Apache Maven vs Bazel vs Gradle: What are the differences?

Introduction

Apache Maven, Bazel, and Gradle are popular build automation tools used in the software development process. While all three tools serve the purpose of building, testing, and packaging software, they have distinct differences that make them stand out from one another.

1. Build Language:

   Apache Maven uses XML as its build language, which provides declarative configuration. It follows a convention-over-configuration approach, where developers need to adhere to the predefined project structure and naming conventions. On the other hand, Bazel and Gradle use a more flexible and expressive build language. Bazel uses a domain-specific language called Starlark, while Gradle uses Groovy or Kotlin scripts for build configuration. This allows developers to have more control and expressiveness in defining the build process.

2. Build Performance:

   Bazel and Gradle offer improved build performance compared to Apache Maven. Bazel uses a fine-grained and incremental build system, which allows it to cache build artifacts and only build the necessary parts of the codebase, resulting in faster build times. Gradle also provides an incremental build feature, which intelligently analyzes the changes in the codebase and only rebuilds the affected parts. However, Apache Maven lacks such build optimizations and tends to have slower build times, especially for larger projects.

3. Build Scalability:

   Bazel excels in build scalability, particularly for large-scale projects or monorepos. It is designed to handle massive codebases by utilizing a distributed build system, where multiple machines can contribute resources for the build process. This enables Bazel to efficiently parallelize the build across multiple machines and reduce the overall build time. While Gradle also provides some level of build parallelization, it might not be as efficient as Bazel for extremely large projects. Apache Maven, on the other hand, doesn't offer built-in support for distributed builds or scalability.

4. Ecosystem and Plugin Support:

   Apache Maven has a mature and extensive ecosystem of plugins, making it easy to integrate with various tools, frameworks, and libraries. It has a wide range of plugins for common tasks like code quality, code coverage, deployment, and more. Bazel has a growing ecosystem of plugins and rules, but it might not be as comprehensive as Maven's ecosystem. Gradle also has a rich ecosystem of plugins, which is continuously expanding due to its increasing adoption. It offers a plugin system that allows developers to easily extend Gradle's functionality as per their requirements.

5. Compatibility and Portability:

   Apache Maven projects are generally highly portable and can be easily shared across different environments. It relies on standard directory structures and conventions, making it compatible with various IDEs and CI/CD tools out of the box. Bazel, on the other hand, requires a specific configuration and setup, which might not be as readily portable. Gradle provides a balance between the two, offering portability while also providing more flexibility in customizing the build process.

6. Intended Use Case:

   Apache Maven has been widely adopted in the Java ecosystem and is commonly used for traditional Java projects and frameworks. It provides a standardized way of building, testing, and packaging Java applications. Bazel, originally developed by Google, is geared towards large-scale software development and is commonly used for monorepos or projects with high reliance on dependency management and build scalability. Gradle, while also widely used in the Java ecosystem, aims to be a general-purpose build automation tool and supports multiple programming languages and platforms. It offers a flexible and extensible build system suitable for a variety of project types.

In Summary, Apache Maven relies on XML for configuration and follows a convention-over-configuration approach; Bazel and Gradle use more expressive build languages, offer better build performance and scalability, have different levels of ecosystem and plugin support, vary in compatibility and portability, and target different use cases.