How to disable Jetty logging inside Javalin?

Question

I'm working on a Minecraft plugin and want to use Javalin. I can easily disable the Javali-logging with JavalinLogger.enabled = false but I can't disable the jetty log.

I always get the following output when starting the Javalin server:

[22:24:32 INFO]: [org.eclipse.jetty.server.Server] jetty-11.0.12; built: 2022-09-14T02:38:00.723Z; git: d5b8c29485f5f56a14be5f20c2ccce81b93c5555; jvm 17+35-LTS-2724
[22:24:32 INFO]: [org.eclipse.jetty.server.session.DefaultSessionIdManager] Session workerName=node0
[22:24:32 INFO]: [org.eclipse.jetty.server.handler.ContextHandler] Started i.j.j.@3293e900{/,null,AVAILABLE}
[22:24:32 INFO]: [org.eclipse.jetty.server.AbstractConnector] Started ServerConnector@4c57aa18{HTTP/1.1, (http/1.1)}{0.0.0.0:80}
[22:24:32 INFO]: [org.eclipse.jetty.server.Server] Started Server@34f89e1c{STARTING}[11.0.12,sto=0] @4657581ms

These are my dependencies in my pom.xml:

<dependency>
    <groupId>org.spigotmc</groupId>
    <artifactId>spigot-api</artifactId>
    <version>1.19.2-R0.1-SNAPSHOT</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>io.javalin</groupId>
    <artifactId>javalin</artifactId>
    <version>5.1.2</version>
</dependency>

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>2.0.3</version>
</dependency>

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.13.4.2</version>
</dependency>

I already tried the following:

• Setting different system properties e.g. org.eclipse.jetty.LEVEL
• Adding slf4j-simple and an simplelogger.properties
  • Tried the same thing with log4j
  • And with logback

Edit 1: After just implementing the source of slf4j-simple I realized that jetty is not using that at all. No Instance of SimpleLogger gets created. But if I just remove the slf4j provider entirely jetty doesn't log anymore but Javalin is throwing a huge warning that no providers were found

Edit 2: Steps to recreate the problem

1. Create a new Project inside IntelliJ with the "Minecraft" plugin
2. Choose Spigot and Version 1.19.2
3. I edited two Files:

pom.xml, Added following dependencies:

<dependency>
    <groupId>io.javalin</groupId>
    <artifactId>javalin</artifactId>
    <version>5.1.2</version>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>2.0.3</version>
</dependency>

The "main" java file that has the onEnable() method

@Override
public void onEnable() {
    // Plugin startup logic
    System.setProperty(org.slf4j.simple.SimpleLogger.DEFAULT_LOG_LEVEL_KEY, "OFF");

    JavalinLogger.enabled = false;

    ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    Thread.currentThread().setContextClassLoader(this.getClassLoader());
    Javalin app = Javalin.create();
    Thread.currentThread().setContextClassLoader(classLoader);
    app.get("/", ctx -> ctx.result("Hello World!"));
    app.start();
}

This creates the following output (on Paper 1.19.2):

[02:39:47 INFO]: [Javalintest] Enabling Javalintest v1.0-SNAPSHOT
[02:39:48 INFO]: [org.eclipse.jetty.server.Server] jetty-11.0.12; built: 2022-09-14T02:38:00.723Z; git: d5b8c29485f5f56a14be5f20c2ccce81b93c5555; jvm 17+35-LTS-2724
[02:39:48 INFO]: [org.eclipse.jetty.server.session.DefaultSessionIdManager] Session workerName=node0
[02:39:48 INFO]: [org.eclipse.jetty.server.handler.ContextHandler] Started i.j.j.@2f6e3e6c{/,null,AVAILABLE}
[02:39:48 INFO]: [org.eclipse.jetty.server.AbstractConnector] Started ServerConnector@17e2d1ec{HTTP/1.1, (http/1.1)}{0.0.0.0:8080}
[02:39:48 INFO]: [org.eclipse.jetty.server.Server] Started Server@5f91e5cc{STARTING}[11.0.12,sto=0] @14943ms
[02:39:48 INFO]: Running delayed init tasks
[02:39:48 INFO]: Done (4.288s)! For help, type "help"
[02:39:48 INFO]: Timings Reset

Answer 1

Spigot / Bukkit uses java.util.logging for it's environment (which can easily be different than what your standalone environment is using).

The typical way to access THE logger in Spigot / Bukkit is via ..

Logger logger = Bukkit.getLogger();
logger.info("This is my log message");

There is only 1 Logger when you are running in Spigot / Bukkit.

This logger is a java.util.logging.Logger instance.

See: https://hub.spigotmc.org/stash/projects/SPIGOT/repos/bukkit/browse/src/main/java/org/bukkit/Bukkit.java#819

That means you have to have a valid environment for logging for slf4j and in turn Jetty.

To do that, ensure that your Spigot / Bukkit environment has the slf4j-jdk14 dependency present, along with the slf4j-api dependency. Be careful these might be present courtesy of a different pluging running in your Spigot / Bukkit environment, don't stomp on them.

• https://search.maven.org/artifact/org.slf4j/slf4j-jdk14
• https://search.maven.org/artifact/org.slf4j/slf4j-api

Now, once you have a valid setup for the dependencies, you'll need to configure what that logging is doing.

The simplest solution is to just set the org.eclipse.jetty tree to a more restricted level.

// using java.util.logging
Logger logger = Logger.getLogger("org.eclipse.jetty");
logger.setLevel(Level.WARN); // good idea to see bad issues.

Keep in mind that you are operating with many other plugins in your Spigot / Bukkit environment, another plugin could have initialized javalin before you, rendering the above line of code useless (as it happens far too late).