batch.adoc

Batch Applications

A number of questions often arise when people use Spring Batch from within a Spring Boot application. This section addresses those questions.

Specifying a Batch Data Source

By default, batch applications require a DataSource to store job details. Spring Batch expects a single DataSource by default. To have it use a DataSource other than the application’s main DataSource, declare a DataSource bean, annotating its @Bean method with @BatchDataSource. If you do so and want two data sources, remember to mark the other one @Primary. To take greater control, implement BatchConfigurer. See {spring-batch-api}/core/configuration/annotation/EnableBatchProcessing.html[The Javadoc of @EnableBatchProcessing] for more details.

For more info about Spring Batch, see the {spring-batch}[Spring Batch project page].

Running Spring Batch Jobs on Startup

Spring Batch auto-configuration is enabled by adding @EnableBatchProcessing to one of your @Configuration classes.

By default, it executes all Jobs in the application context on startup (see {spring-boot-autoconfigure-module-code}/batch/JobLauncherApplicationRunner.java[JobLauncherApplicationRunner] for details). You can narrow down to a specific job or jobs by specifying spring.batch.job.names (which takes a comma-separated list of job name patterns).

See {spring-boot-autoconfigure-module-code}/batch/BatchAutoConfiguration.java[BatchAutoConfiguration] and {spring-batch-api}/core/configuration/annotation/EnableBatchProcessing.html[@EnableBatchProcessing] for more details.

Running From the Command Line

Spring Boot converts any command line argument starting with -- to a property to add to the Environment, see accessing command line properties. This should not be used to pass arguments to batch jobs. To specify batch arguments on the command line, use the regular format (that is without --), as shown in the following example:

$ java -jar myapp.jar someParameter=someValue anotherParameter=anotherValue

If you specify a property of the Environment on the command line, it is ignored by the job. Consider the following command:

$ java -jar myapp.jar --server.port=7070 someParameter=someValue

This provides only one argument to the batch job: someParameter=someValue.

Storing the Job Repository

Spring Batch requires a data store for the Job repository. If you use Spring Boot, you must use an actual database. Note that it can be an in-memory database, see {spring-batch-docs}job.html#configuringJobRepository[Configuring a Job Repository].