cgr-engine: add flag to print cfg in JSON format

cmd/cgr-engine/cgr-engine.go

@@ -56,6 +56,7 @@ type flags struct {
 	config struct {
 		path    string
 		check   bool
+		print   bool
 		version bool
 	}
 	process struct {
@@ -93,6 +94,7 @@ func newFlags() *flags {
 
 	f.StringVar(&f.config.path, utils.CfgPathCgr, utils.ConfigPath, "Configuration directory path")
 	f.BoolVar(&f.config.check, utils.CheckCfgCgr, false, "Verify the config without starting the engine")
+	f.BoolVar(&f.config.print, utils.PrintCfgCgr, false, "Print configuration object in JSON format")
 	f.BoolVar(&f.config.version, utils.VersionCgr, false, "Print application version and exit")
 
 	f.StringVar(&f.process.pidFile, utils.PidCgr, "", "Path to write the PID file")
@@ -162,6 +164,12 @@ func runCGREngine(fs []string) (err error) {
 		}
 	}
 
+	if flags.config.print {
+		cfgJSON := utils.ToIJSON(cfg.AsMapInterface())
+		utils.Logger.Info(fmt.Sprintf(
+			"Configuration loaded from %q:\n%s", flags.config.path, cfgJSON))
+	}
+
 	var cpuPrfF *os.File
 	if flags.profiling.cpu.dir != utils.EmptyString {
 		cpuPath := filepath.Join(flags.profiling.cpu.dir, utils.CpuPathCgr)

cmd/cgr-engine/flag_test.go

@@ -134,6 +134,13 @@ func TestFlags(t *testing.T) {
 			defaultVal: false,
 			want:       true,
 		},
+		{
+			name:       "print_config",
+			flags:      []string{"-print_config", "true"},
+			flagVar:    &flags.config.print,
+			defaultVal: false,
+			want:       true,
+		},
 		{
 			name:       "set_versions",
 			flags:      []string{"-set_versions"},