feature: add custom message for systemlogmonitor rule

pkg/systemlogmonitor/README.md

@@ -37,7 +37,8 @@ with new rule definition:
   "type": "temporary/permanent",
   "condition": "NodeConditionOfPermanentIssue",
   "reason": "CamelCaseShortReason",
-  "pattern": "regexp matching the issue in the log"
+  "pattern": "regexp matching the issue in the log",
+  "patternGeneratedMessageSuffix": "Please check the network connectivity and ensure that all required services are running. For more details, see our documentation at https://example.com/docs/troubleshooting."
 }
 ```
 

pkg/systemlogmonitor/config.go

@@ -46,7 +46,7 @@ type MonitorConfig struct {
 	EnableMetricsReporting *bool `json:"metricsReporting,omitempty"`
 }
 
-// ApplyConfiguration applies default configurations.
+// ApplyDefaultConfiguration applies default configurations.
 func (mc *MonitorConfig) ApplyDefaultConfiguration() {
 	if mc.BufferSize == 0 {
 		mc.BufferSize = defaultBufferSize

pkg/systemlogmonitor/log_monitor.go

@@ -18,6 +18,7 @@ package systemlogmonitor
 
 import (
 	"encoding/json"
+	"fmt"
 	"os"
 	"time"
 
@@ -165,7 +166,7 @@ func (l *logMonitor) parseLog(log *systemlogtypes.Log) {
 func (l *logMonitor) generateStatus(logs []*systemlogtypes.Log, rule systemlogtypes.Rule) *types.Status {
 	// We use the timestamp of the first log line as the timestamp of the status.
 	timestamp := logs[0].Timestamp
-	message := generateMessage(logs)
+	message := generateMessage(logs, rule.PatternGeneratedMessageSuffix)
 	var events []types.Event
 	var changedConditions []*types.Condition
 	if rule.Type == types.Temp {
@@ -250,10 +251,14 @@ func initialConditions(defaults []types.Condition) []types.Condition {
 	return conditions
 }
 
-func generateMessage(logs []*systemlogtypes.Log) string {
+func generateMessage(logs []*systemlogtypes.Log, patternGeneratedMessageSuffix string) string {
 	messages := []string{}
 	for _, log := range logs {
 		messages = append(messages, log.Message)
 	}
-	return concatLogs(messages)
+	logMessage := concatLogs(messages)
+	if patternGeneratedMessageSuffix != "" {
+		return fmt.Sprintf("%s; %s", logMessage, patternGeneratedMessageSuffix)
+	}
+	return logMessage
 }

pkg/systemlogmonitor/log_monitor_test.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/node-problem-detector/pkg/problemdaemon"
 	"k8s.io/node-problem-detector/pkg/problemmetrics"
 	logtypes "k8s.io/node-problem-detector/pkg/systemlogmonitor/types"
+	systemlogtypes "k8s.io/node-problem-detector/pkg/systemlogmonitor/types"
 	"k8s.io/node-problem-detector/pkg/types"
 	"k8s.io/node-problem-detector/pkg/util"
 	"k8s.io/node-problem-detector/pkg/util/metrics"
@@ -699,3 +700,40 @@ func TestInitializeProblemMetricsOrDie(t *testing.T) {
 		})
 	}
 }
+
+func TestGenerateMessage(t *testing.T) {
+	tests := []struct {
+		name                          string
+		logs                          []*systemlogtypes.Log
+		patternGeneratedMessageSuffix string
+		want                          string
+	}{
+		{
+			name: "No rule message",
+			logs: []*systemlogtypes.Log{
+				{Message: "First log message"},
+				{Message: "Second log message"},
+			},
+			patternGeneratedMessageSuffix: "",
+			want:                          "First log message\nSecond log message",
+		},
+		{
+			name: "With rule message",
+			logs: []*systemlogtypes.Log{
+				{Message: "First log message"},
+				{Message: "Second log message"},
+			},
+			patternGeneratedMessageSuffix: "refer www.foo.com/docs for playbook on how to fix the issue",
+			want:                          "First log message\nSecond log message; refer www.foo.com/docs for playbook on how to fix the issue",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := generateMessage(tt.logs, tt.patternGeneratedMessageSuffix)
+			if got != tt.want {
+				t.Errorf("generateMessage() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

pkg/systemlogmonitor/types/types.go

@@ -42,4 +42,9 @@ type Rule struct {
 	// Pattern is the regular expression to match the problem in log.
 	// Notice that the pattern must match to the end of the line.
 	Pattern string `json:"pattern"`
+	// PatternGeneratedMessageSuffix is an optional suffix appended to the matched pattern.
+	// This suffix provides additional context or instructions for resolving the issue.
+	// It can be used to include environment-specific details, links to documentation,
+	// or any other information that helps users understand and address the problem.
+	PatternGeneratedMessageSuffix string `json:"patternGeneratedMessageSuffix,omitempty"`
 }