Gradle Copy task always UP-TO-DATE - gradle

Question

I've seen this question posted numerous times, but I've not yet found an answer that matches my specific use case.
I'm created a bunch of config files from a template, after iterating over a config file containing environment properties.
The problem is that if I amend src/properties/ENV.gradle with some new values, it's ignored when I call the task on the basis that it's already "UP-TO-DATE". I'm not using doFirst or doLast, which is one of the common reasons this happens.
My workaround so far is to include
outputs.upToDateWhen { false }
which forces the config files to be recreated every single time regardless of what Gradle calculates, but it feels like an awful hack. Is there a better way?
Here's the code:
task createConfigs
def addTemplateTasks(aProject, env, config) {
aProject.with {
task "templateCopy_${env}"(type: Copy) {
from "src/templates"
include "server.config.template"
into "${buildDir}"
rename { file -> "server.config.${env}" }
expand(regionConfig)
}
createConfigs.dependsOn "templateCopy_${env}"
}
}
def envFile = new File("${project.projectDir}/src/properties/ENV.gradle")
def envConfig = new ConfigSlurper().parse(envFile.text)
envConfig.each { env, config ->
addTemplateTasks(project, env, config)
}
SOLUTION:
My case was a bit specific in that I was expecting the Copy task to notice "config" changing, without telling it explicitly care about it (see accepted answer below). Here's the change that fixed the problem:
def addTemplateTasks(aProject, env, config) {
aProject.with {
task "templateCopy_${env}"(type: Copy) {
inputs.property("environmentConfig", config)
The first arg (in quotes) is the name for this property, the second is the actual value.
Now, when I change a property in the ENV.gradle file and run "gradle -i", I see this:
Task ':component-foo:templateCopy_DEV' is not up-to-date because:
Value of input property 'environmentConfig' has changed for task ':component-foo:templateCopy_DEV'

Answer 1

The only input of your copy task, is the src/templates directory. Unless the content of src/templates doesn't change an the copied outputs are still present, your task will be considered UP-TO-DATE.
The problem is that your copy task actually has a second input which Gradle doesn't know about: Your config/regionConfig object.
Try to add the config object (or a hash of the objects values) to the inputs of the copy task using inputs.property or inputs.properties.