Stupid simple distributed job scheduling in node, backed by redis.
Bossman combines schedulers and workers into a single concept, which aligns better with most node applications. All of the jobs run with a redis lock, preventing more than once instance from performing a given job at a time.
Bossman is published on
npm, and can be installed simply:
npm install bossman --save
Or if you use Yarn in your project:
yarn add bossman
You can then import the module and use it normally. For more details, see the API documentation.
;// Make sure you name your variables clever things:const fred =connection:host: '127.0.0.1'port: 1234// Set the redis key prefix:prefix: 'bossman:';// Hire for a job.fred;// Hire something as soon as possible:fred;// You can also "qa" work:fred;// Fire a job, this will cancel any pending jobs:fred;// Shut down our instance.fred;
new Bossman(options: Object)
Creates a new bossman instance. All arguments are optional.
options.connection: Used to configure the connection to your redis. This accepts the same arguments that
options.prefix: A string that all redis keys will be prefixed with. Defaults to
options.ttl: The number of milliseconds before a job times out. Setting it will change the maximum duration that jobs can hold a lock. By default, job locks will timeout if a job does not complete in 2000ms.
bossman.hire(jobName: String, jobDefinition: Object)
Schedules recurring work to be done.
jobName: A unique name for the job.
jobDefinition: The job definition can contain three properties:
jobDefinition.work: A function that is invoked to perform the job. If the work is async, this function should return a promise to properly reflect the completion of the job.
jobDefinition.every: A string which describes the interval the job will be run. This can either be a human-friendly string (which will be parsed by the
timestringmodule), or a number reflecting the milliseconds to wait between each job run.
jobDefinition.cron: A string used to schedule work in more complex intervals. These are parsed with
It's possible to omit the
cron properties if you don't wish to schedule recurring work, and just want to register a job.
Runs a job as soon as possible, outside of the scheduled jobs. Demanded jobs still run with the same locking mechanism that scheduled jobs run with, ensuring only one instance runs the job at a time. This does not prevent any scheduled jobs from running, unless the demand is running at the same time as a scheduled job and all instances fail to acquire a lock on the job.
QA is used to registers functions that will invoked any time a job is run. This function can be called multiple times to register multiple QA functions.
qaFunction function will be called with
jobDefinition from the
hire function, as well as a
next function, which should be called when the QA function is complete.
next function returns a promise that can be used to get
For example, here is what a time logging QA function might look like.
Cancels any scheduled jobs with name
jobName. This does not stop any demanded jobs from running.
Shuts down a bossman instance, closing all redis connections. This does not cancel any scheduled work, and does not stop it from running in any other bossman instances.
How it works
Constructing a new bossman instance sets up an expired key listener on your redis database.
hire for a new job, Bossman sets a key in Redis that expire when the first run should occur.
When the key expires, the expired key listener is called and Bossman does the following:
- Attempt to get a lock to perform the work. Only one instance of bossman will acquire the lock.
- If the lock is acquired, then perform the work and move on.
- If the lock is not acquired, then move on.
- Schedule the next run of the job by setting a key that expires when the next run should occur.
It's worth noting that every instance of Bossman attempts to schedule the next run of the job. This is okay because Redis will only schedule the first one that it receives, thanks to the
NX option in
demand performs the same operation as
hire, except with a special key for demands.