DPE University Training

Gradle Build Cache Deep Dive - Unstable Inputs Exercise

This is a hands-on exercise to go along with the Gradle Build Cache Deep Dive training module. In this exercise you will go over the following:

• Practice troubleshooting cache misses due to unstable inputs
• Get familiar with using input normalization

Prerequisites

• Finished going through the troubleshooting section in Gradle Build Cache Deep Dive

Develocity Authentication

If you haven't already done so, you can authenticate with the training Develocity service by running:

./gradlew provisionGradleEnterpriseAccessKey

The output of the task will indicate a browser window will come up from which you can complete the authentication:

Once the browser window comes up you can enter a title for the access key that will be created or go with the suggested title:

Once confirmed you will see the following message and you can close the browser window and return to the editor:

Steps

1. Open the Gradle project in this repository in an editor of your choice
2. Run ./gradlew :app:test twice. You will notice the task is not up-to-date

3. Create a couple of build scans to get insights: ./gradlew :app:test --scan
4. Perform a build scan comparison if more insights are needed

5. Notice the common-1.0.jar file input changed for the :app:test task. This is produced by the :common:jar task, whose MANIFEST.MF file input changed:

6. Inspect the file common/build/tmp/jar/MANIFEST.MF to figure out what is changing. Notice the timestamp variable:

7. Go to the common/build.gradle.kts and look at the jar task configuration:

8. Refer to the input normalization doc and add the appropriate configuration to app/build.gradle.kts

9. Run the :app:test task a couple of times to verify it's now UP-TO-DATE

Solution Reference

If you get stuck you can refer to the solution branch of this repository.