Building NodeJS using Gradle - node.js

Question

I'm very new to Gradle. I started reading about it yesterday. I found an example build.gradle that builds a node application. I'm a little bit confused in the contents of the file. I'm not sure which ones are reserved or predefined words. One of the strings is node. It wasn't used somewhere but I figured out it was needed by the node plugin.
buildscript {
repositories {
mavenCentral()
maven {
url 'https://plugins.gradle.org/m2/'
}
}
dependencies {
classpath 'com.moowork.gradle:gradle-node-plugin:1.2.0'
}
}
apply plugin: 'base'
apply plugin: 'com.moowork.node' // gradle-node-plugin
node {
/* gradle-node-plugin configuration
https://github.com/srs/gradle-node-plugin/blob/master/docs/node.md
Task name pattern:
./gradlew npm_<command> Executes an NPM command.
*/
// Version of node to use.
version = '10.14.1'
// Version of npm to use.
npmVersion = '6.4.1'
// If true, it will download node using above parameters.
// If false, it will try to use globally installed node.
download = true
}
npm_run_build {
// make sure the build task is executed only when appropriate files change
inputs.files fileTree('public')
inputs.files fileTree('src')
// 'node_modules' appeared not reliable for dependency change detection (the task was rerun without changes)
// though 'package.json' and 'package-lock.json' should be enough anyway
inputs.file 'package.json'
inputs.file 'package-lock.json'
outputs.dir 'build'
}
// pack output of the build into JAR file
task packageNpmApp(type: Zip) {
dependsOn npm_run_build
baseName 'npm-app'
extension 'jar'
destinationDir file("${projectDir}/build_packageNpmApp")
from('build') {
// optional path under which output will be visible in Java classpath, e.g. static resources path
into 'static'
}
}
// declare a dedicated scope for publishing the packaged JAR
configurations {
npmResources
}
configurations.default.extendsFrom(configurations.npmResources)
// expose the artifact created by the packaging task
artifacts {
npmResources(packageNpmApp.archivePath) {
builtBy packageNpmApp
type 'jar'
}
}
assemble.dependsOn packageNpmApp
String testsExecutedMarkerName = "${projectDir}/.tests.executed"
task test(type: NpmTask) {
dependsOn assemble
// force Jest test runner to execute tests once and finish the process instead of starting watch mode
environment CI: 'true'
args = ['run', 'test']
inputs.files fileTree('src')
inputs.file 'package.json'
inputs.file 'package-lock.json'
// allows easy triggering re-tests
doLast {
new File(testsExecutedMarkerName).text = 'delete this file to force re-execution JavaScript tests'
}
outputs.file testsExecutedMarkerName
}
check.dependsOn test
clean {
delete packageNpmApp.archivePath
delete testsExecutedMarkerName
}
Also, how is the build.gradle parsed? I'm also wondering how it is able to magically download node and npm tools.

Answer 1

This is a very general synopsis:
Gradle aims to hide away the logic from developers.
Most *.gradle files contain configuration blocks (closures) to specify HOW logic should run.
Plugins augment gradle with more configurable logic.
Also, 'convention over configuration' is a practice emphasize in gradle and its plugins, providing sensible defaults to minimize developers' configuration efforts.
The com.moowork.node plugin is configured through the node extension block.
Extension blocks are gradle's way to allow plugins to add more 'reserved' words to the standard gradle model.
The download = true configuration tells the plugin to download node (version = '10.14.1') and nmp (npmVersion = '6.4.1') in your project's root (unless you override its defaults as well).
The download of these tools will occur when any of the plugin's task is invoked.
Hope this helps.

Answer 2

In your snippet only true is keyword, the other things are methods or getters coming from Gradle or Node JS plugin:
apply plugin: ... is a method from org.gradle.api.Project.apply(java.util.Map<String, ?>)
node is a method autogenerated by Gradle with signature void node(Closure<com.moowork.gradle.node.NodeExtension>) (method accepting a code block), see https://github.com/srs/gradle-node-plugin/blob/master/src/main/groovy/com/moowork/gradle/node/NodeExtension.groovy
node { version = ... } - version, npmVersion are fields from NodeExtension class
other things similarly, everything is a method or a field. If you're using IntelliJ, use Ctrl+mouse click to navigate to the originating method/field declaration.