Spring Shell: Is it possible to start spring shell at runtime on demand

Question

I am runing a spring-boot app as a backend application within a docker container. I want to be able to exec in a container and start a shellMethod to execute some admin stuff. Is it possible start and stop a shell session within a container at runtime?

Answer 1

Spring Shell provides the interactive shell, and the non-interactive mode.

Assuming Spring Boot 3.0.0 and Spring Shell 3.0.0-M3 or newer:

If you have a command like this:

@ShellComponent
public class Cli {

    @ShellMethod("Hello world")
    public String hello(@ShellOption(defaultValue = "world") String arg1){
        return "Hello " + arg1 + "!!";
    }
}

and you create demo:0.0.1-SNAPSHOT using the spring boot maven plugin, for example:

./mvnw -Pnative clean spring-boot:build-image -DskipTests

You can execute commands directly against that docker image, like so:

$ docker run -it demo:0.0.1-SNAPSHOT hello FishingIsLife

To get:

Hello FishingIsLife

So you don't need to start/stop a shell session, just use the non-interactive mode of Spring Shell.