Prevent running as root user

Dockerfile

@@ -5,4 +5,5 @@ RUN go build .
 
 FROM scratch
 COPY --from=builder /source/timetable-mgr /bin/timetable-mgr
+USER nobody
 CMD [ "/bin/timetable-mgr" ]

main.go

@@ -19,9 +19,19 @@ import (
 	"go.uber.org/zap"
 )
 
+const (
+	bold  = "\033[1m"
+	redB  = "\033[1;31m"
+	blue  = "\033[32m" //Actually green!
+	cyan  = "\033[36m"
+	reset = "\033[0m"
+)
+
 func init() {
 	printStartupBanner()
-	fmt.Printf("Version %s \n\n", helpers.Version)
+	fmt.Printf("%sVersion %s \n\n%s", bold+blue, helpers.Version, reset)
+
+	checkRunAsRoot()
 }
 
 func main() {
@@ -110,5 +120,16 @@ func printStartupBanner() {
                                                             |___/      
 	`
 
-	fmt.Println(art)
+	fmt.Println(cyan + art + reset)
+}
+
+func checkRunAsRoot() {
+	uid := os.Getuid()
+	if uid != 0 {
+		return
+	}
+
+	fmt.Println(redB + "This program must not be run as the root user" + reset)
+	fmt.Println("")
+	os.Exit(1)
 }