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Lightrun – Third Party Code
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Flakiness in REST requests is a common issue. A request can get a 200 OK in one scenario and a 409 next time. Sometimes a request can even succeed and fail intermittently on the same exact request. In short, working over HTTP can be a bit of a mess without solid tooling.

Also, while it’s easy enough to debug these issues locally when developing the application, we’re talking about production here - we can’t afford the downtime while you’re stepping in and out of code. Uptime is kind of the whole point.

With Lightrun, you can get the same level of access you get with a local debugger or profiler - no downtime required. You can add logs, metrics, and snapshots (think breakpoints, but without stopping the running service), in a safe and read-only manner - without redeploying, restarting, or even stopping the running service. Performance and security are maintained throughout the process.

Learn how to debug a live REST API (built with Spring, of course), using Lightrun, in this 5-minute tutorial:

>> Debugging REST Requests in Spring-Based applications using the Lightrun Platform

1. Overview

In our previous tutorials, Spring Profiles and Logging in Spring Boot, we showed how to activate different profiles and use Log4j2 in Spring.

In this short tutorial, we'll learn how to use different Log4j2 configurations per Spring profile.

2. Use Different Properties Files

For example, suppose we have two files, log4j2.xml and log4j2-dev.xml, one for the default profile and the other for the “dev” profile.

Let's create our application.properties file and tell it where to find the logging config file:


Next, let's create a new properties file for our “dev” profile named application-dev.properties and add a similar line:


If we have other profiles – for example, “prod” – we only need to create a similarly named properties file – application-prod.properties for our “prod” profile. Profile-specific properties always override the default ones.

3. Programmatic Configuration

We can programmatically choose which Log4j2 configuration file to use by changing our Spring Boot Application class:

public class Application implements CommandLineRunner {

    private Environment env;

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);

    public void run(String... param) {
        if (Arrays.asList(env.getActiveProfiles()).contains("dev")) {
            Configurator.initialize(null, "/path/to/log4j2-dev.xml");
        } else {
            Configurator.initialize(null, "/path/to/log4j2.xml");

Configurator is a class of the Log4j2 library. It provides several ways to construct a LoggerContext using the location of the configuration file and various optional parameters.

This solution has one drawback: The application boot process won't be logged using Log4j2.

4. Conclusion

In summary, we've seen two approaches to using different Log4j2 configurations per Spring profile. First, we saw that we could provide a different properties file for each profile. Then, we saw an approach for configuring Log4j2 programmatically at application startup based on the active profile.

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