Is anyone using Google AppEngine Flex for their Grails projects? I'm having trouble getting it built/configured to find the main class at startup. Up until now I've been using the Java8 environment on AppEngine flex and it was working just fine. 😞

I am not using Google AppEngine, but do you have these in your

build.gradle

file?

application {
    mainClass.set("com.yourpackage.Application")
}

springBoot {
    mainClass.set("com.yourpackage.Application")
}

Interesting... not exactly. I have:

springBoot {
    mainClassName = "sourcingpro.Application"
}

I'll try your example.

Ok, it looks like

mainClassName

was deprecated in favor of

mainClass

in Spring Boot 2.4.0 and was scheduled for removal in 2.6.0. So you are on something pre 2.6. I'd experiment with the application gradle plugin config. It also changed from

mainClassName

to

mainClass

at some point. that's my last guess

application {

mainClassName = "sourcingpro.Application"

}

or

application {

mainClass = "sourcingpro.Application"

}

Could not find method application()

The classNotFound error I'm getting is on the server, as it's unpacking the build and attempting to run it. The config file for the server (app.yaml) is specifying the entrypoint class but it can't find it so I'm wondering if it's something to do with the .war file not being populated correctly. It looks like AppEngine, in the move from Java8 to Java11 runtimes now expects the deployment to have its own Jetty server (rather than provide one in the environment) so there are rather more moving parts to this than I thought. What do most folks use for deploying their projects? GCP? AWS? Complete containers, PaaS? Curious...

For AWS Elastic Beanstalk I use the war file from build/lib generated by

grails prod package

or

gradle -Dgrails.env=prod assemble

AWS has an option with Tomcat or without. I use the one without and it executes the app with

java -jar admin.war

https://docs.grails.org/6.2.0/guide/single.html#_runnable_war_or_jar_file I also have a custom gradle task to put the war in a zip file with some aws specific config, but that is not required for it to run the war.

Thanks James. That's where I'm heading but struggling to get AppEngine to find the

.war

and the

main()

class. I'm missing some key instruction somewhere...