Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

logger.go

@@ -0,0 +1,101 @@
+package telegraf
+
+// LogLevel denotes the level for logging
+type LogLevel int
+
+const (
+	// None means nothing is logged
+	None LogLevel = iota
+	// Error will log error messages
+	Error
+	// Warn will log error messages and warnings
+	Warn
+	// Info will log error messages, warnings and information messages
+	Info
+	// Debug will log all of the above and debugging messages issued by plugins
+	Debug
+	// Trace will log all of the above and trace messages issued by plugins
+	Trace
+)
+
+func LogLevelFromString(name string) LogLevel {
+	switch name {
+	case "ERROR", "error":
+		return Error
+	case "WARN", "warn":
+		return Warn
+	case "INFO", "info":
+		return Info
+	case "DEBUG", "debug":
+		return Debug
+	case "TRACE", "trace":
+		return Trace
+	}
+	return None
+}
+
+func (e LogLevel) String() string {
+	switch e {
+	case Error:
+		return "ERROR"
+	case Warn:
+		return "WARN"
+	case Info:
+		return "INFO"
+	case Debug:
+		return "DEBUG"
+	case Trace:
+		return "TRACE"
+	}
+	return "NONE"
+}
+
+func (e LogLevel) Indicator() string {
+	switch e {
+	case Error:
+		return "E!"
+	case Warn:
+		return "W!"
+	case Info:
+		return "I!"
+	case Debug:
+		return "D!"
+	case Trace:
+		return "T!"
+	}
+	return "U!"
+}
+
+func (e LogLevel) Includes(level LogLevel) bool {
+	return e >= level
+}
+
+// Logger defines an plugin-related interface for logging.
+type Logger interface { //nolint:interfacebloat // All functions are required
+	// Level returns the configured log-level of the logger
+	Level() LogLevel
+
+	// AddAttribute allows to add a key-value attribute to the logging output
+	AddAttribute(key string, value interface{})
+
+	// Errorf logs an error message, patterned after log.Printf.
+	Errorf(format string, args ...interface{})
+	// Error logs an error message, patterned after log.Print.
+	Error(args ...interface{})
+	// Warnf logs a warning message, patterned after log.Printf.
+	Warnf(format string, args ...interface{})
+	// Warn logs a warning message, patterned after log.Print.
+	Warn(args ...interface{})
+	// Infof logs an information message, patterned after log.Printf.
+	Infof(format string, args ...interface{})
+	// Info logs an information message, patterned after log.Print.
+	Info(args ...interface{})
+	// Debugf logs a debug message, patterned after log.Printf.
+	Debugf(format string, args ...interface{})
+	// Debug logs a debug message, patterned after log.Print.
+	Debug(args ...interface{})
+	// Tracef logs a trace message, patterned after log.Printf.
+	Tracef(format string, args ...interface{})
+	// Trace logs a trace message, patterned after log.Print.
+	Trace(args ...interface{})
+}