opentelemetry-java-instrumentation/CONTRIBUTING.md

Contributing

Pull requests for bug fixes are welcome, but before submitting new features or changes to current functionality open an issue and discuss your ideas or propose the changes you wish to make. After a resolution is reached a PR can be submitted for review.

In order to fully build and test this whole repository you need the following:

• Installed both JDK 8 and 9.
• Java 8 should be set as default: java -version should give you version 8.
• Defined environment variables JAVA_8_HOME and JAVA_9_HOME which point to the corresponding java homes.

Testing

Java versions

Open Telemetry Auto Instrumentation's minimal supported version is java 7. All jar files that we produce, unless noted otherwise, have bytecode compatible with java 7 runtime. In addition to that we test our code with all later java versions as well: from 8 to 14.

Some libraries that we auto-instrument may have higher minimal requirements. In this case we compile and test corresponding auto-instrumentation with higher java version as required by library. The resulting classes will have higher bytecode level, but as it matches library's java version, no runtime problem arise.

Instrumentation tests

Executing ./gradlew instrumentation:test will run tests for all supported auto-instrumentations using that java version which runs the Gradle build itself. These tests usually use the minimal supported version of the instrumented library.

In addition to that each instrumentation has a separate test set called latestDepTest. It was created by Gradle test sets plugin. It uses the very same tests as before, but declares a dynamic dependency on the latest available version of this library. You can run them all by executing ./gradlew latestDepTest.

Executing tests with specific java version

In order to run tests on a specific java version, just execute ./gradlew testJava7 (or testJava11 or latestDepTestJava14 etc). Then Gradle task rule will kick in and do the following:

• check, if Gradle already runs on a java with required version
• if not, look for an environment variable named JAVA_N_HOME, where N is the requested java version
• if Gradle could not found requested java version, then build will fail
• Gradle will now find all corresponding test tasks and configure them to use java executable of the requested version.

This works both for tasks named test and latestDepTest. But currently does not work for other custom test tasks, such as those created by test sets plugin.

Style guideline

We follow the Google Java Style Guide. Our build will fail if source code is not formatted according to that style.

To verify code style manually run the following command, which uses google-java-format library:

./gradlew verifyGoogleJavaFormat

or on Windows

gradlew.bat verifyGoogleJavaFormat

Instead of fixing style inconsistencies by hand, you can run gradle task googleJavaFormat to automatically fix all found issues:

./gradlew googleJavaFormat

or on Windows

gradlew.bat googleJavaFormat

Pre-commit hook

To completely delegate code style formatting to the machine, you can add git pre-commit hook. We provide an example script in buildscripts/pre-commit file. Just copy or symlink it into .git/hooks folder.

Editorconfig

As additional convenience for IntelliJ Idea users, we provide .editorconfig file. Idea will automatically use it to adjust its code formatting settings. It does not support all required rules, so you still have to run googleJavaFormat from time to time.

Intellij IDEA

Required plugins:

• Lombok

Suggested plugins and settings:

• Editor > Code Style > Java/Groovy > Imports
  • Class count to use import with '*': 9999 (some number sufficiently large that is unlikely to matter)
  • Names count to use static import with '*': 9999
  • With java use the following import layout (groovy should still use the default) to ensure consistency with google-java-format:
• Google Java Format
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