Fold WarningLogger info Logger (#1205)

* Fold WarningLogger info Logger

* Update changelog

CHANGELOG.asciidoc

@@ -34,6 +34,7 @@ https://github.com/elastic/apm-agent-go/compare/v1.15.0...main[View commits]
 - Replace apm.DefaultTracer with an initialization function {pull}1189[#(1189)]
 - Remove transport.Default, construct a new Transport in each new tracer {pull}1195[#(1195)]
 - Add service name and version to User-Agent header {pull}1196[#(1196)]
+- Remove WarningLogger, add Warningf methe to Logger {pull}1205[#(1205)]
 - Replace Sampler with ExtendedSampler {pull}1206[#(1206)]
 
 [[release-notes-1.x]]

apmtest/testlogger.go

@@ -38,6 +38,11 @@ func (t TestLogger) Errorf(format string, args ...interface{}) {
 	t.l.Logf("[ERROR] "+format, args...)
 }
 
+// Warningf logs warning messages.
+func (t TestLogger) Warningf(format string, args ...interface{}) {
+	t.l.Logf("[WARNING] "+format, args...)
+}
+
 // LogfLogger is an interface with the a Logf method,
 // implemented by *testing.T and *testing.B.
 type LogfLogger interface {

config.go

@@ -387,7 +387,7 @@ func initialExitSpanMinDuration() (time.Duration, error) {
 // config for config attributes that have been removed (exist in old but not in attrs).
 //
 // On return from updateRemoteConfig, unapplied config will have been removed from attrs.
-func (t *Tracer) updateRemoteConfig(logger WarningLogger, old, attrs map[string]string) {
+func (t *Tracer) updateRemoteConfig(logger Logger, old, attrs map[string]string) {
 	warningf := func(string, ...interface{}) {}
 	debugf := func(string, ...interface{}) {}
 	errorf := func(string, ...interface{}) {}

logger.go

@@ -25,30 +25,7 @@ type Logger interface {
 
 	// Errorf logs a message at error level.
 	Errorf(format string, args ...interface{})
-}
-
-// WarningLogger extends Logger with a Warningf method.
-//
-// TODO(axw) this will be removed in v2.0.0, and the
-// Warningf method will be added directly to Logger.
-type WarningLogger interface {
-	Logger
 
 	// Warningf logs a message at warning level.
 	Warningf(format string, args ...interface{})
 }
-
-func makeWarningLogger(l Logger) WarningLogger {
-	if wl, ok := l.(WarningLogger); ok {
-		return wl
-	}
-	return debugWarningLogger{Logger: l}
-}
-
-type debugWarningLogger struct {
-	Logger
-}
-
-func (l debugWarningLogger) Warningf(format string, args ...interface{}) {
-	l.Debugf(format, args...)
-}

tracer.go

@@ -535,7 +535,7 @@ type tracerConfig struct {
 	requestSize         int
 	requestDuration     time.Duration
 	metricsInterval     time.Duration
-	logger              WarningLogger
+	logger              Logger
 	metricsGatherers    []MetricsGatherer
 	disabledMetrics     wildcard.Matchers
 	cpuProfileDuration  time.Duration
@@ -617,15 +617,12 @@ func (t *Tracer) SetMetricsInterval(d time.Duration) {
 // SetLogger sets the Logger to be used for logging the operation of
 // the tracer.
 //
-// If logger implements WarningLogger, its Warningf method will be used
-// for logging warnings. Otherwise, warnings will logged using Debugf.
-//
 // The tracer is initialized with a default logger configured with the
 // environment variables ELASTIC_APM_LOG_FILE and ELASTIC_APM_LOG_LEVEL.
 // Calling SetLogger will replace the default logger.
 func (t *Tracer) SetLogger(logger Logger) {
 	t.sendConfigCommand(func(cfg *tracerConfig) {
-		cfg.logger = makeWarningLogger(logger)
+		cfg.logger = logger
 	})
 }