Gradle and the Challenges of Modern Build Tools

by Cédric Champeau (@CedricChampeau)

Who am I

speaker {
    name 'Cédric Champeau'
    company 'Gradle Inc'
    oss 'Apache Groovy committer',
    successes (['Static type checker',
                    'Static compilation',
                    'Traits',
                    'Markup template engine',
                    'DSLs'])
        failures Stream.of(bugs),
        twitter '@CedricChampeau',
        github 'melix',
        extraDescription '''Groovy in Action 2 co-author
Misc OSS contribs (Gradle plugins, deck2pdf, jlangdetect, ...)'''
}

Groovy in Action 2

koenig2

https://www.manning.com/books/groovy-in-action-second-edition

What is a build tool?

Make
Ant
Maven
Sbt
Grunt
Gradle
…

Why a build tool?

Automation
Integration of heterogeneous tools
- compiler
- code quality
- IDE
- deployment
Continuous integration
Continuous deployment

Software has evolved

Software is eating the world

No longer the IT crowd
From support to business

Different architectures

PHP
Big monolitic apps
Mobile apps
Multiplatform
Micro-services
Cloud

Different scale

Enterprise repositories
- Ivy
- Maven
- Docker
Enterprise builds
- Custom conventions
- Corporate policies

New requirements

TDD / BDD
Integration tests
Functional tests
Build pipelines

In a word: automation

Why Gradle

Polyglot programming

Java / Groovy / Scala / Clojure / Kotlin / …
Javascript
Native (C/C++/…)
Swift
Python
Ruby

Multi-project builds

SVN vs Git

Multiple branches
DVCS
Commit hash as version

Mono-repo vs multi-repo

Usual tooling not adapted to multi-repo
Mono-repo cumbersome
Composite builds?

Dependency management

Dependency substitution
Variant-aware
API vs implementation
Compile avoidance

Dependency management

Dynamic versions caching / tuning
NPM anyone?
Build reproducibility

Deep modeling

Conventions are not rules

Models first
- I want to build a Java library
- I want to build an Android application
- I want to build a micro-service
- I want to build a Gradle plugin

Tools should not get in the way

Tools should model those
Conventions should be model aware

A Java library

model {
    components {
        main(JvmLibrarySpec) {
            targetPlatform 'java8'
            targetPlatform 'java9'
            api {
               exports 'com.acme.mylib'
            }
        }
    }
    testSuites {
        test(JUnitTestSuiteSpec) {
            jUnitVersion '4.12'
            testing $.components.main
        }
    }
}