Scheduling / Quartz integration for Dropwizard
This plugin integrates the quartz scheduler with dropwizard and allows you to easily create background jobs, which are not bound to the HTTP request-response cycle.
Quartz creates a threadpool on application startup and uses it for background jobs.
There are four different types of jobs:
- Jobs run on application start for initial setup (could also be done via a managed instance in dropwizard)
- Jobs run at application stop before the application is closed (could also be done via managed instance in dropwizard)
- Jobs which are repeated after a certain time interval
- Jobs which need to run at a specific time, via a cron-like expression
Using maven central repository
dropwizard jobs can be used with maven.
It is located in Central Repository. https://search.maven.org/
Add to your pom:
<dependency>
<groupId>io.github.dropwizard-jobs</groupId>
<artifactId>dropwizard-jobs-core</artifactId>
<version>6.0.0</version>
</dependency>
Installing the bundle from source code
git clone https://github.com/dropwizard-jobs/dropwizard-jobs
cd dropwizard-jobs
./mvn install
After installing the plugin locally you can include it in your pom.xml
<dependency>
<groupId>io.github.dropwizard-jobs</groupId>
<artifactId>dropwizard-jobs-core</artifactId>
<version>$VERSION</version>
</dependency>
Activating the bundle: Configuration
Your Dropwizard application configuration class must extend JobConfiguration:
public class ApplicationConfiguration extends JobConfiguration {
...
}
Activating the bundle: Initialization
In your application’s initialize method, call bootstrap.addBundle(new JobsBundle(<List of jobs>)):
@Override
public void initialize(Bootstrap<MyConfiguration> bootstrap) {
SomeDependency dependency = new Dependency();
Job startJob = new StartupJob();
Job stopJob = new StopJob();
Job everyJob = new EveryTestJob(dependency);
bootstrap.addBundle(new JobsBundle(new ArrayList<>(startJob, stopJob, everyJob)));
}
Available job types
The @OnApplicationStart annotation triggers a job after the quartz scheduler is started
@OnApplicationStart
public class StartupJob extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// logic run once on application start
}
}
The @OnApplicationStop annotation triggers a job when the application is stopped. Be aware that it is not guaranteed that this job is executed, in case the application is killed.
@OnApplicationStop
public class StopJob extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// logic run once on application stop
}
}
The @Every annotation first triggers a job after the quartz scheduler is started and then every n times, as it is configured. You can use a number and a time unit, which can be one of “s” for seconds, “m” or “mn” or “min” for minutes, “h” for hours, “d” for days and “ms” for milliseconds.
Use in conjunction with @DelayStart to delay the first invocation of this job.
@Every("1s")
public class EveryTestJob extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// logic run every time and time again
}
}
The @DelayStart annotation can be used in conjunction with @Every to delay the start of the job. Without this, all the @Every jobs start up at the same time when the scheduler starts.
@DelayStart("5s")
@Every("1s")
public class EveryTestJobWithDelayedStart extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// logic run every time and time again
}
}
The @On annotation allows one to use cron-like expressions for complex time settings. You can read more about possible cron expressions at https://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/tutorial-lesson-06.html
This expression would run on Mondays at 1pm, Los Angeles time. If the optional parameter timeZone is not set system default will be used.
@On(value = "0 0 13 ? * MON", timeZone = "America/Los_Angeles")
public class OnTestJob extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// logic run via cron expression
}
}
By default a class can only be scheduled once in the jobs bundle, this can be overridden by setting a unique groupName to the instance.
@Every("15m")
public class GroupNameJob extends Job {
public GroupNameJob(String groupName) {
super(groupName);
}
}
Using dropwizard-jobs in a Clustered Environment
By default, dropwizard-jobs is designed to be used with an in-memory Quartz scheduler. If you wish to deploy it in a clustered environment that consists of more than one node, you’ll need to use a scheduler that has some sort of persistence. You can either add a file called quartz.properties to your classpath or you can provide the quartz configuration in your Dropwizard configuration file. The content of the quartz element is passed to the Quartz scheduler directly (so you can take the properties from the official docs). If you’d like to add the config to your Dropwizard configuration file, you need to override the getQuartzConfiguration() method in your application’s configuration. You can set the map to DefaultQuartzConfiguration.get().
See the full Quartz configuration reference at https://www.quartz-scheduler.org/documentation/quartz-2.x/configuration/
[...]
quartz:
org.quartz.scheduler.instanceName: "scheduler"
org.quartz.scheduler.instanceId: "AUTO"
org.quartz.scheduler.skipUpdateCheck: "true"
org.quartz.threadPool.class: "org.quartz.simpl.SimpleThreadPool"
org.quartz.threadPool.threadCount: "10"
org.quartz.threadPool.threadPriority: "5"
org.quartz.jobStore.misfireThreshold: "60000"
org.quartz.jobStore.class: "org.quartz.impl.jdbcjobstore.JobStoreTX"
org.quartz.jobStore.driverDelegateClass: "org.quartz.impl.jdbcjobstore.StdJDBCDelegate"
org.quartz.jobStore.useProperties: "false"
org.quartz.jobStore.dataSource: "myDS"
org.quartz.jobStore.tablePrefix: "QRTZ_"
org.quartz.jobStore.isClustered: "true"
org.quartz.dataSource.myDS.driver: "com.mysql.cj.jdbc.Driver"
org.quartz.dataSource.myDS.URL: "jdbc:mysql://localhost:3306/quartz"
org.quartz.dataSource.myDS.user: "fami"
org.quartz.dataSource.myDS.password: "ageClXl5mrSg"
org.quartz.dataSource.myDS.maxConnections: "5"
org.quartz.dataSource.myDS.validationQuery: "select 1"
When you do this, dropwizard-jobs will ensure that only one instance of each job is scheduled, regardless of the number of nodes in your cluster by using the fully-qualified class name of your job implementation as the name of your job. For example, if your job implementation resides in a class called MyJob, which in turn is located in the package com.my.awesome.web.app, then the name of your job (so far as Quartz is concerned) will be com.my.awesome.web.app.MyJob.
If you wish to override the default name that dropwizard-jobs assigns to your job, you can do so by setting the jobName property in the @Every or @On annotation like so:
package com.my.awesome.web.app
/**
* This job will be given the name "MyJob" instead of the name "com.my.awesome.web.app.MyJob"
*/
@Every(value="5s", jobName="MyJob")
public class MyJob extends Job {
@Override
public void doJob(JobExecutionContext context) throws JobExecutionException {
// do some work here
}
}
This property is not supported in the @OnApplicationStart or @ApplicationStop annotations, as they are designed for jobs that will fire reliably when Dropwizard starts or stops your web application. As such, jobs annotated with @OnApplicationStart or @OnApplicationStop will be given unique names, and will be fired according to schedule on every node in your cluster.
Configuring jobs in the Dropwizard Config File
The period for @Every and @On jobs can be read from the dropwizard config file instead of being hard-coded. The YAML looks like this:
jobs:
myJob: 10s
myOtherJob: 20s
cronJob: "0 0/3 0 ? * * * [Europe/London]"
For @On jobs, the cron expression can have an optional timezone specified in square brackets.
If no timezone is given, the de.spinscale.dropwizard.jobs.timezone system property will be used,
otherwise your server’s default timezone will apply.
Where MyJob and MyOtherJob are the names of Job classes in the application. In the Configuration class add the corresponding property:
@JsonProperty("jobs")
private Map<String , String> jobs;
public Map<String, String> getJobs() {
return jobs;
}
public void setJobs(Map<String, String> jobs) {
this.jobs = jobs;
}
Then the @Every annotation can be used without a value, its value is set from the configuration:
@Every
public class MyJob extends Job {
...
}
An alternative label to the class name can also be specified:
@Every("${foobar}")
public class MyJob extends Job {
...
}
The same can be done with the @On annotation as well, as second option to cron-base jobs configuration
An alternative label to the class name can also be specified:
@On("${cronJob}")
public class MyJob extends Job {
...
}
So long as there is a matching property in the YAML:
jobs:
foobar: 10s
Limitations
- Configuration mechanism is still in early stages. Might be enhanced in the future.
Thanks
- The playframework 1.x for the idea of simple annotations at Job classes