3 Launching
This chapter introduces how to launch a Ratpack application, and the associated launch time configuration.
3.1 Launch configuration
To launch a Ratpack application, you must create a LaunchConfig
. This can then be used with the RatpackServerBuilder
method to create a RatpackServer
that can then be started.
Note that one of the LaunchConfig
object’s responsibilities is to provide a HandlerFactory
implementation. This factory is responsible for creating the handler that is effectively the Ratpack application. See the chapter on handlers for more details.
One option for building a LaunchConfig
is to use the LaunchConfigBuilder
. Another option is to use LaunchConfigs
which is able to build a launch config from system properties and a properties file.
3.2 RatpackMain
The RatpackMain
class is a convenient entry point (i.e. main class) that bootstraps a Ratpack application. When building with Gradle, this is the default main class.
The minimum requirement for launching a RatpackMain
based application, is to ensure there is a ratpack.properties
file on the JVM classpath that indicates the application HandlerFactory
…
handlerFactory=org.my.HandlerFactory
All aspects of the LaunchConfig can be specified in this properties file. Aspects can also be environmentally overridden by JVM system properties. See RatpackMain
for details.