Shared #Input properties on Gradle Plugin tasks, ideally nested config - groovy

Question

My gradle plugin generates a number of tasks that have shared configuration. This configuration needs to be marked as #Input, so when it's changed, the task is marked as stale and re-evaluated. I'm finding it challenging to share the config when it should apply to multiple tasks. I'm using avoiding project.afterEvaluate to allow incremental compilation. This example is a reduced version of what I currently have:
Current Plugin Code:
class MyPluginTaskOne extends DefaultTask {
#Input config = "default"
#TaskAction
public void action() {
// something that depends on config
}
}
class MyPluginTaskTwo extends DefaultTask {
#Input config = "default"
#TaskAction
public void action() {
// something that depends on config
}
}
class MyPluginExtension {
// blank for now
}
class MyPlugin implements Plugin<Project> {
void apply(Project project) {
project.extensions.create("myPluginConfig", MyPluginExtension)
project.tasks.create(name: 'myPluginTaskOne', type: MyPluginTaskOne) {}
project.tasks.create(name: 'myPluginTaskTwo', type: MyPluginTaskTwo) {}
}
}
Current Config:
Currently the best way I have to share state is the following. This has the problem is that it's error prone and doesn't automatically sharing the setting:
apply plugin: MyPlugin
// Kludgy way of sharing configuration across two tasks:
def sharedConfig = "SHARED-CONFIG"
myPluginTaskOne {
config sharedConfig
}
myPluginTaskTwo {
config sharedConfig
}
Preferred Config:
What I'd like to do is a configuration something like the following, but with all the benefits of tracking #Input dependencies and up-to-date tests.
myPluginConfig {
config "SHARED-CONFIG"
// myPluginTaskOne and myPluginTaskTwo both gets automatic
// 'SHARED-CONFIG' through Gradle
}
It appears that you can automatically add dependencies between tasks (see below). Is it possible to configure only the first task and then have that #Input trickle down to the #Input on the second task?
Let us try removing the task dependencies by relying on how CopySpec.from() evaluates arguments with Project.files(). Gradle can automatically add task dependencies for us. This also adds the output of the generator task as inputs to the zip task.
From https://gradle.org/feature-spotlight-incremental-builds/

Answer 1

To build on Mark's comments. Here is an example of a property that applies to all tasks and cannot be overridden (config).
class MyPluginTaskOne extends DefaultTask {
#Input String getConfig() { project.myPluginConfig.config }
#TaskAction
public void action() {
// something that depends on config
}
}
class MyPluginTaskTwo extends DefaultTask {
#Input String getConfig() { project.myPluginConfig.config }
#TaskAction
public void action() {
// something that depends on config
}
}
class MyPluginExtension {
String config
}
class MyPlugin implements Plugin<Project> {
void apply(Project project) {
project.with {
extensions.create("myPluginConfig", MyPluginExtension)
tasks.create(name: 'myPluginTaskOne', type: MyPluginTaskOne) {}
tasks.create(name: 'myPluginTaskTwo', type: MyPluginTaskTwo) {}
}
}
}

Answer 2

The most common convention is to use an extension to do this. It looks like you've started to do this. You would then define the property on the extension, then your plugin would read the extension and set the property on all relevant tasks.
myPluginConfig {
sharedConfig 'value'
}
In your plugin:
def extension = extensions.create("myPluginConfig", MyPluginExtension)
project.afterEvaluate {
// read prop from `extension` and set prop on tasks
}