Orca is the orchestration engine for Spinnaker. It is responsible for taking a pipeline or task definition and managing the stages and tasks, coordinating the other Spinnaker services.
Orca pipelines are composed of stages which in turn are composed of tasks. The tasks of a stage share a common context and can publish to a global context shared across the entire pipeline allowing multiple stages to co-ordinate. For example a bake stage publishes details of the image it creates which is then used by a deploy stage.
Orca persists a running execution to Redis.