gitlab-org--gitlab-foss/doc/development/sidekiq_style_guide.md

# Sidekiq Style Guide

This document outlines various guidelines that should be followed when adding or
modifying Sidekiq workers.

## Default Queue

Use of the "default" queue is not allowed. Every worker should use a queue that
matches the worker's purpose the closest. For example, workers that are to be
executed periodically should use the "cronjob" queue.

A list of all available queues can be found in `config/sidekiq_queues.yml`.

## Dedicated Queues

Most workers should use their own queue. To ease this process a worker can
include the `DedicatedSidekiqQueue` concern as follows:

```ruby
class ProcessSomethingWorker
  include Sidekiq::Worker
  include DedicatedSidekiqQueue
end
```

This will set the queue name based on the class' name, minus the `Worker`
suffix. In the above example this would lead to the queue being
`process_something`.

In some cases multiple workers do use the same queue. For example, the various
workers for updating CI pipelines all use the `pipeline` queue. Adding workers
to existing queues should be done with care, as adding more workers can lead to
slow jobs blocking work (even for different jobs) on the shared queue.

## Tests

Each Sidekiq worker must be tested using RSpec, just like any other class. These
tests should be placed in `spec/workers`.

## Removing or renaming queues

Try to avoid renaming or removing queues in minor and patch releases. 
During online update instance can have pending jobs and removing the queue can 
lead to those jobs being stuck forever. If you can't write migration for those 
Sidekiq jobs, please consider doing rename or remove queue in major release only.