A Telegram Appender for Logback

Introduction

Instead of applying complicated monitoring system to your appserver log file or using SMTPAppender relying on if and when you will read your email, you can get immediate alerts on a Telegram chat (with your bot) for critical errors by using a Telegram Appender.

Logback configuration

A sample configuration logback.xml is shown below

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
	<appender name="TELEGRAM"
		class="com.github.paolodenti.telegram.logback.TelegramAppender">
		<botToken>123456789123456789123456789123456789123456789</botToken>
		<chatId>123456789</chatId>
		<Layout class="ch.qos.logback.classic.PatternLayout">
			<Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</Pattern>
		</Layout>
	</appender>

	<root level="error">
		<appender-ref ref="TELEGRAM" />
	</root>
</configuration>

The botToken and chatId must be replaced with real values, do not use the above values.

The appender is intended to be used sparingly, just for critical errors because of the inherently low speed of http connection needed to send telegrams.

The following are optional properties:

• minInterval: threshold in milliseconds for message sending. If minInterval msecs are not passed from the last sent telegram, the new telegram is just discarded. Default value is 5000.
• connectTimeout: connection timeout to Telegram servers, in seconds. Default value is 5.
• connectionRequestTimeout: connection request timeout to Telegram servers, in seconds. Default value is 5.
• socketTimeout: socketTimeout to Telegram servers, in seconds. Default value is 5.
• messageParseMode: use styled messages. You can use html value to style the text with HTML tags or markdown value to use Markdown. Disabled by default.
• maxMessageSize: message is split in telegrams of maxMessageSize size. If the message is too big, Telegram does not send it. Current max accepted size by Telegram is 4096 but it could change in the future. Default is 1024.
• splitMessage: If true, all chunks of size maxMessageSize are sent. If false, only first chunk is sent. Default is true.
• nonBlocking: If true, each telegram is sent in a separate thread. Otherwise the send operation is blocking. Default is true.
• proxyHost: proxy server address
• proxyPort: proxy server port

A real usage scenario

Telegram appender should not be your only appender; telegram is to be used for critical errors. This is an example of logback configuration with multiple appenders, using telegram appender only on error level.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
	<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
		<encoder>
			<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
		</encoder>
	</appender>

	<appender name="TELEGRAM"
		class="com.github.paolodenti.telegram.logback.TelegramAppender">
		<botToken>123456789123456789123456789123456789123456789</botToken>
		<chatId>123456789</chatId>
		<Layout class="ch.qos.logback.classic.PatternLayout">
			<Pattern>%d{HH:mm:ss.SSS} %-5level %logger{36} - %msg%n</Pattern>
		</Layout>
		<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
		    <level>ERROR</level>
		</filter>
	</appender>

	<logger name="com.github.paolodenti.telegram.logback" level="DEBUG" />

	<root level="info">
		<appender-ref ref="STDOUT" />
		<appender-ref ref="TELEGRAM" />
	</root>
</configuration>

Example usage

telegram-logback is available on maven public repository. You just need to add the maven dependency

pom.xml

...
	<dependencies>
		<dependency>
			<groupId>com.github.paolodenti</groupId>
			<artifactId>telegram-logback</artifactId>
			<version>1.3.0</version>
		</dependency>

		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>1.7.25</version>
		</dependency>
	</dependencies>
...

App.java

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class App {
	private static Logger logger = LoggerFactory.getLogger("App");

	public static void main(String[] args) {
		logger.error("Telegram rulez!");
	}
}

Changelog

v. 1.2: Added http proxy server support

v. 1.3: Added formatting (by RodionKorneev)

How get botToken and chatId

In case you do not know how to get your botToken and chatId, these are simple instruction to follow in order to get the necessary configuration information.

As described in the Telegram Bot API, this is the manual procedure needed in order to get the necessary information.

1. Create the Bot and get the token
   • On a Telegram client open a chat with BotFather.
   • write /newbot to BotFather, fill all the needed information, write down the token. This is the botToken needed.
2. Create the destination chat and get the chatId
   • Open a new chat with your new Bot and post a message on the chat
   • Open a browser and invoke https://api.telegram.org/bot<botToken>/getUpdates (where <botToken> is the botToken previously obtained)
   • Look at the JSON result and write down the value of result[0].message.chat.id. That is the chatId. Note that if the chat is a group, the chat id is negative. If it is a single person, then positive.