This document discusses Netflix's use of Gradle Lint to enable distributed refactoring. Gradle Lint allows Netflix to define custom linting rules to validate and refactor Gradle builds across their monorepo. The document provides an example of a rule to enforce that all WAR projects are published to their binary repository. It demonstrates how the rule can be made more complex by applying the change immediately, only if needed, or replacing the WAR plugin entirely.

1. DISTRIBUTED
REFACTORING WITH
GRADLE LINT
Jon Schneider
Netflix Engineering Tools
@jon_k_schneider
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2. GITHUB.COM/NETFLIXGRADLESUMMIT/LINT

3. NETFLIX IS KNOWN FOR
RAPID INNOVATION.
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4. WE WANT TO MINIMIZE DRAG FROM LATE
ADOPTERS.
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5. NETFLIX CULTURE IS
FREEDOM AND RESPONSIBILITY
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6. GRADLE LINT
ALLOWS US TO
DISTRIBUTE
CHANGE.
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7. THE UNUSED
DEPENDENCIES
RULE HELPS
MAINTAIN GOOD
DEPENDENCY
HYGIENE.
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8. GRADLE LINT SUPPORTS
SHIPPING METRICS TO
nebula.metrics
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9. CREATING A MORE COMPLEX RULE
"All wars should be published to our
binary repository"
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10. 1: APPLY IMMEDIATELY AFTER THE WAR
PLUGIN
class AllWarsShouldBePublishedRule extends GradleLintRule {
@Override void visitApplyPlugin(MethodCallExpression call, String plugin) {
if(plugin == 'war') {
addBuildLintViolation('WARs must be published', call)
.insertAfter(call, "apply plugin: 'netflix.war-publish'")
}
}
}
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11. 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')) {
addBuildLintViolation('WARs must be published', call)
.insertAfter(bookmark('applyWar'), "apply plugin: 'netflix.war-publish'")
}
}
}
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12. 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')) {
addBuildLintViolation('WARs must be published', call)
.replaceWith(bookmark('applyWar'), "apply plugin: 'netflix.war-publish'")
}
}
}
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13. 4: BECOME GRADLE MODEL AWARE
class 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')) {
addBuildLintViolation('WARs must be published', call)
.insertAfter(
bookmark('lastApplyPlugin'),
"apply plugin: 'netflix.war-publish'"
)
}
}
}
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14. GRADLE LINT IS OUR FIRST
DISTRIBUTED REFACTORING
TOOL.
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15. THE EXPERIMENTAL LOCK PLUGIN IS
ANOTHER EXAMPLE.
github.com/nebula-plugins/lock-
experimental
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16. WE WANT AN
EVENTUALLY CONSISTENT
MONOREPO
THROUGH
DISTRIBUTED REFACTORING.
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17. JAVA POWER ASSERT WAS THE
LEARNING GROUND.
github.com/jkschneider/java-power-assert
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18. THANK YOU.
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