feat: Support configuring rule.Reason as a Sprintf format string

So we can define one templated Reason to generate many Reasons, e.g.
generating Reasons for Nvidia GPU Xid errors in dmesg log.

Author: jessehu

pkg/systemlogmonitor/log_monitor.go

@@ -20,6 +20,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"regexp"
+	"strings"
 	"time"
 
 	"k8s.io/klog/v2"
@@ -157,6 +159,9 @@ func (l *logMonitor) parseLog(log *systemlogtypes.Log) {
 			continue
 		}
 		status := l.generateStatus(matched, rule)
+		if status == nil {
+			continue
+		}
 		klog.Infof("New status generated: %+v", status)
 		l.output <- status
 	}
@@ -169,12 +174,31 @@ func (l *logMonitor) generateStatus(logs []*systemlogtypes.Log, rule systemlogty
 	message := generateMessage(logs, rule.PatternGeneratedMessageSuffix)
 	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)
+		}
+	}
+	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 {
 		// For temporary error only generate event
 		events = append(events, types.Event{
 			Severity:  types.Warn,
 			Timestamp: timestamp,
-			Reason:    rule.Reason,
+			Reason:    reason,
 			Message:   message,
 		})
 	} else {
@@ -185,19 +209,19 @@ func (l *logMonitor) generateStatus(logs []*systemlogtypes.Log, rule systemlogty
 				// Update transition timestamp and message when the condition
 				// changes. Condition is considered to be changed only when
 				// status or reason changes.
-				if condition.Status == types.False || condition.Reason != rule.Reason {
+				if condition.Status == types.False || condition.Reason != reason {
 					condition.Transition = timestamp
 					condition.Message = message
 					events = append(events, util.GenerateConditionChangeEvent(
 						condition.Type,
 						types.True,
-						rule.Reason,
+						reason,
 						message,
 						timestamp,
 					))
 				}
 				condition.Status = types.True
-				condition.Reason = rule.Reason
+				condition.Reason = reason
 				changedConditions = append(changedConditions, condition)
 				break
 			}

pkg/systemlogmonitor/log_monitor_test.go

@@ -408,6 +408,150 @@ func TestGenerateStatusForMetrics(t *testing.T) {
 	}
 }
 
+func TestGenerateStatusForEvents(t *testing.T) {
+	for c, test := range []struct {
+		name     string
+		rule     logtypes.Rule
+		expected *types.Status
+		logs     []*logtypes.Log
+	}{
+		{
+			name: "without matching group",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): \\d+,.*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: &types.Status{
+				Source: testSource,
+				Events: []types.Event{{
+					Severity:  types.Warn,
+					Timestamp: time.Unix(1000, 1000),
+					Reason:    "NvidiaGPUXid",
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				}},
+			},
+		},
+		{
+			name: "one matching group",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid%s",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): (\\d+),.*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: &types.Status{
+				Source: testSource,
+				Events: []types.Event{{
+					Severity:  types.Warn,
+					Timestamp: time.Unix(1000, 1000),
+					Reason:    "NvidiaGPUXid45",
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				}},
+			},
+		},
+		{
+			name: "two matching groups",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid%s, Ch%s",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): (\\d+), Ch (\\d+).*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: &types.Status{
+				Source: testSource,
+				Events: []types.Event{{
+					Severity:  types.Warn,
+					Timestamp: time.Unix(1000, 1000),
+					Reason:    "NvidiaGPUXid45, Ch00000010",
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				}},
+			},
+		},
+		{
+			name: "not enough matching groups 1",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid%s, Ch%s",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): (\\d+),.*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: nil,
+		},
+		{
+			name: "not enough matching groups 2",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid%s",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): \\d+,.*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: nil,
+		},
+		{
+			name: "indexed matching groups",
+			rule: logtypes.Rule{
+				Type:    types.Temp,
+				Reason:  "NvidiaGPUXid%[1]s, Ch%[2]s",
+				Pattern: "NVRM: Xid \\(PCI:[^)]+\\): (\\d+), Ch (\\d+).*",
+			},
+			logs: []*logtypes.Log{
+				{
+					Timestamp: time.Unix(1000, 1000),
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				},
+			},
+			expected: &types.Status{
+				Source: testSource,
+				Events: []types.Event{{
+					Severity:  types.Warn,
+					Timestamp: time.Unix(1000, 1000),
+					Reason:    "NvidiaGPUXid45, Ch00000010",
+					Message:   "[...] NVRM: Xid (PCI:0000:00:00.0): 45, Ch 00000010",
+				}},
+			},
+		},
+	} {
+		l := &logMonitor{
+			config: MonitorConfig{
+				Source: testSource,
+			},
+		}
+		(&l.config).ApplyDefaultConfiguration()
+		got := l.generateStatus(test.logs, test.rule)
+
+		if !reflect.DeepEqual(test.expected, got) {
+			t.Errorf("case %d %s: expected status %+v, got %+v", c+1, test.name, test.expected, got)
+		}
+	}
+}
+
 func TestInitializeProblemMetricsOrDie(t *testing.T) {
 	testCases := []struct {
 		name            string