This project contains 2 modules to deploy on Cloud Foundry. The spring-scheduled module uses the @Scheduled annotation, and the pcf-scheduler module uses the PCF Scheduler service.
Run the following command to build the 2 modules and to generate jars ready to deploy.
mvn clean package
Before deploying, you have to create a new Scheduler for PCF service available from the Marketplace.
cf create-service scheduler-for-pcf standard pcf-scheduler
You can deploy the each modules manually or use the provided manifest.yml deployment file to deploy both of them. The pcf-scheduler app will bind to the newly pcf-scheduler service. Great names right? ;)
cf push
The code runs great and every minutes as expected. But once you have more than one instance (and you should), each instances are executing the scheduled task
2018-02-28T10:58:00.00-0500 [APP/PROC/WEB/0] OUT IP Address: 515d00e6-def4-4d08-6745-7bf9/10.255.22.200, Thread: pool-1-thread-1, Time: 15:58:00.001
2018-02-28T10:58:00.00-0500 [APP/PROC/WEB/1] OUT IP Address: 50c8060c-bb62-474a-69e8-7f43/10.251.58.164, Thread: pool-1-thread-1, Time: 15:58:00.001
2018-02-28T10:59:00.00-0500 [APP/PROC/WEB/0] OUT IP Address: 515d00e6-def4-4d08-6745-7bf9/10.255.22.200, Thread: pool-1-thread-1, Time: 15:59:00.001
2018-02-28T10:59:00.00-0500 [APP/PROC/WEB/1] OUT IP Address: 50c8060c-bb62-474a-69e8-7f43/10.251.58.164, Thread: pool-1-thread-1, Time: 15:59:00
2018-02-28T11:00:00.00-0500 [APP/PROC/WEB/0] OUT IP Address: 515d00e6-def4-4d08-6745-7bf9/10.255.22.200, Thread: pool-1-thread-1, Time: 16:00:00.001
2018-02-28T11:00:00.00-0500 [APP/PROC/WEB/1] OUT IP Address: 50c8060c-bb62-474a-69e8-7f43/10.251.58.164, Thread: pool-1-thread-1, Time: 16:00:00.001
The above sample has 2 running instances and you can notice in the logs that both of them are running the job. You can avoid that by using the Scheduler for PCF service in the next example.
Once the pcf-scheduler app is deployed, you can add a cron job to run the code every minute. You will need to install the CF cli plugin.
cf create-job pcf-scheduler my-demo ".java-buildpack/open_jdk_jre/bin/java -cp ./BOOT-INF/classes ninja.spring.pcfscheduler.Scheduler"
cf schedule-job my-demo "0/1 * ? * *"
The first command will create a job with the command to execute. Let me know if you find a more elegant way :) The second command will associate a cron schedule to the previously created job. Notice the syntax? Somehow it is NOT a regular cron expression and there is no documentation about it (cron).
2018-03-01T11:58:00.72-0500 [CELL/0] OUT Creating container
2018-03-01T11:58:01.48-0500 [CELL/0] OUT Successfully created container
2018-03-01T11:58:06.24-0500 [APP/TASK/08e8c101-f36c-4d21-99e5-9976e7fc6855-|-051838d5-9010-44d5-8a79-8196276211e6/0] OUT IP Address: 91c6f6a4-0ba0-4940-9f86-a849e734328c/10.255.210.170, Thread: main, Time: 16:58:06.226
2018-03-01T11:58:06.25-0500 [APP/TASK/08e8c101-f36c-4d21-99e5-9976e7fc6855-|-051838d5-9010-44d5-8a79-8196276211e6/0] OUT Exit status 0
2018-03-01T11:58:06.27-0500 [CELL/0] OUT Stopping instance 91c6f6a4-0ba0-4940-9f86-a849e734328c
2018-03-01T11:58:06.27-0500 [CELL/0] OUT Destroying container
2018-03-01T11:58:07.03-0500 [CELL/0] OUT Successfully destroyed container
2018-03-01T11:59:00.76-0500 [CELL/0] OUT Creating container
2018-03-01T11:59:01.32-0500 [CELL/0] OUT Successfully created container
2018-03-01T11:59:06.80-0500 [APP/TASK/08e8c101-f36c-4d21-99e5-9976e7fc6855-|-051838d5-9010-44d5-8a79-8196276211e6/0] OUT IP Address: 2033bbff-65c4-426e-a07a-ceaef072a8b5/10.249.187.45, Thread: main, Time: 16:59:06.793
2018-03-01T11:59:06.81-0500 [APP/TASK/08e8c101-f36c-4d21-99e5-9976e7fc6855-|-051838d5-9010-44d5-8a79-8196276211e6/0] OUT Exit status 0
2018-03-01T11:59:06.82-0500 [CELL/0] OUT Stopping instance 2033bbff-65c4-426e-a07a-ceaef072a8b5
2018-03-01T11:59:06.82-0500 [CELL/0] OUT Destroying container
2018-03-01T11:59:07.33-0500 [CELL/0] OUT Successfully destroyed container
Notice the creation of a new container that will execute the code only once every minute.
If you want to learn more, check out my blog