The Spring Boot gradle plugin provides the bootRun task that allows a
developer to start the application in a “developer mode” without first building
a JAR file and then starting this JAR file. Thus, it’s a quick way to test
the latest changes you made to the codebase.
Sadly, most applications cannot be started or would not work correctly without
specifying a couple configuration parameters. Spring Boot supports such
parameters with it’s application.properties file. The parameters in this file
are automatically read when the application is started from a JAR
and passed to the application.
The bootRun task also allows to define such properties.
The common way of doing this is like this in the build.gradle file:
bootRun {
jvmArgs =
[
"-DmyApp.myParam1=value1",
"-DmyApp.myParam2=value2"
]
}
However, if your are working at the codebase together with other developers,
each developer may want to test different use cases and needs different
configuration values. She would have to edit the build.gradle each time.
And each time she checks in changes to the codebase, she has to check if
the build.gradle file should really be checked in. Which is not what we want.
The solution to this problem is a specific properties file for each developer’s
local environment that is not checked into the VCS.
Let’s call it local.application.properties. In this file, put your applications
configuration parameters just as you would in a real application.properties file.
To make the bootRun task load these properties, add the following snippet to your
build.gradle:
def Properties localBootRunProperties() {
Properties p = new Properties();
p.load(new FileInputStream(
file(project.projectDir).absolutePath + "/local.application.properties"))
return p;
}
Then, in your bootRun task, fill the systemProperties attribute as follows:
bootRun {
doFirst {
bootRun.systemProperties = localBootRunProperties()
}
}
The call to localBootRunProperties() is put into the doFirst closure so that
it gets executed only when the task itself is executed. Otherwise event all other tasks
would fail with a FileNotFoundException if the properties file is not found
instead of only the bootRun task.
