Add support of user mentions for telegram alerting (#52)

- Also truncate the alert message and add three tail dots if too long.

README.md

@@ -142,7 +142,7 @@ Generally, system shall not report failure if auto resolved in a short time. How
 Provides utilities to hook middlewares to HTTP handler, e.g. remote address, API key and rate limit.
 
 ## Log
-We recommend initializing the log module from a configuration file or environment variables. Additionally, you can configure the alert hook to set up default notification channels for sending alert messages when `warning` or `error` logs occur.
+We recommend initializing the log module from a configuration file or environment variables.
 
 ```go
 // Initialize logging by specifying configurations
@@ -151,6 +151,13 @@ log.MustInit(conf)
 log.MustInitFromViper()
 ```
 
+Additionally, you can configure the alert hook to set up default notification channels for sending alert messages when `warning` or `error` logs occur. You can also customize notifications by specifying the target channel(s) through the `@channel` field in a Logrus entry.
+
+```go
+// Send alert to the 'tgrobot' channel instead.
+logrus.WithField("@channel": "tgrobot").Warn("Some warning occurred")
+```
+
 ### ErrorTolerantLogger
 `ErrorTolerantLogger` is a thread-safe logger that incorporates error tolerance behavior based on the continuous error count.
 

alert/formatter.go

@@ -14,6 +14,10 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+const (
+	maxAlertMsgLength = 1024 // max length for the alert message
+)
+
 // Formatter defines how messages are formatted.
 type Formatter interface {
 	Format(note *Notification) (string, error)
@@ -183,10 +187,12 @@ type TelegramMarkdownFormatter struct {
 	*markdownFormatter
 }
 
-func NewTelegramMarkdownFormatter(tags []string) (f *TelegramMarkdownFormatter, err error) {
+func NewTelegramMarkdownFormatter(tags, atUsers []string) (f *TelegramMarkdownFormatter, err error) {
 	funcMap := template.FuncMap{
-		"escapeMarkdown": escapeMarkdown,
-		"formatRFC3339":  formatRFC3339,
+		"escapeMarkdown":         escapeMarkdown,
+		"formatRFC3339":          formatRFC3339,
+		"truncateStringWithTail": truncateStringWithTail,
+		"mentions":               func() []string { return atUsers },
 	}
 	mf, err := newMarkdownFormatter(
 		tags, funcMap, telegramMarkdownTemplates[0], telegramMarkdownTemplates[1],
@@ -202,6 +208,17 @@ func escapeMarkdown(v interface{}) string {
 	return bot.EscapeMarkdown(fmt.Sprintf("%v", v))
 }
 
+// truncateStringWithTail is used to immediately truncate the input string to the max length limit.
+// A tail "..." is then added to the end of the string, if the string was longer than max length.
+func truncateStringWithTail(s string) string {
+	if len(s) > maxAlertMsgLength {
+		// Ttrim the string and add "..."
+		return s[:maxAlertMsgLength] + "..."
+	}
+
+	return s
+}
+
 type htmlFormatter struct {
 	*tplFormatter
 }

alert/telegram.go

@@ -13,8 +13,9 @@ var (
 )
 
 type TelegramConfig struct {
-	ApiToken string // Api token
-	ChatId   string // Chat ID
+	ApiToken string   // Api token
+	ChatId   string   // Chat ID
+	AtUsers  []string // Mention users
 }
 
 // TelegramChannel Telegram notification channel
@@ -26,7 +27,7 @@ type TelegramChannel struct {
 }
 
 func NewTelegramChannel(chID string, fmt Formatter, conf TelegramConfig) (*TelegramChannel, error) {
-	bot, err := bot.New(conf.ApiToken)
+	bot, err := bot.New(conf.ApiToken, bot.WithSkipGetMe())
 	if err != nil {
 		return nil, err
 	}

alert/templates.go

@@ -74,21 +74,23 @@ Reason
 *Tags*: {{.Tags | escapeMarkdown}}
 *Severity*: {{.Severity | escapeMarkdown}}
 *Time*: {{.Time | formatRFC3339 | escapeMarkdown}}
-*{{.Content | escapeMarkdown}}*
+*{{.Content | truncateStringWithTail ｜ escapeMarkdown}}*
+{{ range mentions }}@{{ . }} {{ end }}
 `,
 		`{{- /* logrus entry markdown template */ -}}
 *{{.Level | escapeMarkdown}}*
 *Tags*: {{.Tags | escapeMarkdown}}
 *Time*: {{.Time | formatRFC3339 | escapeMarkdown}}
 
 *Message*
-{{.Msg | escapeMarkdown}}
+{{.Msg | truncateStringWithTail | escapeMarkdown}}
 
 {{with .Error}}*Reason*
 {{.Error | escapeMarkdown}}
 
 {{else}}{{ end }}{{ if .CtxFields }}*Context Fields*:{{ range $Key, $Val := .CtxFields }}
-    *{{$Key | escapeMarkdown}}*: {{$Val | escapeMarkdown}}{{ end }}{{ end }}
+    *{{$Key | escapeMarkdown}}*: {{$Val | truncateStringWithTail | escapeMarkdown}}{{ end }}{{ end }}
+{{ range mentions }}@{{ . }} {{ end }}
 `,
 	}
 

alert/util.go

@@ -40,12 +40,17 @@ func parseAlertChannel(chID string, chmap map[string]interface{}, tags []string)
 
 		return NewDingTalkChannel(chID, fmt, dtconf), nil
 	case ChannelTypeTelegram:
+		if toStr, ok := chmap["atusers"].(string); ok {
+			mentions := strings.Split(toStr, ",")
+			chmap["atusers"] = mentions
+		}
+
 		var tgconf TelegramConfig
 		if err := decodeChannelConfig(chmap, &tgconf); err != nil {
 			return nil, err
 		}
 
-		fmt, err := NewTelegramMarkdownFormatter(tags)
+		fmt, err := NewTelegramMarkdownFormatter(tags, tgconf.AtUsers)
 		if err != nil {
 			return nil, err
 		}

config/config.yaml

@@ -54,6 +54,8 @@
 #       apiToken: ${your_api_token}
 #       # The chat ID for the Telegram chat where the alerts are sent.
 #       chatId: ${your_chat_id}
+#       # List of public usernames in the chat to be mentioned.
+#       atUsers: []
 
 #     # Example configuration for the SMTP (TLS/SSL only) email channel
 #     smtpbot: