This is a sample standalone Java batch-processing application. The batch job contains a single chunk-type step that reads a list of numbers by chunks and prints them to the console. The 2 batch artifacts used in this application are:
-
arrayItemReader: implemented injberet-support, reads a list of objects configured in job xml -
mockItemWriter: implemented injberet-support, writes the output to the console or other destinations
mvn clean install
mvn integration-test
# run with the default configuration in pom.xml
mvn exec:java
# run with job xml
mvn exec:java -Dexec.arguments="simple.xml"
# run with job xml and job parameters
mvn exec:java -Dexec.arguments="simple.xml jobParam1=x jobParam2=y jobParam3=z"
When building this application in OpenShift cloud platform, the openshift profile
defined in pom.xml will be used. The difference between the default and openshift
profile is that the latter will package the entire application and its transitive
dependencies as an executable uber jar.
This process happens automatically when you build and deploy it to OpenShift
with S2I. To build and run it locally with openshift profile:
mvn clean install -Popenshift
java -jar target/jberet-simple.jar simple.xml jobParam1=x jobParam2=y
# log into your OpenShift account
oc login https:xxx.openshift.com --token=xxx
# create a new project, if there is no existing projects
oc new-project <projectname>
# We wil use `openjdk18-openshift` image stream. Check if it is available in the current project
oc get is
# If `openjdk18-openshift` is not present, import it
oc import-image my-redhat-openjdk-18/openjdk18-openshift --from=registry.access.redhat.com/redhat-openjdk-18/openjdk18-openshift --confirm
# create a new application (with default name)
oc new-app openjdk18-openshift~https://github.com/jberet/jberet-simple.git
# or create a new application with custom name
oc new-app openjdk18-openshift~https://github.com/jberet/jberet-simple.git --name=hello-batch
# check status
oc status
# list pods, and get logs for the pod associated with the application:
oc get pods
oc logs jberet-simple-1-kpvqn
From the above log output, you can see that the application has been successfully built and deployed to OpenShift online. Alternatively, you can perform all of the above operations in OpenShift online web console.
Next, we will see how to launch the above batch job from OpenShift command line (oc).
First, create a yaml file (simple.yaml) to describe the Kubernetes job configuration:
apiVersion: batch/v1
kind: Job
metadata:
name: simple
spec:
parallelism: 1
completions: 1
template:
metadata:
name: simple
spec:
containers:
- name: jberet-simple
image: docker-registry.default.svc:5000/pr/jberet-simple
command: ["java", "-jar", "/deployments/jberet-simple.jar", "simple.xml", "jobParam1=x", "jobParam2=y"]
restartPolicy: OnFailure
Then, run the following command to tell OpenShift to launch the job execution:
/Users/cfang/dev/jberet-simple > oc create -f simple.yaml
job.batch "simple" created
/Users/cfang/dev/jberet-simple > oc get jobs
NAME DESIRED SUCCESSFUL AGE
simple 1 0 4s
/Users/cfang/dev/jberet-simple > oc get jobs
NAME DESIRED SUCCESSFUL AGE
simple 1 1 12m
/Users/cfang/dev/jberet-simple > oc get pods
NAME READY STATUS RESTARTS AGE
intro-jberet-6-s94h2 1/1 Running 0 1d
jberet-simple-5-build 0/1 Completed 0 11h
jberet-simple-6-build 0/1 Completed 0 8h
jberet-simple-6-wwjm7 0/1 CrashLoopBackOff 105 8h
postgresql-5-sbfm5 1/1 Running 0 1d
simple-mpq8h 0/1 Completed 0 8h
/Users/cfang/dev/jberet-simple > oc logs simple-mpq8h > /tmp/simple-mpq8h.log
/Users/cfang/dev/jberet-simple > oc delete job simple
job.batch "simple" deleted
First, create a yaml file (simple-cron.yaml) to define the Kubernetes crob job spec.
The cron expression */1 * * * * specifies running the batch job every minute.
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: simple-cron
spec:
successfulJobsHistoryLimit: 3
failedJobsHistoryLimit: 1
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: simple-cron
image: docker-registry.default.svc:5000/pr/jberet-simple
command: ["java", "-jar", "/deployments/jberet-simple.jar", "simple.xml", "jobParam1=x", "jobParam2=y"]
restartPolicy: OnFailure
Then, run the following commands to tell OpenShift to schedule the job executions:
$ oc create -f simple-cron.yaml
cronjob.batch "simple-cron" created
$ oc get cronjobs
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
simple-cron */1 * * * * False 0 <none> 7s
# Get status of a specific cron job
$ oc get cronjob simple-cron
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
simple-cron */1 * * * * False 0 <none> 24s
# Get continuous status of a specific cron job with --watch option
$ oc get cronjob simple-cron --watch
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
simple-cron */1 * * * * False 0 <none> 33s
simple-cron */1 * * * * False 1 7s 46s
simple-cron */1 * * * * False 0 37s 1m
$ oc get pods
NAME READY STATUS RESTARTS AGE
postgresql-5-sbfm5 1/1 Running 0 27d
simple-cron-1536609780-fmrhf 0/1 ContainerCreating 0 1s
simple-mpq8h 0/1 Completed 0 26d
$ oc logs simple-cron-1536609780-fmrhf
$ oc delete cronjobs/simple-cron
cronjob.batch "simple-cron" deleted
# Another variation of the delete command:
$ oc delete cronjob simple-cron
cronjob.batch "simple-cron" deleted
JBERET-349 Integrate JBeret with openshift scheduled job capability
JBERET-448 Move test-apps/simple to its own repo
JBERET-449 Support batch job execution with OpenShift cron job scheduling mechanism