Migrate Log4j to SLF4J

org.openrewrite.java.logging.slf4j.Log4jToSlf4j

Migrates usage of Apache Log4j to using SLF4J directly. Use of the traditional Log4j to SLF4J bridge can result in loss of performance, as the Log4j messages must be formatted before they can be passed to SLF4J. Note, this currently does not modify log4j.properties files.

Tags

• slf4j

• logging

• log4j

Recipe source

GitHub, Issue Tracker, Maven Central

• groupId: org.openrewrite.recipe

• artifactId: rewrite-logging-frameworks

• version: 2.5.0

This recipe is composed of more than one recipe. If you want to customize the set of recipes this is composed of, you can find and copy the GitHub source for the recipe from the link above.

Usage

This recipe has no required configuration options. It can be activated by adding a dependency on org.openrewrite.recipe:rewrite-logging-frameworks:2.5.0 in your build file or by running a shell command (in which case no build changes are needed):

Gradle

1. Add the following to your build.gradle file:

build.gradle

plugins {
    id("org.openrewrite.rewrite") version("6.11.2")
}

rewrite {
    activeRecipe("org.openrewrite.java.logging.slf4j.Log4jToSlf4j")
}

repositories {
    mavenCentral()
}

dependencies {
    rewrite("org.openrewrite.recipe:rewrite-logging-frameworks:2.5.0")
}

2. Run gradle rewriteRun to run the recipe.

Gradle init script

1. Create a file named init.gradle in the root of your project.

init.gradle

initscript {
    repositories {
        maven { url "https://plugins.gradle.org/m2" }
    }
    dependencies { classpath("org.openrewrite:plugin:6.11.2") }
}
rootProject {
    plugins.apply(org.openrewrite.gradle.RewritePlugin)
    dependencies {
        rewrite("org.openrewrite.recipe:rewrite-logging-frameworks:2.5.0")
    }
    rewrite {
        activeRecipe("org.openrewrite.java.logging.slf4j.Log4jToSlf4j")
    }
    afterEvaluate {
        if (repositories.isEmpty()) {
            repositories {
                mavenCentral()
            }
        }
    }
}

2. Run gradle --init-script init.gradle rewriteRun to run the recipe.

Maven POM

1. Add the following to your pom.xml file:

pom.xml

<project>
  <build>
    <plugins>
      <plugin>
        <groupId>org.openrewrite.maven</groupId>
        <artifactId>rewrite-maven-plugin</artifactId>
        <version>5.27.0</version>
        <configuration>
          <activeRecipes>
            <recipe>org.openrewrite.java.logging.slf4j.Log4jToSlf4j</recipe>
          </activeRecipes>
        </configuration>
        <dependencies>
          <dependency>
            <groupId>org.openrewrite.recipe</groupId>
            <artifactId>rewrite-logging-frameworks</artifactId>
            <version>2.5.0</version>
          </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>
</project>

2. Run mvn rewrite:run to run the recipe.

Maven Command Line

shell

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-logging-frameworks:RELEASE -Drewrite.activeRecipes=org.openrewrite.java.logging.slf4j.Log4jToSlf4j

Moderne CLI

You will need to have configured the Moderne CLI on your machine before you can run the following command.

shell

mod run . --recipe Log4jToSlf4j

Definition

Recipe List

• Migrate Log4j 1.x to SLF4J 1.x

• Loggers should be named for their enclosing classes

• Remove a Gradle or Maven dependency

  • groupId: org.apache.logging.log4j

  • artifactId: log4j-to-slf4j

• Upgrade Gradle or Maven dependency versions

  • groupId: org.apache.logging.log4j

  • artifactId: log4j-api

  • newVersion: latest.release

  • overrideManagedVersion: true

• Upgrade Gradle or Maven dependency versions

  • groupId: org.apache.logging.log4j

  • artifactId: log4j-core

  • newVersion: latest.release

  • overrideManagedVersion: true

• Add Gradle or Maven dependency

  • groupId: org.slf4j

  • artifactId: slf4j-api

  • version: latest.release

  • onlyIfUsing: org.apache.logging.log4j.*

• Add Gradle or Maven dependency

  • groupId: org.apache.logging.log4j

  • artifactId: log4j-slf4j2-impl

  • version: latest.release

  • onlyIfUsing: org.apache.logging.log4j.*

• Add Gradle or Maven dependency

  • groupId: org.slf4j

  • artifactId: slf4j-api

  • version: latest.release

  • onlyIfUsing: org.apache.log4j.*

• Add Gradle or Maven dependency

  • groupId: org.apache.logging.log4j

  • artifactId: log4j-slf4j2-impl

  • version: latest.release

  • onlyIfUsing: org.apache.log4j.*

• Change Gradle or Maven dependency

  • oldGroupId: org.apache.logging.log4j

  • oldArtifactId: log4j-slf4j-impl

  • newArtifactId: log4j-slf4j2-impl

  • newVersion: latest.release

Yaml Recipe List

---
type: specs.openrewrite.org/v1beta/recipe
name: org.openrewrite.java.logging.slf4j.Log4jToSlf4j
displayName: Migrate Log4j to SLF4J
description: Migrates usage of Apache Log4j to using SLF4J directly. Use of the traditional Log4j to SLF4J bridge can result in loss of performance, as the Log4j messages must be formatted before they can be passed to SLF4J. Note, this currently does not modify `log4j.properties` files.
tags:
  - slf4j
  - logging
  - log4j
recipeList:
  - org.openrewrite.java.logging.slf4j.Log4j1ToSlf4j1
  - org.openrewrite.java.logging.slf4j.LoggersNamedForEnclosingClass
  - org.openrewrite.java.dependencies.RemoveDependency:
      groupId: org.apache.logging.log4j
      artifactId: log4j-to-slf4j
  - org.openrewrite.java.dependencies.UpgradeDependencyVersion:
      groupId: org.apache.logging.log4j
      artifactId: log4j-api
      newVersion: latest.release
      overrideManagedVersion: true
  - org.openrewrite.java.dependencies.UpgradeDependencyVersion:
      groupId: org.apache.logging.log4j
      artifactId: log4j-core
      newVersion: latest.release
      overrideManagedVersion: true
  - org.openrewrite.java.dependencies.AddDependency:
      groupId: org.slf4j
      artifactId: slf4j-api
      version: latest.release
      onlyIfUsing: org.apache.logging.log4j.*
  - org.openrewrite.java.dependencies.AddDependency:
      groupId: org.apache.logging.log4j
      artifactId: log4j-slf4j2-impl
      version: latest.release
      onlyIfUsing: org.apache.logging.log4j.*
  - org.openrewrite.java.dependencies.AddDependency:
      groupId: org.slf4j
      artifactId: slf4j-api
      version: latest.release
      onlyIfUsing: org.apache.log4j.*
  - org.openrewrite.java.dependencies.AddDependency:
      groupId: org.apache.logging.log4j
      artifactId: log4j-slf4j2-impl
      version: latest.release
      onlyIfUsing: org.apache.log4j.*
  - org.openrewrite.java.dependencies.ChangeDependency:
      oldGroupId: org.apache.logging.log4j
      oldArtifactId: log4j-slf4j-impl
      newArtifactId: log4j-slf4j2-impl
      newVersion: latest.release

See how this recipe works across multiple open-source repositories

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Please contact Moderne for more information about safely running the recipes on your own codebase in a private SaaS.

Contributors

Aaron Gershman, Patrick, Sam Snyder, Knut Wannheden, Tim te Beek, Adriano Machado, Jonathan Schnéider, Tim te Beek, Kun Li, Peter Streef