[Scheduler] How to compose a Schedule from multiple places? #58431

melkamar · 2024-10-01T19:24:12Z

melkamar
Oct 1, 2024

How can I compose a single Schedule from different places in code through some kind of extension points?

My use case is that:

I want there to be a limited amount of Schedules, because each Schedule needs its own bin/console messenger:consume scheduler_NAME worker running. I want to keep the infrastructure simple without running many different workers.
I want to add recurring messages from any place in the codebase

The "convenience" attributes #[AsPeriodicTask] and #[AsCronTask] do what I am looking for - they add new triggers to the schedule. However, I couldn't find a way to be able to add new triggers through "rich" PHP code where more customization can be made. See code below.

This defines the foo schedule with a single trigger:

#[AsSchedule('foo')]
class FooSchedule implements ScheduleProviderInterface
{
    private Schedule $schedule;

    public function getSchedule() : Schedule
    {
        return $this->schedule ??= (new Schedule())
            ->with(
                RecurringMessage::every(
                    '10 seconds',
                    new FooMessage('Hello'),
                )
            );
    }
}

Now, in a different service, I would like to add another trigger to the existing schedule. I tried two approaches:

Through another #[AsSchedule] attribute.

#[AsSchedule('foo')]
class ExtendingSchedule implements ScheduleProviderInterface
{
    private Schedule $schedule;

    public function getSchedule() : Schedule
    {
        return $this->schedule ??= (new Schedule())
            ->with(
                RecurringMessage::every(
                    '20 seconds',
                    new FooMessage('Extended hello'),
                )
            );
    }
}

This does not work (as could be expected) and only one of the duplicate foo schedules will be registered - the other is completely ignored.

Through dependency injection of the FooSchedule in a service. This one I thought should work, but I get container build errors.

class SomeService
{
    public function __construct(
        FooSchedule             $fooSchedule,
    )
    {
        $fooSchedule->getSchedule()->add(
            RecurringMessage::every('20 seconds', new FooMessage('Extended hello'))
        );
    }
}

This results in:

Cannot autowire service "SomeService": argument "$fooSchedule" of method "__construct()" references class "FooSchedule" but no such service exists.

Looking at the FooSchedule class, which is registered as a service, I see that it is overwritten in the container and assigned a different class!

$ bin/console debug:container FooSchedule

 // This service is a private alias for the service scheduler.provider.default

Information for Service "scheduler.provider.default"
====================================================

 ----------------- ------------------------------------------------------------------------------------------------------
  Option            Value
 ----------------- ------------------------------------------------------------------------------------------------------
  Service ID        scheduler.provider.default
  Class             Symfony\Component\Scheduler\Schedule
  Tags              scheduler.schedule_provider (name: default)
                    container.decorator (id: FooSchedule, inner: scheduler.provider.default.inner)
  Calls             add
  Public            no
  Synthetic         no
  Lazy              no
  Shared            yes
  Abstract          no
  Autowired         no
  Autoconfigured    no
  Factory Service   scheduler.provider.default.inner
  Factory Method    getSchedule
  Usages            FooSchedule
                    SomeService
                    .service_locator.GQvl1cG
 ----------------- ------------------------------------------------------------------------------------------------------

My FooSchedule is hidden behind a decorator (I think) and the DI fails.

So, given that these do not work, what is the recommended and supported way of composing schedules? I have scoured the documentation and all the examples I have come across only show a simplistic case where the schedule is defined in one class.

I am thinking that I could collect all the "extending services" myself through custom tags and autowiring in the Schedule class, but it feels there should be a more out-of-the-box way to do that.

Thank you

norkunas · 2024-10-02T03:54:16Z

norkunas
Oct 2, 2024

I want there to be a limited amount of Schedules, because each Schedule needs its own bin/console messenger:consume scheduler_NAME worker running. I want to keep the infrastructure simple without running many different workers.

But you can just write messenger:consume SCHEDULER_1_NAME SCHEDULER_2_NAME ... and have a single worker

1 reply

melkamar Oct 2, 2024
Author

Thanks for the answer, though there are some more issues with this that I should have expanded on in the question. We have a containerized deployment, one of the containers is currently the "scheduler" and runs cron as its entrypoint.

If we changed it to run messenger:consume, then the entrypoint would need to be adjusted every time someone adds a new schedule somewhere in the codebase. I think this would be easy to forget about. I tried messenger:consume scheduler_* to solve this, but the argument does not support a wildcard like this.
In addition, our project is deployed in various "configurations" with different bundles loaded, but the same deployment model. This means that the configuration of which schedules to consume will need to be dynamic per deployment. I looked at programmatically creating the Scheduler consumers, but the documentation states: If you are using it in the framework context, it is highly recommended to use the messenger:consume command as explained in the previous section. From that I assumed there is a better way.
I suppose an approach could be to have an entrypoint script which first collects all the schedule names and then build a list of args for the messenger:consume command. The only available command at the moment is debug:scheduler though, which is not intended to be read from a script. (I can implement my own of course, but this not being already available tells me this is not the supported way to work with this)

I think what I am missing from the documentation (this is not throwing blame) is what the best practice is. Is it expected that each logical "feature" has its own schedule with even just one or two tasks and the workers consume many different transports? Or is it recommended to have fewer large schedules (e.g. one with a lock and stateful for large tasks, one for quick tasks)?

rpander93 · 2025-07-16T18:16:34Z

rpander93
Jul 16, 2025

I ran into this myself today and decided to create a command that implements approach (2) from @melkamar's list: https://gist.github.com/rpander93/609ac5e429827577cacf79ddb7f58e22

1 reply

AlexeyKosov Nov 28, 2025

Here's a bit simpler implementation: https://gist.github.com/AlexeyKosov/c45d7354e8488d7498c641b96ac13f14

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[Scheduler] How to compose a Schedule from multiple places? #58431

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melkamar Oct 1, 2024

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