feat: add a EXCLUSION to the logger (#8212)

This feature is intended to help reduce noisy logs generated by routine Kubernetes probes and Prometheus scraping. While logs are essential, these specific requests (e.g., to /metrics and /api/healthz) generally don't provide useful information and tend to clutter the output.

The goal is to introduce functionality that effectively acts as the inverse of the existing EXPRESSION mode—allowing logging to be excluded based on a condition, rather than included.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8212
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: zokki <zokki.softwareschmiede@gmail.com>
Co-committed-by: zokki <zokki.softwareschmiede@gmail.com>

modules/log/event_writer_buffer_test.go

@@ -31,3 +31,49 @@ func TestBufferLogger(t *testing.T) {
 	logger.Close()
 	assert.Contains(t, bufferWriter.Buffer.String(), expected)
 }
+
+func TestBufferLoggerWithExclusion(t *testing.T) {
+	prefix := "ExclusionPrefix "
+	level := log.INFO
+	message := "something"
+
+	bufferWriter := log.NewEventWriterBuffer("test-buffer", log.WriterMode{
+		Level:     level,
+		Prefix:    prefix,
+		Exclusion: message,
+	})
+
+	logger := log.NewLoggerWithWriters(t.Context(), "test", bufferWriter)
+
+	logger.SendLogEvent(&log.Event{
+		Level:         log.INFO,
+		MsgSimpleText: message,
+	})
+	logger.Close()
+	assert.NotContains(t, bufferWriter.Buffer.String(), message)
+}
+
+func TestBufferLoggerWithExpressionAndExclusion(t *testing.T) {
+	prefix := "BothPrefix "
+	level := log.INFO
+	expression := ".*foo.*"
+	exclusion := ".*bar.*"
+
+	bufferWriter := log.NewEventWriterBuffer("test-buffer", log.WriterMode{
+		Level:      level,
+		Prefix:     prefix,
+		Expression: expression,
+		Exclusion:  exclusion,
+	})
+
+	logger := log.NewLoggerWithWriters(t.Context(), "test", bufferWriter)
+
+	logger.SendLogEvent(&log.Event{Level: log.INFO, MsgSimpleText: "foo expression"})
+	logger.SendLogEvent(&log.Event{Level: log.INFO, MsgSimpleText: "bar exclusion"})
+	logger.SendLogEvent(&log.Event{Level: log.INFO, MsgSimpleText: "foo bar both"})
+	logger.SendLogEvent(&log.Event{Level: log.INFO, MsgSimpleText: "none"})
+	logger.Close()
+
+	assert.Contains(t, bufferWriter.Buffer.String(), "foo expression")
+	assert.NotContains(t, bufferWriter.Buffer.String(), "bar")
+}