log4j 1.x

The sentry-log4j library provides Log4j 1.x support for Sentry via an Appender that sends logged exceptions to Sentry. Once this integration is configured you can also use Sentry’s static API, as shown on the usage page, in order to do things like record breadcrumbs, set the current user, or manually send events.

The source can be found on GitHub.


For other dependency managers see the central Maven repository.

The following examples configure a ConsoleAppender that logs to standard out at the INFO level and a SentryAppender that logs to the Sentry server at the WARN level. The ConsoleAppender is only provided as an example of a non-Sentry appender that is set to a different logging threshold, like one you may already have in your project.

Example configuration using the log4j.properties format:

# Enable the Console and Sentry appenders
log4j.rootLogger=INFO, Console, Sentry

# Configure the Console appender
log4j.appender.Console.layout.ConversionPattern=%d{HH:mm:ss.SSS} [%t] %-5p: %m%n

# Configure the Sentry appender, overriding the logging threshold to the WARN level

Alternatively, using the log4j.xml format:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

    <!-- Configure the Console appender -->
    <appender name="Console" class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
        value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"

    <!-- Configure the Sentry appender, overriding the logging threshold to the WARN level -->
    <appender name="Sentry" class="io.sentry.log4j.SentryAppender">
        <!-- Override the Sentry handler log level to WARN -->
        <filter class="org.apache.log4j.varia.LevelRangeFilter">
            <param name="levelMin" value="WARN" />

    <!-- Enable the Console and Sentry appenders, Console is provided as an example
 of a non-Sentry logger that is set to a different logging threshold -->
    <root level="INFO">
        <appender-ref ref="Console" />
        <appender-ref ref="Sentry" />

Next, you’ll need to configure your DSN (client key) and optionally other values such as environment and release. See the configuration page for ways you can do this.

It’s possible to add extra data to events thanks to the MDC and the NDC systems provided by Log4j 1.x.

By default all MDC parameters are stored under the “Additional Data” tab in Sentry. By specifying the mdctags option in your configuration you can choose which MDC keys to send as tags instead, which allows them to be used as filters within the Sentry UI.

void logWithExtras() {
  // MDC extras
  MDC.put("Environment", "Development");
  MDC.put("OS", "Linux");

  // This sends an event where the Environment and OS MDC values are set as additional data
  logger.error("This is a test");

import org.apache.log4j.Logger;
import org.apache.log4j.MDC;
import org.apache.log4j.NDC;

public class MyClass {
  private static final Logger logger = Logger.getLogger(MyClass.class);

  void logSimpleMessage() {
    // This sends a simple event to Sentry
    logger.error("This is a test");

  void logWithBreadcrumbs() {
    // Record a breadcrumb that will be sent with the next event(s),
    // by default the last 100 breadcrumbs are kept.
        new BreadcrumbBuilder().setMessage("User made an action").build()

    // This sends a simple event to Sentry
    logger.error("This is a test");

  void logWithExtras() {
    // MDC extras
    MDC.put("extra_key", "extra_value");
    // NDC extras are sent under 'log4J-NDC'
    // This sends an event with extra data to Sentry
    logger.error("This is a test");

  void logException() {
    try {
    } catch (Exception e) {
      // This sends an exception event to Sentry
      logger.error("Exception caught", e);

  void unsafeMethod() {
    throw new UnsupportedOperationException("You shouldn't call this!");

Sentry uses asynchronous communication by default, and so it is unnecessary to use an AsyncAppender.

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