60 lines
2.9 KiB
Plaintext
60 lines
2.9 KiB
Plaintext
[[howto.batch]]
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== Batch Applications
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A number of questions often arise when people use Spring Batch from within a Spring Boot application.
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This section addresses those questions.
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[[howto.batch.specifying-a-data-source]]
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=== Specifying a Batch Data Source
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By default, batch applications require a `DataSource` to store job details.
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Spring Batch expects a single `DataSource` by default.
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To have it use a `DataSource` other than the application’s main `DataSource`, declare a `DataSource` bean, annotating its `@Bean` method with `@BatchDataSource`.
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If you do so and want two data sources, remember to mark the other one `@Primary`.
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To take greater control, implement `BatchConfigurer`.
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See {spring-batch-api}/core/configuration/annotation/EnableBatchProcessing.html[The Javadoc of `@EnableBatchProcessing`] for more details.
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For more info about Spring Batch, see the {spring-batch}[Spring Batch project page].
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[[howto.batch.running-jobs-on-startup]]
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=== Running Spring Batch Jobs on Startup
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Spring Batch auto-configuration is enabled by adding `@EnableBatchProcessing` to one of your `@Configuration` classes.
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By default, it executes *all* `Jobs` in the application context on startup (see {spring-boot-autoconfigure-module-code}/batch/JobLauncherApplicationRunner.java[`JobLauncherApplicationRunner`] for details).
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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).
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See {spring-boot-autoconfigure-module-code}/batch/BatchAutoConfiguration.java[BatchAutoConfiguration] and {spring-batch-api}/core/configuration/annotation/EnableBatchProcessing.html[@EnableBatchProcessing] for more details.
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[[howto.batch.running-from-the-command-line]]
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=== Running From the Command Line
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Spring Boot converts any command line argument starting with `--` to a property to add to the `Environment`, see <<features#features.external-config.command-line-args,accessing command line properties>>.
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This should not be used to pass arguments to batch jobs.
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To specify batch arguments on the command line, use the regular format (that is without `--`), as shown in the following example:
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[source,shell,indent=0,subs="verbatim"]
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----
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$ java -jar myapp.jar someParameter=someValue anotherParameter=anotherValue
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----
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If you specify a property of the `Environment` on the command line, it is ignored by the job.
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Consider the following command:
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[source,shell,indent=0,subs="verbatim"]
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----
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$ java -jar myapp.jar --server.port=7070 someParameter=someValue
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----
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This provides only one argument to the batch job: `someParameter=someValue`.
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[[howto.batch.storing-job-repository]]
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=== Storing the Job Repository
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Spring Batch requires a data store for the `Job` repository.
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If you use Spring Boot, you must use an actual database.
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Note that it can be an in-memory database, see {spring-batch-docs}job.html#configuringJobRepository[Configuring a Job Repository].
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