Also use config from environment

main.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"os/signal"
 	"path"
+	"strconv"
 	"strings"
 	"syscall"
 )
@@ -65,7 +66,7 @@ func StripPrefix(prefix string, h http.Handler) http.Handler {
 func main() {
 	var bind = flag.String("bind", "127.0.0.1:8080", "Bind port/socket")
 	var baseURL = flag.String("baseurl", "/", "URL prepended to each URL")
-	var configfile = flag.String("config", "config.json", "path to the configuration file")
+	var configfile = flag.String("config", "", "path to the configuration file")
 	flag.Parse()
 
 	// Sanitize options
@@ -79,6 +80,7 @@ func main() {
 	}
 
 	// Load config file
+	if configfile != nil && *configfile != "" {
 		if fd, err := os.Open(*configfile); err != nil {
 			log.Fatal(err)
 		} else if cnt, err := ioutil.ReadAll(fd); err != nil {
@@ -86,6 +88,42 @@ func main() {
 		} else if err := json.Unmarshal(cnt, &myLDAP); err != nil {
 			log.Fatal(err)
 		}
+	}
+
+	// Read configuration from environment
+	if val, ok := os.LookupEnv("LDAP_HOST"); ok {
+		myLDAP.Host = val
+	}
+	if val, ok := os.LookupEnv("LDAP_PORT"); ok {
+		if port, err := strconv.Atoi(val); err == nil {
+			myLDAP.Port = port
+		} else {
+			log.Println("Invalid value for LDAP_PORT:", val)
+		}
+	}
+	if val, ok := os.LookupEnv("LDAP_STARTTLS"); ok {
+		myLDAP.Starttls = val == "1" || val == "on" || val == "true"
+	}
+	if val, ok := os.LookupEnv("LDAP_SSL"); ok {
+		myLDAP.Ssl = val == "1" || val == "on" || val == "true"
+	}
+	if val, ok := os.LookupEnv("LDAP_BASEDN"); ok {
+		myLDAP.BaseDN = val
+	}
+	if val, ok := os.LookupEnv("LDAP_SERVICEDN"); ok {
+		myLDAP.ServiceDN = val
+	}
+	if val, ok := os.LookupEnv("LDAP_SERVICE_PASSWORD_FILE"); ok {
+		if fd, err := os.Open(val); err != nil {
+			log.Fatal(err)
+		} else if cnt, err := ioutil.ReadAll(fd); err != nil {
+			log.Fatal(err)
+		} else {
+			myLDAP.ServicePassword = string(cnt)
+		}
+	} else if val, ok := os.LookupEnv("LDAP_SERVICE_PASSWORD"); ok {
+		myLDAP.ServicePassword = val
+	}
 
 	// Prepare graceful shutdown
 	interrupt := make(chan os.Signal, 1)