Pin compilation to JDK8 via Maven Toolchains by darklight3it · Pull Request #617 · aws/aws-lambda-java-libs

darklight3it · 2026-05-23T07:21:28Z

Issue #, if available:

Description of changes:

Add maven-toolchains-plugin to all packages requiring JDK [1.8,9). Builds now fail fast if no matching JDK 8 toolchain is configured, preventing silent issues like missing annotation processor output when building with higher JDKs.

Target (OCI, Managed Runtime, both): both

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

codecov · 2026-05-23T08:07:03Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.38%. Comparing base (8adb3d7) to head (3bdc951).
⚠️ Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #617   +/-   ##
=========================================
  Coverage     65.38%   65.38%           
  Complexity      211      211           
=========================================
  Files            34       34           
  Lines           988      988           
  Branches        142      142           
=========================================
  Hits            646      646           
  Misses          290      290           
  Partials         52       52

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The maven-toolchains-plugin requires JDK 8 to be declared in ~/.m2/toolchains.xml. The smoke test Docker agent has Corretto 8 installed but was missing this file, causing the build to fail.

rudraroop · 2026-07-15T10:26:12Z

+
+# Declare JDK 8 in toolchains.xml so maven-toolchains-plugin can resolve it
+RUN mkdir -p /root/.m2 && \
+    printf '<?xml version="1.0" encoding="UTF-8"?>\n<toolchains>\n  <toolchain>\n    <type>jdk</type>\n    <provides>\n      <version>8</version>\n    </provides>\n    <configuration>\n      <jdkHome>/usr/lib/jvm/java-1.8.0-amazon-corretto</jdkHome>\n    </configuration>\n  </toolchain>\n</toolchains>\n' > /root/.m2/toolchains.xml


Two points:

Minor nit -> hardcoding the jdkHome path -> Unlikely, but possible that base image changes where it installs Corretto 8 (different version suffix or directory). Then this would break as the path won't resolve - is there a better way to ensure coupling?

Readability of the printf line -> You can use a heredoc (<<) instead of a one-line unformatted xml string. That way the xml would appear properly formatted

Functionally, everything looks okay though

rudraroop

Looks okay. Only one actionable feedback for readability

benrkia · 2026-07-15T10:27:07Z

+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-toolchains-plugin</artifactId>
+                <version>3.2.0</version>
+                <configuration>
+                    <toolchains>
+                        <jdk>
+                            <!-- Range matches both "8" (e.g. actions/setup-java)
+                                 and "1.8" (legacy / hand-written toolchains). -->
+                            <version>[1.8,9)</version>
+                        </jdk>
+                    </toolchains>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>toolchain</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+


Nit: i see this is repeated across all the pom files, is it worth considering having a shared parent pom and have all the common stuff in there?

we have considered this. it might make sense when we automate the deployment, but for now each module is independently versioned and released to Maven Central and the CI builds them in isolation. a parent POM introduces coupling (any parent change needs to be published to maven central before any child module can be released). for this PR it feels safer to keep the modules self contained

benrkia · 2026-07-15T10:29:08Z

+
+# Declare JDK 8 in toolchains.xml so maven-toolchains-plugin can resolve it
+RUN mkdir -p /root/.m2 && \
+    printf '<?xml version="1.0" encoding="UTF-8"?>\n<toolchains>\n  <toolchain>\n    <type>jdk</type>\n    <provides>\n      <version>8</version>\n    </provides>\n    <configuration>\n      <jdkHome>/usr/lib/jvm/java-1.8.0-amazon-corretto</jdkHome>\n    </configuration>\n  </toolchain>\n</toolchains>\n' > /root/.m2/toolchains.xml


I'd create a file and do a copy instead of print if, that is better for maintainability

Also let's add an example tollchains.xml (toolchains.xml.example) for contributors

@benrkia I suggested a heredoc for readability instead of having a separate file + copy as it's only 10 lines of xml. What do you think?

I'd create a file and do a copy instead of print if, that is better for maintainability

I believe that his Dockerfile is built via stdin (

.PHONY: setup-codebuild-agent setup-codebuild-agent: docker build -t codebuild-agent \ --build-arg ARCHITECTURE=$(ARCHITECTURE_ALIAS) \ - < test/integration/codebuild-local/Dockerfile.agent

in the Makefile), which means there is no build context to COPY for local files won't work. we would need to refactor the Makefile to use -f with a build context directory to enable that.

right now i have switched to a heredoc with ${JAVA_HOME}, but happy to do the Makefile refactor if you think it would be nicer

I'm fine with that but let's add an example file and mention that in contribution.md so that people don't get failure because toolchain definition is missing

rudraroop

LGTM

Combine the maven-release-plugin/SCM/autoPublish config (this branch) with the maven-toolchains-plugin added on main (PR #617) so every module carries both plugins in a single <build> section.

Add .github/workflows/release.yml, a workflow_dispatch pipeline that builds, tests, and publishes a single module to Maven Central in one pinned JDK 8 environment, replacing the manual mvn deploy from a developer workstation. The release step prepares locally, publishes, then pushes the commits and module-scoped tag atomically, so a failed publish never leaves an orphan tag on the remote; a failure path rolls back the runner state. Releases are serialized repo-wide via a shared concurrency group. Signing/publishing secrets are not wired yet, so only the dry-run path (skip_publish) works without credentials for now. Set all module versions to -SNAPSHOT as the release plugin's expected starting point, and merge a duplicate top-level <build> section in the events POM introduced when the toolchains change (PR #617) met the release-plugin config on this branch.

build: Pin compilation to JDK 8 via Maven Toolchains

1901fac

darklight3it mentioned this pull request Jun 29, 2026

Add end-to-end integration tests #619

Merged

fix: Add toolchains.xml to codebuild agent for JDK 8 resolution

4acf4aa

The maven-toolchains-plugin requires JDK 8 to be declared in ~/.m2/toolchains.xml. The smoke test Docker agent has Corretto 8 installed but was missing this file, causing the build to fail.

darklight3it assigned darklight3it and fabisev and unassigned darklight3it Jul 15, 2026

fabisev marked this pull request as ready for review July 15, 2026 10:05

rudraroop reviewed Jul 15, 2026

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benrkia reviewed Jul 15, 2026

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Fabiana Severin added 2 commits July 15, 2026 11:57

fix: Use heredoc and $JAVA_HOME for toolchains.xml

8a3267a

docs: Add toolchains.xml example and setup guide

3bdc951

rudraroop approved these changes Jul 15, 2026

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benrkia approved these changes Jul 15, 2026

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Merge branch 'main' into dmelfi/pinning-java-8-version-via-toolchain

d539586

fabisev merged commit 69b9b2b into main Jul 15, 2026
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Pin compilation to JDK8 via Maven Toolchains#617

Pin compilation to JDK8 via Maven Toolchains#617
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