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Version: 0.17.0

Recurring Jobs

In most web apps, users send requests to the server and receive responses with some data. When the server responds quickly, the app feels responsive and smooth.

What if the server needs extra time to fully process the request? This might mean sending an email or making a slow HTTP request to an external API. In that case, it's a good idea to respond to the user as soon as possible and do the remaining work in the background.

Wasp supports background jobs that can help you with this:

  • Jobs persist between server restarts,
  • Jobs can be retried if they fail,
  • Jobs can be delayed until a future time,
  • Jobs can have a recurring schedule.

Using Jobs​

Job Definition and Usage​

Let's write an example Job that will print a message to the console and return a list of tasks from the database.

  1. Start by creating a Job declaration in your .wasp file:
main.wasp
job mySpecialJob {
  executor: PgBoss,
  perform: {
    fn: import { foo } from "@src/workers/bar"
  },
  entities: [Task],
}
  1. After declaring the Job, implement its worker function:
src/workers/bar.js
export const foo = async ({ name }, context) => {
  console.log(`Hello ${name}!`)
  const tasks = await context.entities.Task.findMany({})
  return { tasks }
}
The worker function

The worker function must be an async function. The function's return value represents the Job's result.

The worker function accepts two arguments:

  • args: The data passed into the job when it's submitted.
  • context: { entities }: The context object containing entities you put in the Job declaration.
  1. After successfully defining the job, you can submit work to be done in your Operations or setupFn (or any other NodeJS code):
someAction.js
import { mySpecialJob } from 'wasp/server/jobs'

const submittedJob = await mySpecialJob.submit({ job: "Johnny" })

// Or, if you'd prefer it to execute in the future, just add a .delay().
// It takes a number of seconds, Date, or ISO date string.
await mySpecialJob
  .delay(10)
  .submit({ name: "Johnny" })

And that's it. Your job will be executed by PgBoss as if you called foo({ name: "Johnny" }).

In our example, foo takes an argument, but passing arguments to jobs is not a requirement. It depends on how you've implemented your worker function.

Recurring Jobs​

If you have work that needs to be done on some recurring basis, you can add a schedule to your job declaration:

main.wasp
job mySpecialJob {
  executor: PgBoss,
  perform: {
    fn: import { foo } from "@src/workers/bar"
  },
  schedule: {
    cron: "0 * * * *",
    args: {=json { "job": "args" } json=} // optional
  }
}

In this example, you don't need to invoke anything in . You can imagine foo({ job: "args" }) getting automatically scheduled and invoked for you every hour.

Job executors​

Wasp supports Jobs through the use of job executors. A job executor is responsible for handling the scheduling, monitoring, and execution of jobs.

Currently, Wasp only has support for one job executor, PgBoss.

PgBoss​

PgBoss is a lightweight job queue built on top of PostgreSQL. It is suitable for low-volume production use cases and does not require any additional infrastructure or complex management. By using PostgreSQL (and SKIP LOCKED) as its storage and synchronization mechanism, you get many benefits of a traditional job queue, on top of your existing Postgres database.

Requirements​

PgBoss requires that your database provider is set to "postgresql" in your schema.prisma file. Read more about setting the provider here.

Limitations​

PgBoss runs together with your web server, whenever it is up. This means that it is not a separate process or service, but rather a part of your web server's application. As such, it is not suitable for CPU-heavy workloads, as it shares the CPU with your web server's application logic.

The PgBoss executor in Wasp does not (yet) support independent, horizontal scaling of pg-boss-only applications, nor starting them as separate workers/processes/threads. This means that your server must be running whenever you want to process jobs. If you need to scale your job processing, you will need to run multiple instances of your web server, each with its own PgBoss instance.

Customization​

If you need to customize the creation of the PgBoss instance, you can set an environment variable called PG_BOSS_NEW_OPTIONS to a stringified JSON object containing the initialization parameters. See the pg-boss documentation.

Please note that setting PG_BOSS_NEW_OPTIONS environment variable overwrites all Wasp defaults, so you must include the connectionString parameter inside it as well.

For example, to set the connection string and change the job archival and deletion settings, you can set the environment variable like this:

# In an .env file
PG_BOSS_NEW_OPTIONS={"connectionString":"postgresql://user:password@server:5432/database","archiveCompletedAfterSeconds":86400,"deleteAfterDays":30,"maintenanceIntervalMinutes":5}

# In the shell
PG_BOSS_NEW_OPTIONS='{"connectionString":"postgresql://user:password@server:5432/database","archiveCompletedAfterSeconds":86400,"deleteAfterDays":30,"maintenanceIntervalMinutes":5}'

You can read more about escaping JSON in environment variables in the JSON Env Vars documentation.

Database setup​

You don't need to set up the database manually

When using PgBoss, the database setup is automatically taken care of by the Wasp server, and doesn't need to be reflected in your schemas or migrations. The following information is given for your reference, and is explained in more detail in the PgBoss documentation.

All job data will be stored in a separate database schema called pgboss. It has some internal tracking tables, such as job, archive, and schedule. PgBoss tables have a name column in most tables that will correspond to your Job identifier. Additionally, these tables maintain arguments, states, return values, retry information, start and expiration times, and other metadata required by PgBoss.

Known issues​

  • Renaming scheduled jobs

    The job name/identifier in your .wasp file is the same name that will be used in the name column of pgboss tables. If you change a name that had a schedule associated with it, pg-boss will continue scheduling those jobs but they will have no handlers associated, and will thus become stale and expire. To resolve this, you can remove the applicable row from the pgboss.schedule table.

    For example, if you renamed a job from emailReminder to sendEmailReminder, you would need to remove the old scheduled job with the following SQL query:

    BEGIN;
    DELETE FROM pgboss.schedule WHERE name = 'emailReminder';
    COMMIT;

    Important: Only modify the database directly if you're comfortable with SQL operations. If you're unsure, consider keeping the old job name or restarting with a fresh database in development.

Job data retention and cleanup​

By default, PgBoss keeps job data for 12 hours after completion or failure. After that, it moves the data to an archive table, where it is kept for 7 days before being deleted. If you want to change this behavior, you can configure the PG_BOSS_NEW_OPTIONS environment variable to set custom values for job archival (archivedCompletedAfterSeconds/archiveFailedAfterSeconds) and removal (deleteAfterSeconds/deleteAfterMinutes/etc).

PG_BOSS_NEW_OPTIONS={"connectionString":"...your postgress connection url...","archiveCompletedAfterSeconds":86400,"deleteAfterDays":30,"maintenanceIntervalMinutes":5}

API Reference​

Declaring Jobs​

main.wasp
job mySpecialJob {
  executor: PgBoss,
  perform: {
    fn: import { foo } from "@src/workers/bar",
    executorOptions: {
      pgBoss: {=json { "retryLimit": 1 } json=}
    }
  },
  schedule: {
    cron: "*/5 * * * *",
    args: {=json { "foo": "bar" } json=},
    executorOptions: {
      pgBoss: {=json { "retryLimit": 0 } json=}
    }
  },
  entities: [Task],
}

The Job declaration has the following fields:

  • executor: JobExecutor required

    The job executor to use for this job. Currently, the only supported executor is PgBoss.

  • perform: dict required

    • fn: ExtImport required

      • An async function that performs the work. Since Wasp executes Jobs on the server, the import path must lead to a NodeJS file.
      • It receives the following arguments:
        • args: Input: The data passed to the job when it's submitted.
        • context: { entities: Entities }: The context object containing any declared entities.

      Here's an example of a perform.fn function:

      src/workers/bar.js
      export const foo = async ({ name }, context) => {
        console.log(`Hello ${name}!`)
        const tasks = await context.entities.Task.findMany({})
        return { tasks }
      }

    • executorOptions: dict

      Executor-specific default options to use when submitting jobs. These are passed directly through and you should consult the documentation for the job executor. These can be overridden during invocation with submit() or in a schedule.

      • pgBoss: JSON

        See the docs for pg-boss.

  • schedule: dict

    • cron: string required

      A 5-placeholder format cron expression string. See rationale for minute-level precision here.

      If you need help building cron expressions, Check out Crontab guru.

    • args: JSON

      The arguments to pass to the perform.fn function when invoked.

    • executorOptions: dict

      Executor-specific options to use when submitting jobs. These are passed directly through and you should consult the documentation for the job executor. The perform.executorOptions are the default options, and schedule.executorOptions can override/extend those.

      • pgBoss: JSON

        See the docs for pg-boss.

  • entities: [Entity]

    A list of entities you wish to use inside your Job (similar to Queries and Actions).

JavaScript API​

  • Importing a Job:

    someAction.js
    import { mySpecialJob } from 'wasp/server/jobs'

  • submit(jobArgs, executorOptions)

    • jobArgs: Input
    • executorOptions: object

    Submits a Job to be executed by an executor, optionally passing in a JSON job argument your job handler function receives, and executor-specific submit options.

someAction.js
const submittedJob = await mySpecialJob.submit({ job: "args" })

  • delay(startAfter)

    • startAfter: int | string | Date required

    Delaying the invocation of the job handler. The delay can be one of:

    • Integer: number of seconds to delay. [Default 0]
    • String: ISO date string to run at.
    • Date: Date to run at.
someAction.js
const submittedJob = await mySpecialJob
  .delay(10)
  .submit({ job: "args" }, { "retryLimit": 2 })

Tracking​

The return value of submit() is an instance of SubmittedJob, which has the following fields:

  • jobId: The ID for the job in that executor.
  • jobName: The name of the job you used in your .wasp file.
  • executorName: The Symbol of the name of the job executor.

There are also some namespaced, job executor-specific objects.

  • For pg-boss, you may access: pgBoss
    • details(): pg-boss specific job detail information. Reference
    • cancel(): attempts to cancel a job. Reference
    • resume(): attempts to resume a canceled job. Reference