Architecture

Pullup is composed by two components, a webhook and a controller. The diagram below describes how Pullup works. The left half of the diagram is managed by the webhook, and the right half is managed by the controller.

Webhook

Webhook receives incoming events from HTTP or GitHub, and executes matched Trigger resources. When a Trigger is triggered, it will create, update or delete ResourceTemplate resources, which will be consumed by Pullup controller later.

Controller

Controller maintains resource states according to ResourceTemplate resources.

When a new ResourceTemplate is created, the controller will create new resources according to templates, or copy existing resources and mutate copied resources with Strategic Merge Patch or JSON Patch.

After resources are created, the controller will track updates of ResourceTemplate. When a ResourceTemplate is updated, the resources created by it will also be updated automatically.

Finally, when a ResourceTemplate is deleted, the resources created by it will be deleted by Garbage Collection.