how to select which spring batch job to run based on application argument - spring boot java config

Just set the "spring.batch.job.names=myJob" property. You could set it as SystemProperty when you launch your application (-Dspring.batch.job.names=myjob). If you have defined this property, spring-batch-starter will only launch the jobs, that are defined by this property.

To run the jobs you like from the main method you can load the the required job configuration bean and the JobLauncher from the application context and then run it:

@ComponentScan
@EnableAutoConfiguration
public class ApplicationWithJobLauncher {

    public static void main(String[] args) throws BeansException, JobExecutionAlreadyRunningException, JobRestartException, JobInstanceAlreadyCompleteException, JobParametersInvalidException, InterruptedException {

        Log log = LogFactory.getLog(ApplicationWithJobLauncher.class);

        SpringApplication app = new SpringApplication(ApplicationWithJobLauncher.class);
        app.setWebEnvironment(false);
        ConfigurableApplicationContext ctx= app.run(args);
        JobLauncher jobLauncher = ctx.getBean(JobLauncher.class);
        JobParameters jobParameters = new JobParametersBuilder()
            .addDate("date", new Date())
            .toJobParameters();  

        if("1".equals(args[0])){
            //addNewPodcastJob
            Job addNewPodcastJob = ctx.getBean("addNewPodcastJob", Job.class);          
            JobExecution jobExecution = jobLauncher.run(addNewPodcastJob, jobParameters);                   
        } else {
            jobLauncher.run(ctx.getBean("newEpisodesNotificationJob",  Job.class), jobParameters);   

        } 

        System.exit(0);
    }
}

What was causing my lots of confusion was that the second job were executed, even though the first job seemed to be "picked up" by the runner... Well the problem was that in both job's configuration file I used standard method names writer(), reader(), processor() and step() and it used the ones from the second job that seemed to "overwrite" the ones from the first job without any warnings... I used though an application config class with @EnableBatchProcessing(modular=true), that I thought would be used magically by Spring Boot :

@Configuration
@EnableBatchProcessing(modular=true)
public class AppConfig {

    @Bean
    public ApplicationContextFactory addNewPodcastJobs(){
        return new GenericApplicationContextFactory(AddPodcastJobConfiguration.class);
    }

    @Bean
    public ApplicationContextFactory newEpisodesNotificationJobs(){
        return new GenericApplicationContextFactory(NotifySubscribersJobConfiguration.class);
    }    

}

I will write a blog post about it when it is ready, but until then the code is available at https://github.com/podcastpedia/podcastpedia-batch (work/learning in progress)..