fix: Allow capturing groups in rule.Pattern with non-templated rule.Reason

Author: jessehu

pkg/systemlogmonitor/log_monitor.go

@@ -176,22 +176,24 @@ func (l *logMonitor) generateStatus(logs []*systemlogtypes.Log, rule systemlogty
 	var events []types.Event
 	var changedConditions []*types.Condition
 
-	// Support configuring rule.Reason as a Sprintf format string and formatting it with the matched capturing groups in rule.Pattern.
-	re := regexp.MustCompile(rule.Pattern)
-	matches := re.FindStringSubmatch(message)
 	reason := rule.Reason
-	formatArgs := make([]interface{}, 0)
-	if len(matches) > 1 {
-		// Use the matched capturing groups as the arguments for Sprintf.
-		for _, value := range matches[1:] {
-			formatArgs = append(formatArgs, value)
+	// Support configuring rule.Reason as a Sprintf format string and formatting it with the matched capturing groups in rule.Pattern.
+	if strings.Contains(reason, "%") {
+		re := regexp.MustCompile(rule.Pattern)
+		matches := re.FindStringSubmatch(message)
+		formatArgs := make([]interface{}, 0)
+		if len(matches) > 1 {
+			// Use the matched capturing groups as the arguments for Sprintf.
+			for _, value := range matches[1:] {
+				formatArgs = append(formatArgs, value)
+			}
+		}
+		reason = fmt.Sprintf(rule.Reason, formatArgs...)
+		// If fmt.Sprintf fails, it will add "%!" for each failed template in the result string.
+		if strings.Contains(reason, "%!") {
+			klog.Errorf("Got wrong string %q for reason %q with pattern %q", reason, rule.Reason, rule.Pattern)
+			return nil
 		}
-	}
-	reason = fmt.Sprintf(rule.Reason, formatArgs...)
-	// If fmt.Sprintf fails, it will add "%!" for each failed template in the result string.
-	if strings.Contains(reason, "%!") {
-		klog.Errorf("Got wrong string %q for reason %q with pattern %q", reason, rule.Reason, rule.Pattern)
-		return nil
 	}
 
 	if rule.Type == types.Temp {

pkg/systemlogmonitor/log_monitor_test.go

@@ -537,6 +537,29 @@ func TestGenerateStatusForEvents(t *testing.T) {
 				}},
 			},
 		},
+		{
+			name: "using matching groups in Pattern but not in Reason",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "OOMKilling",
+				Pattern: "Killed process \\d+ (.+) total-vm:\\d+kB, anon-rss:\\d+kB, file-rss:\\d+kB.*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "kernel: Killed process 13357 (mysqld), UID 27, total-vm:4977676kB, anon-rss:3256736kB, file-rss:0kB, shmem-rss:0kB",
+				},
+			},
+			expected: &types.Status{
+				Source: testSource,
+				Events: []types.Event{{
+					Severity:  types.Warn,
+					Timestamp: time.Unix(1000, 1000),
+					Reason:    "OOMKilling",
+					Message:   "kernel: Killed process 13357 (mysqld), UID 27, total-vm:4977676kB, anon-rss:3256736kB, file-rss:0kB, shmem-rss:0kB",
+				}},
+			},
+		},
 	} {
 		l := &logMonitor{
 			config: MonitorConfig{