fix: Added flags to define buildtime for version command (#344)

* Added flags to define buildtime for version command

* Cleaned ldflag creation

* Added SOURCE DATE EPOCH support for reproducibility

* Removed unneccessary closure and consolidated formatting.

* Minor code formatting changes for builddate

* Simplifying dattime env var logic

Author: Antonio Salinas

magefiles/magebuild/magebuild.go

@@ -11,7 +11,9 @@ import (
 	"os/exec"
 	"path"
 	"regexp"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/magefile/mage/mg"
 	"github.com/magefile/mage/sh"
@@ -34,13 +36,35 @@ var (
 // and folders with test-only code from code coverage calculations.
 var gocovExcludesRegexp = regexp.MustCompile(`(/magefiles/|_test(/|$))`)
 
+// getBuildLdflags returns the ldflags string with build information.
+func getBuildLdflags() (string, error) {
+	buildTime := time.Now().UTC()
+
+	// Check for SOURCE_DATE_EPOCH environment variable for reproducible builds.
+	if epoch := os.Getenv("SOURCE_DATE_EPOCH"); epoch != "" {
+		epochTime, err := strconv.ParseInt(epoch, 10, 64)
+		if err != nil {
+			return "", fmt.Errorf("%#q is an invalid value of the 'SOURCE_DATE_EPOCH' env variable", epoch)
+		}
+
+		buildTime = time.Unix(epochTime, 0).UTC()
+	}
+
+	return fmt.Sprintf(`-X 'go.szostok.io/version.buildDate=%s'`, buildTime.Format(time.RFC3339)), nil
+}
+
 // Build all the go code.
 func Build() error {
 	mg.SerialDeps(checkForBuildErrors, mageutil.CreateBinDir, magesrc.Generate)
 
 	mageutil.MagePrintln(mageutil.MsgStart, "Building...")
 
-	err := sh.Run(mg.GoCmd(), "build", "-o", mageutil.BinDir(), "./...")
+	ldflags, err := getBuildLdflags()
+	if err != nil {
+		return mageutil.PrintAndReturnError("Failed to get build ldflags.", ErrBuild, err)
+	}
+
+	err = sh.Run(mg.GoCmd(), "build", "-ldflags", ldflags, "-o", mageutil.BinDir(), "./...")
 	if err != nil {
 		return mageutil.PrintAndReturnError("Build failed.", ErrBuild, err)
 	}
@@ -56,7 +80,12 @@ func Install() error {
 
 	mageutil.MagePrintln(mageutil.MsgStart, "Installing...")
 
-	err := sh.Run(mg.GoCmd(), "install", "./cmd/azldev")
+	ldflags, err := getBuildLdflags()
+	if err != nil {
+		return mageutil.PrintAndReturnError("Failed to get build ldflags.", ErrInstall, err)
+	}
+
+	err = sh.Run(mg.GoCmd(), "install", "-ldflags", ldflags, "./cmd/azldev")
 	if err != nil {
 		return mageutil.PrintAndReturnError("Install failed.", ErrInstall, err)
 	}