Netflix = freedom and responsibility

(The assignment operator is intentional)

What can Gradle Lint do?

4 Remove cruft

4 Bar practices that are universally bad

4 Sanitize dependencies

4 Keep Gradle version up-to-date

4 Auto-fix violations!

Gradle Lint in action

Apply it:allprojects { apply plugin: 'nebula.lint' gradleLint.rules = ['dependency-parentheses', 'dependency-tuple', ...]}

Run it:./gradlew lintGradle./gradlew build <-- also causes lintGradle to run

./gradlew fixGradleLint <-- fixes all problems for you

Unused dependencies4 Remove unused first-order dependencies

4 Add transitive dependencies with compile time references as first-order dependencies

4 Align fixed first-order dependency versions with transitives when conflict resolved

4 Shuffle first-order dependencies to the correct configurations (e.g. junit to testCompile)

Creating a simple lint rule

"All wars should be published to our binary repository"

1: Apply immediately after the war plugin

class AllWarsShouldBePublishedRule extends GradleLintRule {

@Override void visitApplyPlugin(MethodCallExpression call, String plugin) { if(plugin == 'war') { addLintViolation('WARs must be published') .insertAfter(call, "apply plugin: 'netflix.war-publish'") } }}

2: Apply only if it isn't already applied

class AllWarsShouldBePublishedRule extends GradleLintRule {

@Override void visitApplyPlugin(MethodCallExpression call, String plugin) { if(plugin == 'war') bookmark('applyWar', call) else if(plugin == 'netflix.war-publish') bookmark('applyWarPublish', call) }

@Override protected void visitClassComplete(ClassNode node) { if(bookmark('applyWar') && !bookmark('applyWarPublish')) { addLintViolation('WARs must be published') .insertAfter(bookmark('applyWar'), "apply plugin: 'netflix.war-publish'") }}

3: Replace the war plugin entirely

class AllWarsShouldBePublishedRule extends GradleLintRule {

@Override void visitApplyPlugin(MethodCallExpression call, String plugin) { if(plugin == 'war') bookmark('applyWar', call) else if(plugin == 'netflix.war-publish') bookmark('applyWarPublish', call) }

@Override protected void visitClassComplete(ClassNode node) { if(bookmark('applyWar') && !bookmark('applyWarPublish')) { addLintViolation('WARs must be published') .replaceWith(bookmark('applyWar'), "apply plugin: 'netflix.war-publish'") }}

4: Become Gradle model awareclass AllWarsShouldBePublishedRule extends GradleLintRule implements GradleModelAware {

@Override void visitApplyPlugin(MethodCallExpression call, String plugin) { bookmark('lastApplyPlugin', call) }

@Override protected void visitClassComplete(ClassNode node) { if(project.plugins.hasPlugin(WarPlugin) && !project.plugins.hasPlugin('netflix.war-publish')) { addLintViolation('WARs must be published') .insertAfter(bookmark('lastApplyPlugin'), "apply plugin: 'netflix.war-publish'") } }}

Resources

"How We Build Code at Netflix" -- Netflix techblog

github.com/nebula-plugins/gradle-lint-plugin