Add Log4j 1 to Log4j 2 configuration file conversion #202

ppkarwasz · 2024-12-18T14:41:38Z

What's changed?

This PR uses the Log4j Configuration Converter API to add a Log4j1ConfigurationToLog4jCore2 rule, which converts log4j.properties and log4j.xml configuration files into the equivalent log4j2.xml configuration files.

It also refactors the Log4j1toLog4j2 recipe into three parts:

Log4j1toLog4jAPI performs the migration from the "Log4j 1 API" to Log4j API 2, as described in Log4j 1 API migration. This recipe performs almost exclusively Java code changes and is usually not required in applications that use JCL or SLF4J as logging interface.
Log4j1ConfigurationToLog4jCore2 migrates configuration files, as described in the Log4j 1 Configuration file migration section.
Log4j1ToLog4jCore2 migrates the runtime dependencies to use Log4j Core 2 instead of Log4j 1, as described in Log4j 1 Backend migration and also calls the previous recipe. This is probably the most useful recipe for users that no longer user Log4j 1 directly, but use it as logging implementation.

What's your motivation?

This PR includes the last missing ingredient for a complete Log4j 1 to Log4j API/Core 2 migration: the conversion of configuration files.

Anything in particular you'd like reviewers to focus on?

This PR is a draft, since the "Log4j Configuration Converter API" it uses hasn't been published yet. We will publish log4j-converter-config as soon as we are reasonably sure that it can be used in OpenRewrite without modifications.

The configuration converter recipe is special, since not only it rewrites the content of a file, but it also can change its type (e.g. from Properties.File to XML.Document). Currently the recipe:

parses the bytes returned by the "Log4j Configuration Converter API" as UTF-8,
it writes them as SourceFile of type PlainText regardless of the actual type of the converted file and encodes the file using UTF-8.

Is there a way to skip the decoding/encoding of the converted configuration file? I tried Binary, but in that case printAllAsBytes() fails.

Anyone you would like to review specifically?

@timtebeek

Checklist

I've added unit tests to cover both positive and negative cases
I've read and applied the recipe conventions and best practices
I've used the IntelliJ IDEA auto-formatter on affected files

This PR uses the [Log4j Configuration Converter API](https://logging.staged.apache.org/log4j/transform/log4j-converter-config.html) to add a `Log4j1ConfigurationToLog4jCore2` rule, which converts `log4j.properties` and `log4j.xml` configuration files into the equivalent `log4j2.xml` configuration files. It also refactors the `Log4j1toLog4j2` recipe into three parts: - `Log4j1toLog4jAPI` performs the migration from the "Log4j 1 API" to Log4j API 2, as described in [Log4j 1 API migration](https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html#api-migration). This recipe performs almost exclusively Java code changes and is usually not required in applications that use JCL or SLF4J as logging interface. - `Log4j1ConfigurationToLog4jCore2` migrates configuration files, as described in the [Log4j 1 Configuration file migration](https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html#configuration-file-migration) section. - `Log4j1ToLog4jCore2` migrates the runtime dependencies to use Log4j Core 2 instead of Log4j 1, as described in [Log4j 1 Backend migration](https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html#backend-migration) and also calls the previous recipe. This is probably the most useful recipe for users that no longer user Log4j 1 directly, but use it as logging implementation. Closes openrewrite#154. Related to apache/logging-log4j2#3220

src/main/java/org/openrewrite/java/logging/ConvertConfiguration.java

src/test/java/org/openrewrite/java/logging/ConvertConfigurationTest.java

src/main/java/org/openrewrite/java/logging/ConvertConfiguration.java

src/test/java/org/openrewrite/java/logging/ConvertConfigurationTest.java

timtebeek · 2024-12-18T16:09:58Z

Thanks @ppkarwasz ! The bot suggestions can be a little confusing at times; it wants you to place the static imports last if that was unclear before. I'll try to review in the coming days! Right now caught up midway through a release and some meetings.

src/main/java/org/openrewrite/java/logging/ConvertConfiguration.java

src/test/java/org/openrewrite/java/logging/ConvertConfigurationTest.java

src/main/java/org/openrewrite/java/logging/ConvertConfiguration.java

src/test/java/org/openrewrite/java/logging/ConvertConfigurationTest.java

ppkarwasz · 2024-12-19T14:10:09Z

@timtebeek,

The bot suggestions can be a little confusing at times; it wants you to place the static imports last if that was unclear before.

They are indeed confusing, thanks for the explanation.

I'll try to review in the coming days! Right now caught up midway through a release and some meetings.

I am also working on the 0.3.0 release of Log4j Transform. Unless there are radical changes we need to do in Log4j Transform, this PR can wait until 0.3.0 is released.

timtebeek

Had a closer look already and applied some polish & suggestions. Thanks for working on these recipes ahead of the release! Should help adoption I imagine. Do let us know if you'd like to coordinate a merge and patch release of rewrite-logging-frameworks at some point.

timtebeek · 2025-01-01T16:19:48Z

build.gradle.kts


    implementation("org.apache.logging.log4j:log4j-core:2.+")
    implementation("org.slf4j:slf4j-api:2.+")
+    implementation("org.apache.logging.log4j:log4j-converter-config:0.3.0-SNAPSHOT")


Indeed likely best to merge this once released; thanks for creating the recipe before then!

Suggested change

implementation("org.apache.logging.log4j:log4j-converter-config:0.3.0-SNAPSHOT")

implementation("org.apache.logging.log4j:log4j-converter-config:latest.release")

timtebeek · 2025-01-01T16:20:05Z

build.gradle.kts

+repositories {
+    mavenCentral()
+    mavenLocal()
+    // Temporarily add Apache Snapshot repository for Log4j artifacts
+    maven {
+        setUrl("https://repository.apache.org/snapshots")
+        mavenContent {
+            // Excessive 404 result codes in `repository.apache.org` will ban the worker IP
+            // https://infra.apache.org/infra-ban.html
+            snapshotsOnly()
+            excludeGroupAndSubgroups("org.openrewrite")
+        }
+    }
+}
+


Similarly best removed before a merge.

Suggested change

repositories {

mavenCentral()

mavenLocal()

// Temporarily add Apache Snapshot repository for Log4j artifacts

maven {

setUrl("https://repository.apache.org/snapshots")

mavenContent {

// Excessive 404 result codes in `repository.apache.org` will ban the worker IP

// https://infra.apache.org/infra-ban.html

snapshotsOnly()

excludeGroupAndSubgroups("org.openrewrite")

}

}

}

timtebeek · 2025-01-01T16:20:51Z

build.gradle.kts


    testImplementation("org.openrewrite:rewrite-kotlin:${rewriteVersion}")
-    testImplementation("org.openrewrite:rewrite-maven")
+    testImplementation("org.openrewrite:rewrite-properties:${rewriteVersion}")


This rewrite-bom manages the version here, so we can leave that out already.

Suggested change

testImplementation("org.openrewrite:rewrite-properties:${rewriteVersion}")

testImplementation("org.openrewrite:rewrite-properties")

timtebeek · 2025-01-01T16:21:53Z

src/main/java/org/openrewrite/java/logging/ConvertConfiguration.java

+                    converter.convert(inputStream, inputFormat, outputStream, outputFormat);
+                    String utf8 = new String(outputStream.toByteArray(), StandardCharsets.UTF_8);
+
+                    return PlainTextParser.convert(sourceFile)


It looks like the output files are actually XML; should we use the XML parser here to read the converted contents such that subsequent recipes can optionally target their contents as part of the same recipe run?

This is exactly the main question I had for you. The log4j-converter-config artifact can convert to multiple formats (right now log4j2.xml, log4j2.json, log4j2.yaml and log4j2.properties are supported).

In the "Log4j 1 to Log4j Core 2" recipe I only use the XML output, but the ConvertConfiguration recipe could be used by users for other conversions. Should I make a switch here on outputFormat and use PlainText only if the format is not one of the recognized ones?

github-actions · 2025-04-16T11:33:54Z

This PR is stale because it has been open for 90 days with no activity. Remove stale label or comment or this will be closed in 7 days.

ppkarwasz · 2025-04-16T20:33:12Z

I didn't have time to release Apache Log4j Transformer yet, but this PR is on my TODO list.

github-actions · 2025-07-21T05:03:08Z

This PR is stale because it has been open for 90 days with no activity. Remove stale label or comment or this will be closed in 7 days.

ppkarwasz · 2025-07-21T07:04:48Z

I still plan to deliver this, although the ETA is not certain.
It is now on the top of the TODO list, so by end of August/September I should be able to manage a log4j-transform release.

github-actions · 2025-10-20T04:46:23Z

This PR is stale because it has been open for 90 days with no activity. Remove stale label or comment or this will be closed in two weeks. PRs may be reopened when there is renewed interest.

ppkarwasz · 2025-10-20T04:59:16Z

I was still unable to make a log4j-transform release, but it is still on the TODO list.

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timtebeek assigned ppkarwasz Dec 18, 2024

timtebeek self-requested a review December 18, 2024 16:10

ppkarwasz added 2 commits December 19, 2024 14:15

Fix imports

0bd6cf9

Use repository.apache.org only for snapshots

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Limit requests to repository.apache.org

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ppkarwasz and others added 4 commits December 19, 2024 15:12

Reverts changes to Slf4jToLog4jTest

599234e

Merge branch 'main' into feature/log4j1-to-log4j-core

608f1c9

Run ./gradlew downloadRecipeDependencies to update jars

4d9a3bc

Light polish

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timtebeek reviewed Jan 1, 2025

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Update classes to expect a newer version of the log4j jars

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ppkarwasz mentioned this pull request Aug 28, 2025

Apply the MSAL license #199

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	implementation("org.apache.logging.log4j:log4j-converter-config:0.3.0-SNAPSHOT")
	implementation("org.apache.logging.log4j:log4j-converter-config:latest.release")

	testImplementation("org.openrewrite:rewrite-properties:${rewriteVersion}")
	testImplementation("org.openrewrite:rewrite-properties")

Add Log4j 1 to Log4j 2 configuration file conversion #202

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What's changed?

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Checklist

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ppkarwasz commented Dec 18, 2024 •

edited by timtebeek

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