cmd: Prevent overwriting existing env vars with --envfile (#5803)

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

cmd/commandfuncs.go

@@ -46,7 +46,14 @@ func cmdStart(fl Flags) (int, error) {
 	startCmdConfigAdapterFlag := fl.String("adapter")
 	startCmdPidfileFlag := fl.String("pidfile")
 	startCmdWatchFlag := fl.Bool("watch")
-	startCmdEnvfileFlag := fl.String("envfile")
+
+	var err error
+	var startCmdEnvfileFlag []string
+	startCmdEnvfileFlag, err = fl.GetStringSlice("envfile")
+	if err != nil {
+		return caddy.ExitCodeFailedStartup,
+			fmt.Errorf("reading envfile flag: %v", err)
+	}
 
 	// open a listener to which the child process will connect when
 	// it is ready to confirm that it has successfully started
@@ -70,8 +77,9 @@ func cmdStart(fl Flags) (int, error) {
 	if startCmdConfigFlag != "" {
 		cmd.Args = append(cmd.Args, "--config", startCmdConfigFlag)
 	}
-	if startCmdEnvfileFlag != "" {
+
-		cmd.Args = append(cmd.Args, "--envfile", startCmdEnvfileFlag)
+	for _, envFile := range startCmdEnvfileFlag {
+		cmd.Args = append(cmd.Args, "--envfile", envFile)
 	}
 	if startCmdConfigAdapterFlag != "" {
 		cmd.Args = append(cmd.Args, "--adapter", startCmdConfigAdapterFlag)
@@ -160,15 +168,22 @@ func cmdRun(fl Flags) (int, error) {
 	runCmdConfigFlag := fl.String("config")
 	runCmdConfigAdapterFlag := fl.String("adapter")
 	runCmdResumeFlag := fl.Bool("resume")
-	runCmdLoadEnvfileFlag := fl.String("envfile")
 	runCmdPrintEnvFlag := fl.Bool("environ")
 	runCmdWatchFlag := fl.Bool("watch")
 	runCmdPidfileFlag := fl.String("pidfile")
 	runCmdPingbackFlag := fl.String("pingback")
 
+	var err error
+	var runCmdLoadEnvfileFlag []string
+	runCmdLoadEnvfileFlag, err = fl.GetStringSlice("envfile")
+	if err != nil {
+		return caddy.ExitCodeFailedStartup,
+			fmt.Errorf("reading envfile flag: %v", err)
+	}
+
 	// load all additional envs as soon as possible
-	if runCmdLoadEnvfileFlag != "" {
+	for _, envFile := range runCmdLoadEnvfileFlag {
-		if err := loadEnvFromFile(runCmdLoadEnvfileFlag); err != nil {
+		if err := loadEnvFromFile(envFile); err != nil {
 			return caddy.ExitCodeFailedStartup,
 				fmt.Errorf("loading additional environment variables: %v", err)
 		}
@@ -181,7 +196,6 @@ func cmdRun(fl Flags) (int, error) {
 
 	// load the config, depending on flags
 	var config []byte
-	var err error
 	if runCmdResumeFlag {
 		config, err = os.ReadFile(caddy.ConfigAutosavePath)
 		if os.IsNotExist(err) {
@@ -497,18 +511,24 @@ func cmdAdaptConfig(fl Flags) (int, error) {
 func cmdValidateConfig(fl Flags) (int, error) {
 	validateCmdConfigFlag := fl.String("config")
 	validateCmdAdapterFlag := fl.String("adapter")
-	runCmdLoadEnvfileFlag := fl.String("envfile")
+
+	var err error
+	var runCmdLoadEnvfileFlag []string
+	runCmdLoadEnvfileFlag, err = fl.GetStringSlice("envfile")
+	if err != nil {
+		return caddy.ExitCodeFailedStartup,
+			fmt.Errorf("reading envfile flag: %v", err)
+	}
 
 	// load all additional envs as soon as possible
-	if runCmdLoadEnvfileFlag != "" {
+	for _, envFile := range runCmdLoadEnvfileFlag {
-		if err := loadEnvFromFile(runCmdLoadEnvfileFlag); err != nil {
+		if err := loadEnvFromFile(envFile); err != nil {
 			return caddy.ExitCodeFailedStartup,
 				fmt.Errorf("loading additional environment variables: %v", err)
 		}
 	}
 
 	// use default config and ensure a config file is specified
-	var err error
 	validateCmdConfigFlag, err = configFileWithRespectToDefault(caddy.Log(), validateCmdConfigFlag)
 	if err != nil {
 		return caddy.ExitCodeFailedStartup, err

cmd/commands.go

@@ -104,7 +104,7 @@ using 'caddy run' instead to keep it in the foreground.
 		CobraFunc: func(cmd *cobra.Command) {
 			cmd.Flags().StringP("config", "c", "", "Configuration file")
 			cmd.Flags().StringP("adapter", "a", "", "Name of config adapter to apply")
-			cmd.Flags().StringP("envfile", "", "", "Environment file to load")
+			cmd.Flags().StringSliceP("envfile", "", []string{}, "Environment file(s) to load")
 			cmd.Flags().BoolP("watch", "w", false, "Reload changed config file automatically")
 			cmd.Flags().StringP("pidfile", "", "", "Path of file to which to write process ID")
 			cmd.RunE = WrapCommandFuncForCobra(cmdStart)
@@ -150,7 +150,7 @@ option in a local development environment.
 		CobraFunc: func(cmd *cobra.Command) {
 			cmd.Flags().StringP("config", "c", "", "Configuration file")
 			cmd.Flags().StringP("adapter", "a", "", "Name of config adapter to apply")
-			cmd.Flags().StringP("envfile", "", "", "Environment file to load")
+			cmd.Flags().StringSliceP("envfile", "", []string{}, "Environment file(s) to load")
 			cmd.Flags().BoolP("environ", "e", false, "Print environment")
 			cmd.Flags().BoolP("resume", "r", false, "Use saved config, if any (and prefer over --config file)")
 			cmd.Flags().BoolP("watch", "w", false, "Watch config file for changes and reload it automatically")
@@ -301,7 +301,7 @@ the KEY=VALUE format will be loaded into the Caddy process.
 		CobraFunc: func(cmd *cobra.Command) {
 			cmd.Flags().StringP("config", "c", "", "Input configuration file")
 			cmd.Flags().StringP("adapter", "a", "", "Name of config adapter")
-			cmd.Flags().StringP("envfile", "", "", "Environment file to load")
+			cmd.Flags().StringSliceP("envfile", "", []string{}, "Environment file(s) to load")
 			cmd.RunE = WrapCommandFuncForCobra(cmdValidateConfig)
 		},
 	})

cmd/main.go

@@ -300,8 +300,12 @@ func loadEnvFromFile(envFile string) error {
 	}
 
 	for k, v := range envMap {
-		if err := os.Setenv(k, v); err != nil {
+		// do not overwrite existing environment variables
-			return fmt.Errorf("setting environment variables: %v", err)
+		_, exists := os.LookupEnv(k)
+		if !exists {
+			if err := os.Setenv(k, v); err != nil {
+				return fmt.Errorf("setting environment variables: %v", err)
+			}
 		}
 	}