How to apply javaagent to gretty plugin based on gradle command line? - gradle

Question

The question is specific, but it's more of a general 'how to do this in gradle' question.
I have a demo java web app that I can run using the gretty plugin. I would like to selectively control whether a javaagent is applied to the jvmArgs of the gretty process based on a command line flag. The agent jar location is known by getting its path from a dummy configuration:
configurations {
agent
}
dependencies {
...
agent group: 'com.foo', name: 'foo-agent', version: '1.0'
}
I know I can access the jar file location using something like:
project.configurations.agent.find { it.name.startsWith("foo-agent") }
How can I selectively apply that to the gretty jvmArgs configuration based on a command line property such as
gradle -PenableAgent

Answer 1

I ended up solving this by creating a task and simply calling it before I run the war:
task agent {
doFirst {
def agentJar = project.configurations.agent.find { it.name.startsWith("foo-agent") }
gretty.jvmArgs << "-javaagent:" + agentJar
}
}
Then I can simply call:
gradle agent appRunWar

Answer 2

In my project I use Spring Instrument as java agent so this was my solution.
You can make appRun task dependent on agent task then no additional gradle run parameter needed.
dependencies {
...
agent 'org.springframework:spring-instrument:4.2.4.RELEASE'
}
configurations {
dev
agent
}
gretty {
...
contextPath = '/'
jvmArgs=[]
springBoot = true
...
}
task agent {
doFirst {
def agentJar = project.configurations.agent.find{it.name.contains("spring-instrument") }
gretty.jvmArgs << "-javaagent:" + agentJar
}
}
project.afterEvaluate {
tasks.appRun.dependsOn agent
}