Gradle cannot find plugin declared in buildscript - gradle

Question

I'm trying to factor out common Gradle tasks in a reusable file. Here is an excerpt of a build-root.gradle file:
buildscript {
// Repository declaration
ext {
isSnapshot = version.endsWith("-SNAPSHOT")
repos = {
def mavenRepo = { repoName, repoUrl ->
maven {
credentials {
username System.env.<some env var>
password System.env.<some env var>
}
name repoName
url repoUrl
}
}
mavenLocal()
mavenRepo('repo1', 'https://repo1.url')
mavenRepo('repo2', 'https://repo2.url')
mavenRepo('repo3', 'https://repo3.url')
}
}
// Versions and libraries declaration
ext {
versions = [
... some stuff
// Gradle
gradleRelease : '2.8.1',
... more stuff
]
libs = [
... some stuff
// Gradle
gradleRelease : "net.researchgate:gradle-release:$versions.gradleRelease",
... more stuff
]
}
repositories repos
dependencies {
classpath libs.gradleRelease
}
apply plugin: 'net.researchgate.release'
}
... more common stuff
The idea is for subprojects to apply from that file and get all the goodies from it.
On the "apply plugin" line I get the following error - > Plugin with id 'net.researchgate.release' not found.
I printed the libs.gradleRelease string, it looks fine: net.researchgate:gradle-release:2.8.1
We are currently using Gradle 5.2.1, but I also tried 6.0.1 - same error. Any ideas why it can't find the plugin? BTW, this is not exclusive to this particular plugin, I tried others and still get the same error.

Answer 1

After pulling whatever was left of my hair and banging my head against the wall, I came across this => https://discuss.gradle.org/t/how-do-i-include-buildscript-block-from-external-gradle-script/7016
Relevant comment from #Peter_Niederwieser:
"Secondly, externalizing a build script block into a script plugin isn’t supported. (It’s a tough problem, and can’t think of a good way to implement this.) You may have to live with some duplication, at least for the time being. Remember that dependencies specified in a project’s ‘buildscript’ block are visible to all subprojects. Hence, as long as you don’t need dependencies to be available in a script plugin, you just need to declare them in the root project’s build script."
Which is exactly what I was trying to do. I'm not going to curse here...