plugin/kubernetes : make kubernetes client log in CoreDNS format (#5461)

Signed-off-by: Ondřej Benkovský <ondrej.benkovsky@jamf.com>

plugin/kubernetes/logger.go

@@ -0,0 +1,38 @@
+package kubernetes
+
+import (
+	clog "github.com/coredns/coredns/plugin/pkg/log"
+
+	"github.com/go-logr/logr"
+)
+
+// loggerAdapter is a simple wrapper around CoreDNS plugin logger made to implement logr.LogSink interface, which is used
+// as part of klog library for logging in Kubernetes client. By using this adapter CoreDNS is able to log messages/errors from
+// kubernetes client in a CoreDNS logging format
+type loggerAdapter struct {
+	clog.P
+}
+
+func (l *loggerAdapter) Init(_ logr.RuntimeInfo) {
+}
+
+func (l *loggerAdapter) Enabled(_ int) bool {
+	// verbosity is controlled inside klog library, we do not need to do anything here
+	return true
+}
+
+func (l *loggerAdapter) Info(_ int, msg string, _ ...interface{}) {
+	l.P.Info(msg)
+}
+
+func (l *loggerAdapter) Error(_ error, msg string, _ ...interface{}) {
+	l.P.Error(msg)
+}
+
+func (l *loggerAdapter) WithValues(_ ...interface{}) logr.LogSink {
+	return l
+}
+
+func (l *loggerAdapter) WithName(_ string) logr.LogSink {
+	return l
+}