Configure Workers

Workers are background processes that run alongside your main application. They are typically used for processing long-running tasks, handling queues, or performing scheduled jobs.

Basic Worker Configuration

You can define workers in your config.cap.yaml under the workers section. Each worker needs a unique name and either a command or subcommand to execute.

Note

Learn more about subcommands in the application types documentation.

workers:
  my-queue-processor:
    command: "php artisan queue:work --queue=my_queue"
    replicas: 1
    resources: # Optional resource allocation for this worker
      cpu: 250m
      memory: 512Mi

Property	Type	Description	Default
replicas	integer	The number of instances of this worker to run.	1
command	string or array	The full command to execute (e.g., php /app/script.php). See YAML Schema Reference.
subcommand	string or array	The command to run using the application's framework binary (e.g., queue:work). See YAML Schema Reference.
resources	object	Define CPU and memory resources for this worker. See YAML Schema Reference.	Defaults from application type

Custom Base Image Required for Subcommands

The subcommand option generates a command with a custom binary that is only available within our base container. Only use this feature if you are using our base container.

RabbitMQ Autoscaling for Workers

CAP optionally supports autoscaling for workers based on RabbitMQ queue length. This allows your workers to scale up automatically when there's a backlog of messages and scale down when the queue is empty, optimizing resource usage.

Simple Autoscaling

A simple configuration is to just set scale: true on the worker object. This will automatically configure scaling based on the worker's name as the queue and a default scaling vector (e.g., scale up when more than 20 messages are in the queue).

workers:
  runner:
    scale: true

Advanced Autoscaling Configuration

You can customize the scaling behavior by providing more details in the scale block:

workers:
  runner:
    replicas: 2 # Minimum number of workers
    scale:
      enable: true
      connection: "default" # Name of the RabbitMQ connection to use (defaults to 'default')
      queue: "my-custom-queue" # Name of the queue to monitor for scaling (defaults to the worker's name)
      vector: 5 # Determines when to scale workers based on queue length (base value 20)
      maxReplicas: 10 # Maximum number of replicas for the scaler (defaults to 10)

Properties for scale:

Property	Type	Description	Default
enable	boolean	Whether to enable autoscaling for this worker.	false
connection	string	The name of the RabbitMQ connection to use.	'default'
queue	string	The name of the RabbitMQ queue to monitor for scaling.	Worker's name
vector	integer	A multiplier for the queue length to determine the target number of replicas.	20
maxReplicas	integer	The maximum number of worker replicas that can be scaled up to.	10

Note

The replicas property in the main worker configuration still defines the minimum number of workers that will always be running, even when autoscaling is enabled and the queue is empty.