Document the use of --args to pass arguments to bootRun

[philwebb]

Double check how easy it is to pass arguments to a bootRun application and how profiles can be activated.

[dsyer]

It's the same as "gradle run". Do we want to change that?

[snicoll]

shouldn't we look at the maven plugin as well?

[dsyer]

Yes, it's the same thing really (spring-boot:run is a lot like exec:java).

[philwebb]

This was something @tomaslin mentioned to me. Not sure what the answer is yet, I just wanted to note that is was a pain point.

[tomaslin]

To add a little bit more context, if you read the spring boot documentation, you think that you would be able to pass in command line arguments to bootRun to take advantage of SpringApplication's ability to access them as a property.

However, doing something like

./gradlew -Dserver.port=10100 bootRun

doesn't seem to work, since gradle needs you to explicitly bind the parameters you need.

If you look at the grails-gradle integration, Jon Engelman bypasses this by sending the parameters passed into the grailsArgs environment variable into the application,

gradle -PgrailsArgs='--inplace solr' grails-create-plugin

It is quite tedious to have to change the build.gradle file for every environment variable, and it would be nice if the plugin allowed a mechanism to send command line parameters into the launcher

[snicoll]

For the record, the maven plugin already supports that (kinda). You can run something like this

mvn spring-boot:run -Drun.arguments="--info.foo=bar"

This would add a "foo" property to the /info endpoint. If you need to specify more than one arguments, this gets a bit clunky (notice the comma to separate the arguments)

mvn spring-boot:run -Drun.arguments="--info.foo=bar,--info.version=1.4.5"

This is not coming out of nowhere, the maven-exec-plugin behaves in a similar way. We could use space to separate the arguments but this would bring other problems.

I think it would be nice to add a specific property there to be be able to specify the profiles to enable for the app.