aws

How can I use PgDice in production?

This collection of files is how I use PgDice in production. I'll describe the architecture here so you'll have a place to start.

1. tasks/poll_sqs.rake is run using some sort of process manager like systemd on the ec2 instance. I like to run the poll_sqs stuff on my Sidekiq instances because they are the ones who eventually handle the work anyway.

2. lib/sqs_poller.rb is used to handle the looping logic for the rake task. It invokes lib/sqs_listener.rb for each iteration.

3. lib/sqs_listener.rb calls AWS SQS to receive messages and then passes each one into the lib/sqs_listener/sqs_event_router.rb to be routed to the correct message handler.

4. Inside lib/sqs_listener/sqs_event_router.rb the message is parsed and passed through a case statement. This could be abstracted better but for now if the message has a field of event_type and a value of "task" then the router will send it off to the TaskEventHandler which in this case is lib/sqs_listener/typed_event_handler/task_event_handler.rb

5. In the TaskEventHandler the task is sent to a handler which responds to the task specified in the message body field task.

6. The handler for the task (in this case, DatabaseTasks) handles the parameters for invoking the Sidekiq worker: PgDiceWorker

7. Finally, the PgDiceWorker is called and handles invoking PgDice based on the parameters passed in.

Hopefully that wasn't too confusing. There's a lot of steps in here because the system that uses PgDice handles lots of different types of SQS events and needs to be as resilient as possible.