Gradle Good Practices

2023 12 01 head

Gradle Build Tool is a fast, dependable, and adaptable open-source build automation tool with an elegant and extensible declarative build language. Java is the primary supported programming language.

Gradle Build Tool is a popular build system for the JVM and is the default system for Android and Kotlin Multi-Platform projects.

It has a rich community plugin ecosystem. Groovy, Kotlin, C++, and Swift stacks are well-supported.

Gradle is fast, scalable, and can build projects of any size and complexity.

Long ago I migrated all my projects from Maven to Gradle Build Tool [1].

In the first years, I sometimes regretted this decision due to missing or faulty plugins.

The plugins have now reached a level of maturity that you can do everything with Gradle [2].

Pros and Cons

Advantages

Great Flexibility

You can do everything within the build script as you write them with the full-fledged programming language Groovy or Kotlin based DSL.
XML is a data modeling language and probably the worst programming language ever used. The Maven approach to declarative builds is a reasonable idea, but the XML syntax is a nightmare.

Great Performance

Gradle does an awesome job in speeding up your builds with features like incremental builds, daemons, and clustered builds.

Great IDE Support

Jetbrains IntelliJ IDE has extensive Gradle support.

Drawbacks

Steep learning curve

Moreover, the whole team has to learn Gradle or you will be depending on the single Gradle ninja in your team.

Groovy or Kotlin DSL

The dynamic Groovy DSL and the heterogeneous plugin APIs will make you google everything. Unexpected side effects, behavior, and interdependencies between plugins often feel like magic. As Groovy is dynamically typed, it is really hard for IDEs to provide good and fast tooling. Contrarily, parsing and interpreting Maven’s XML is dead simple.

Breaking Changes

New Gradle versions are often breaking existing plugins, and the poor maintainer of these one-man-open-source-projects cannot keep up with this speed.

Best practices how Gradle Build Tool scripts should be structured have quite changed over the years. The Gradle Build Tool team has learned a lot and has impressively improved the tooling.

As a drawback, I had to regularly refactor my scripts to keep them up to date with best practices.

Maintain Your Build

Build rot is the silent degradation of your build system’s effectiveness. It is a result of poor practices, neglect, or simply the passage of time. It is like rust corroding a piece of machinery.

In this case, it gradually eats into the heart of your build system, causing it to slow down, become unpredictable, or become more challenging to maintain. This phenomenon can manifest within any build tool, but for our exploration.

What are the most common sources of build rot?

Dependencies

Poorly managed dependencies are one characteristic of build rot common to Maven and Gradle. Both build systems offer powerful dependency management capabilities. But neglecting regular updates to these dependencies can add vulnerable libraries to your build, directly impact build speed, and introduce compatibility issues.

An overly complex Gradle build.gradle or maven pom.xml file, cluttered with unnecessary dependencies or outdated plugins, can significantly extend build times and become a maintenance nightmare.

Use the Versions Plugin to identify outdated dependencies and plugins.
Define all your dependencies in a central version catalog configuration file.

Check your dependencies once a week and systematically update them. Use the latest version and run your unit and integration tests. If everything is green, you are good to go.

Over-customization

Gradle’s flexibility is one of its strong suits and yet it can ironically invite build rot. Over-customization, while seemingly advantageous in the short run, can result in a convoluted build.gradle files. These scripts can become so complicated that they require more effort to first comprehend and then maintain.

Define standard build processes as plugins in your buildSrc.
Eliminate all imperative logic from regular build.gradle scripts. Better follow the conventions and processes of standard plugins instead of creating custom logic.

We use this approach in our projects and Open Source Components to ensure a consistent build process across all projects.

Redundant tasks and misconfigured scripts

Moreover, this complexity can have a significant impact on build speed. If scripts include redundant tasks, or simply take a long time to execute your Groovy or Kotlin configuration, the build speed can slow to a frustrating crawl. Misconfigured scripts can also lead to extended test times, further exacerbating the build rot.

Always prefer standard plugins to build artifacts.

Suboptimal parallelization

Another silent perpetrator of build rot is the under-utilization of parallel execution capabilities offered by both Maven and Gradle. Both support parallel builds. Not taking advantage of this feature can lead to unnecessarily long build times. Similarly, not properly organizing your project into modules can result in unnecessary rebuilds of unchanged code, further slowing down your build process.

Modern software engineering practices promote modularity and low coupling between components.

Deprecated features and APIs

Sticking with deprecated features or APIs in your build scripts can also contribute to build rot. These deprecated features might be less efficient than their newer counterparts and might be removed in future build tool versions. The time and effort needed to refactor your scripts, once these features are eventually removed, add to the maintenance burden and deepen the build rot.

Refactoring is a mandatory practice to integrate improvements of your build tool into your scripts.

Lessons Learnt

Developers must understand the intricacies of these tools to use build systems like Maven and Gradle Build Tool to the greatest effect. By promoting a learning culture, you equip your team with the knowledge they need to best leverage these tools. Regular training and knowledge-sharing sessions can help reduce build rot and enhance productivity.

Each team of developers should have one savvy build tool expert. Do not rely on external consultants or the build tool vendor to solve your problems.

Update regularly your tools, plugins, and dependencies ensures you are leveraging the most efficient, optimized versions of libraries. This practice mitigates potential security issues and prevents the accumulation of update debt.

I mean it. Update every week. Run your continuous delivery pipeline to validate your changes. You reduce the risk of breaking changes and can react immediately. The updates remove known bugs and security issues.

Observability is critical in managing build rot.

Track your build and test times, identify trends, and analyze the impact of changes.


1. Last millennium I had to migrate all my projects from Apache Ant to Maven.
2. I had to wait until {ref-vaadin} provided an official supported Gradle Build Tool plugin.