main.go

@@ -6,17 +6,29 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"runtime"
 	"time"
 )
 
 var configFilePath = flag.String("config.file", "git-backup.yml", "The path to your config file.")
 var targetPath = flag.String("backup.path", "backup", "The target path to the backup folder.")
 var failAtEnd = flag.Bool("backup.fail-at-end", false, "Fail at the end of backing up repositories, rather than right away.")
 var bareClone = flag.Bool("backup.bare-clone", false, "Make bare clones without checking out the main branch.")
+var printVersion = flag.Bool("version", false, "Show the version number and exit.")
+
+var Version = "dev"
+var CommitHash = "n/a"
+var BuildTimestamp = "n/a"
 
 func main() {
 	flag.Parse()
 
+	if *printVersion {
+		log.Printf("git-backup, version %s (%s-%s)", Version, runtime.GOOS, runtime.GOARCH)
+		log.Printf("Built %s (%s)", CommitHash, BuildTimestamp)
+		os.Exit(0)
+	}
+
 	config := loadConfig()
 	sources := config.GetSources()
 	if len(sources) == 0 {