Scheduling Tasks

Cleaning up Comments

Comments marked as spam or rejected by the admin are kept in the database as the admin might want to inspect them for a little while. But they should probably be removed after some time. Keeping them around for a week after their creation is probably enough.

Create some utility methods in the comment repository to find rejected comments, count them, and delete them:

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--- i/src/Repository/CommentRepository.php
+++ w/src/Repository/CommentRepository.php
@@ -5,7 +5,9 @@ namespace App\Repository;
 use App\Entity\Comment;
 use App\Entity\Conference;
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Persistence\ManagerRegistry;
+use Doctrine\ORM\QueryBuilder;
 use Doctrine\ORM\Tools\Pagination\Paginator;

 /**
@@ -13,6 +15,8 @@ use Doctrine\ORM\Tools\Pagination\Paginator;
  */
 class CommentRepository extends ServiceEntityRepository
 {
+    private const DAYS_BEFORE_REJECTED_REMOVAL = 7;
+
     public const COMMENTS_PER_PAGE = 2;

     public function __construct(ManagerRegistry $registry)
@@ -20,6 +24,27 @@ class CommentRepository extends ServiceEntityRepository
         parent::__construct($registry, Comment::class);
     }

+    public function countOldRejected(): int
+    {
+        return $this->getOldRejectedQueryBuilder()->select('COUNT(c.id)')->getQuery()->getSingleScalarResult();
+    }
+
+    public function deleteOldRejected(): int
+    {
+        return $this->getOldRejectedQueryBuilder()->delete()->getQuery()->execute();
+    }
+
+    private function getOldRejectedQueryBuilder(): QueryBuilder
+    {
+        return $this->createQueryBuilder('c')
+            ->andWhere('c.state = :state_rejected or c.state = :state_spam')
+            ->andWhere('c.createdAt < :date')
+            ->setParameter('state_rejected', 'rejected')
+            ->setParameter('state_spam', 'spam')
+            ->setParameter('date', new \DateTimeImmutable(-self::DAYS_BEFORE_REJECTED_REMOVAL.' days'))
+        ;
+    }
+
     public function getCommentPaginator(Conference $conference, int $offset): Paginator
     {
         $query = $this->createQueryBuilder('c')

Using Class Constants, Container Parameters, and Environment Variables

7 days? We could have chosen another number, maybe 10 or 20. This number might evolve over time. We have decided to store it as a constant on the class, but we might have stored it as a parameter in the container, or we might have even defined it as an environment variable.

Here are some rules of thumb to decide which abstraction to use:

• If the value is sensitive (passwords, API tokens, ...), use the Symfony secret storage or a Vault;
• If the value is dynamic and you should be able to change it without re-deploying, use an environment variable;
• If the value can be different between environments, use a container parameter;
• For everything else, store the value in code, like in a class constant.

Creating a CLI Command

Removing the old comments is the perfect task for a cron job. It should be done on a regular basis, and a little delay does not have any major impact.

Create a CLI command named app:comment:cleanup by creating a src/Command/CommentCleanupCommand.php file:

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namespace App\Command;

use App\Repository\CommentRepository;
use Symfony\Component\Console\Attribute\AsCommand;
use Symfony\Component\Console\Attribute\Option;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Style\SymfonyStyle;

#[AsCommand('app:comment:cleanup', 'Deletes rejected and spam comments from the database')]
class CommentCleanupCommand
{
    public function __invoke(
        SymfonyStyle $io,
        CommentRepository $commentRepository,
        #[Option(description: 'Dry run')]
        bool $dryRun = false,
    ): int {
        if ($dryRun) {
            $io->note('Dry mode enabled');

            $count = $commentRepository->countOldRejected();
        } else {
            $count = $commentRepository->deleteOldRejected();
        }

        $io->success(sprintf('Deleted "%d" old rejected/spam comments.', $count));

        return Command::SUCCESS;
    }
}

All application commands are registered alongside Symfony built-in ones and they are all accessible via symfony console. As the number of available commands can be large, you should namespace them. By convention, the application commands should be stored under the app namespace. Add any number of sub-namespaces by separating them by a colon (:).

A command declares its arguments and options with the #[Argument] and #[Option] attributes on the parameters of __invoke() (the $dryRun parameter becomes the --dry-run option). Symfony injects the other parameters based on their type: SymfonyStyle to write nicely-formatted output to the console, and any service, like the comment repository, the same way it does for controller arguments.

Clean up the database by running the command:

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$ symfony console app:comment:cleanup

Scheduling the Command

Running the command by hand works, but it should run every night. The Symfony Scheduler component generates messages on a schedule; they are then consumed by a worker, like any other Messenger messages.

Add the Scheduler component, along with the library that parses cron expressions:

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$ symfony composer req scheduler dragonmantank/cron-expression

Schedule the command with the #[AsCronTask] attribute:

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--- i/src/Command/CommentCleanupCommand.php
+++ w/src/Command/CommentCleanupCommand.php
@@ -7,8 +7,10 @@ use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Attribute\Option;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Style\SymfonyStyle;
+use Symfony\Component\Scheduler\Attribute\AsCronTask;

 #[AsCommand('app:comment:cleanup', 'Deletes rejected and spam comments from the database')]
+#[AsCronTask('50 23 * * *')]
 class CommentCleanupCommand
 {
     public function __invoke(

The attribute registers the command on the default schedule with a cron expression: every night at 11.50 pm (UTC). Check it:

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$ symfony console debug:scheduler

A schedule is exposed as a regular Messenger transport named after it; consume it like any other transport:

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$ symfony run -d symfony console messenger:consume scheduler_default -vv

Deploying the Schedule

On Upsun, the worker only consumes the async transport. Make it consume the schedule as well:

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--- i/.upsun/config.yaml
+++ w/.upsun/config.yaml
@@ -87,4 +87,4 @@ applications:
         messenger:
             commands:
                 # Consume "async" messages (as configured in the routing section of config/packages/messenger.yaml)
-                    start: symfony console --time-limit=3600 --memory-limit=64M messenger:consume async
+                    start: symfony console --time-limit=3600 --memory-limit=64M messenger:consume async scheduler_default

That's all it takes: no crontab, no extra process; the schedule lives in the PHP code, next to the task it triggers, and it is deployed and versioned like the rest of the application.

What about System Crons?

Upsun also supports OS-level cron jobs, described in .upsun/config.yaml alongside the web container and the workers; the default configuration already defines one that cleans up expired PHP sessions. System crons are a good fit for tasks that are not implemented in PHP.

The croncape utility used by the default cron monitors the execution of the command and sends an email to the addresses defined in the MAILTO environment variable if the command returns any exit code different than 0:

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$ symfony cloud:variable:create --sensitive=1 --level=project -y --name=env:MAILTO --value=ops@example.com

Note that crons are set up on all Upsun branches. If you don't want to run some on non-production environments, check the $PLATFORM_ENVIRONMENT_TYPE environment variable:

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if [ "$PLATFORM_ENVIRONMENT_TYPE" = "production" ]; then
    croncape symfony app:invoices:send
fi