Add support for configuring the logger via environment variables

env.go

@@ -0,0 +1,29 @@
+package logger
+
+import (
+	"os"
+	"strings"
+)
+
+// getEnvBool returns a boolean value read from the environmnet variable.
+// If the variable was not set, the default value will be returned
+func getEnvBool(name string, defaultValue bool) bool {
+	val := defaultValue
+	if strVal, isSet := os.LookupEnv(name); isSet {
+		strVal = strings.ToLower(strVal)
+		return strVal == "1" || strVal == "true" || strVal == "yes" || strVal == "ja"
+	}
+
+	return val
+}
+
+// getEnvString returns a string value read from the environmnet variable.
+// If the variable was not set, the default value will be returned
+func getEnvString(name string, defaultValue string) string {
+	val := defaultValue
+	if strVal, isSet := os.LookupEnv(name); isSet {
+		val = strVal
+	}
+
+	return val
+}

level.go

@@ -0,0 +1,62 @@
+package logger
+
+import "strings"
+
+// Level of the log message
+type Level uint8
+
+const (
+	LevelTrace Level = iota
+	LevelDebug
+	LevelInfo
+	LevelWarning
+	LevelError
+	LevelFatal
+)
+
+// String returns a string expression of the level
+func (lvl Level) String() string {
+	switch lvl {
+	case LevelTrace:
+		return "TRACE"
+	case LevelDebug:
+		return "DEBUG"
+	case LevelInfo:
+		return "INFO"
+	case LevelWarning:
+		return "WARNING"
+	case LevelError:
+		return "ERROR"
+	case LevelFatal:
+		return "FATAL"
+	}
+
+	return "DEBUG"
+}
+
+// GetLevelByName tries to convert the given level name to the represented level code.
+// Allowed values are: 'trace', 'debug', 'info', 'warn', 'warning', 'error', 'panic' and 'fatal'
+// If an incorrect level name was given a warning is logged and info will be returned
+func GetLevelByName(levelName string) Level {
+	levelName = strings.ToLower(levelName)
+	switch levelName {
+	case "trace":
+		return LevelTrace
+	case "debug":
+		return LevelDebug
+	case "info":
+		return LevelInfo
+	case "warn", "warning":
+		return LevelWarning
+	case "error":
+		return LevelError
+	case "panic", "fatal":
+		return LevelFatal
+
+	default:
+		{
+			Warning("Unable to parse the level name '%s'. Expected 'debug', 'info', 'warn', 'error' or 'fatal'", levelName)
+			return LevelWarning
+		}
+	}
+}

logger.go

@@ -12,18 +12,6 @@ import (
 	"time"
 )
 
-// Level of the log message
-type Level uint8
-
-const (
-	LevelTrace Level = iota
-	LevelDebug
-	LevelInfo
-	LevelWarning
-	LevelError
-	LevelFatal
-)
-
 type Logger struct {
 	PrintLevel  Level
 	LogLevel    Level
@@ -39,7 +27,7 @@ type Logger struct {
 	// While logging, the file and line number of the
 	// invoking (calling) line can be printed out.
 	// This defines an offset that is applied to the call stack.
-	// If you you are using an own wrapper function, you
+	// If you are using an own wrapper function, you
 	// have to set this value to one
 	FuncCallIncrement int
 
@@ -101,27 +89,7 @@ func (l *Logger) log(level Level, message string, parameters ...any) {
 	}
 
 	// Get the name of the level to log
-	var levelName string
+	var levelName = fmt.Sprintf("%-5s", level)
-	switch level {
-	case LevelTrace:
-		levelName = "TRACE"
-	case LevelDebug:
-		levelName = "DEBUG"
-	case LevelInfo:
-		levelName = "INFO "
-	case LevelWarning:
-		levelName = "WARN "
-	case LevelError:
-		levelName = "ERROR"
-	case LevelFatal:
-		levelName = "FATAL"
-	}
-
-	if levelName == "" {
-		message = fmt.Sprintf("Invalid level value given: %d. Original message: ", level) + message
-		levelName = "WARN "
-		level = LevelWarning
-	}
 
 	printMessage := "[" + levelName + "] " + time.Now().Local().Format("2006-01-02 15:04:05") +
 		getSourceMessage(file, line, pc, *l) + " - " + fmt.Sprintf(message, parameters...)
@@ -266,29 +234,27 @@ func CloseFile() {
 	dLogger.CloseFile()
 }
 
-// GetLevelByName tries to convert the given level name to the represented level code.
+// GetLoggerFromEnv returns a logging instance configured
-// Allowed values are: 'trace', 'debug', 'info', 'warn', 'warning', 'error', 'panic' and 'fatal'
+// from the available environment variables.
-// If an incorrect level name was given an warning is logged and info will be returned
+//
-func GetLevelByName(levelName string) Level {
+// The environment variables have to be named like the struct
-	levelName = strings.ToLower(levelName)
+// fields in upper case with the prefix "LOGGER_".
-	switch levelName {
+// Sub structs are divided also by an underscore. Example:
-	case "trace":
+// "LOGGER_SUBCONFIG_DISABLED"
-		return LevelTrace
+//
-	case "debug":
+// If no env variable was found the default value of the given
-		return LevelDebug
+// logger struct will be used.
-	case "info":
+//
-		return LevelInfo
+// Note that only generic options can be set like:
-	case "warn", "warning":
+// - Print and Log Level
-		return LevelWarning
+// - Log path
-	case "error":
+// - ColoredOutput
-		return LevelError
+// - Tracing disabled
-	case "panic", "fatal":
+func GetLoggerFromEnv(defaultLogger *Logger) *Logger {
-		return LevelFatal
+	defaultLogger.ColoredOutput = getEnvBool("LOGGER_COLOREDOUTPUT", defaultLogger.ColoredOutput)
-
+	defaultLogger.PrintLevel = GetLevelByName(getEnvString("LOGGER_PRINTLEVEL", defaultLogger.PrintLevel.String()))
-	default:
+	defaultLogger.LogLevel = GetLevelByName(getEnvString("LOGGER_LOGLEVEL", defaultLogger.LogLevel.String()))
-		{
+	defaultLogger.LogFilePath = getEnvString("LOGGER_LOGFILEPATH", defaultLogger.LogFilePath)
-			Warning("Unable to parse the level name '%s'. Expected 'debug', 'info', 'warn', 'error' or 'fatal'", levelName)
+	defaultLogger.PrintSource = getEnvBool("LOGGER_PRINTSOURCE", defaultLogger.PrintSource)
-			return LevelInfo
+	return NewLogger(defaultLogger)
-		}
-	}
 }