= Partitioned Job

An example of the usage of the `DeployerPartitionHandler` and
`DeployerStepExecutionHandler` to partition a Spring Batch job.

== Requirements:

* Java 17 or Above

== Build:

[source,shell]
----
./mvnw clean install
----

== Execute:

[source,shell]
----
export SPRING_APPLICATION_JSON='{"spring.datasource.url":"jdbc:mariadb://localhost:3306/<your database>","spring.datasource.password":"<your password>","spring.datasource.username":"<your username>","spring.datasource.driverClassName":"org.mariadb.jdbc.Driver"}'
java -jar target/partitioned-batch-job-3.0.0.jar
----

NOTE: This example will use require a MySql RDBMS repository and currently uses the mariadb jdbc driver to connect.
You can changes this another driver based on your needs.

NOTE: Since this example uses the Spring Cloud Deployer Local to launch the partitions, you will need to establish the datasource settings using the SPRING_APPLICATION_JSON environment property as shown above.

== Dependencies:

A datasource (not in memory) must be configured based on normal Spring Boot conventions
(application.properties, application.yml, environment variables).

== Asynchronous remote partition task launch
Currently partitions are launched sequentially.   To launch them asynchronously set the following environment variables:

* `spring.cloud.task.closecontextEnabled=true`
* `io.spring.asynchronous=true`

NOTE: We need to close the context since the use of ThreadPoolTaskExecutor leaves a thread active thus the app will not terminate.
To close the application appropriately, we will need to set `spring.cloud.task.closecontextEnabled`` to true.

== Running Partitioned sample on Kubernetes
The current sample is set up to run the partitioning using the `local` deployer, so to change this sample so that it work with the `kubernetes` deployer.

=== Changes to the application in order to partition on Kubernetes
. Replace the `spring-cloud-deployer-local` dependency with `spring-cloud-deployer-kubernetes` in the pom.xml.  For example:
+
[source,xml]
----
# Replace
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-deployer-local</artifactId>
			<version>${spring-cloud-deployer}</version>
		</dependency>
# With
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-deployer-kubernetes</artifactId>
			<version>${spring-cloud-deployer}</version>
		</dependency>
----

. Add the following dependency so that we can use docker as a resource:
+
[source,xml]
----
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-deployer-resource-docker</artifactId>
			<version>${spring-cloud-deployer}</version>
		</dependency>
----
. Replace the resource that is used to retrieve the jar from maven with the docker resource to obtain the docker image as follows:
+
[source,java]
----
// Replace
		Resource resource = this.resourceLoader
			.getResource("maven://io.spring.cloud:partitioned-batch-job:3.0.0-SNAPSHOT");
// With
		Resource resource = new DockerResource("partitioned-batch-job:3.0.0-SNAPSHOT");
----
. Build a docker image using the following command:
+
[source,bash]
----
./mvnw spring-boot:build-image
----

=== Notes on when launching this application on Kubernetes

* Be sure to make sure the application has the proper permissions to launch another pod.   For example in Spring Cloud Data Flow be sure to set the `deployment-service-account-name` ot `scdf-sa`.
* When using Spring Cloud Data Flow be sure to set the `entry-point-style` to `boot`.