A computer cluster is the logical grouping of the machines and components that operate an orchestration system. It coordinates manager and worker machines around tasks, allowing applications to run across one machine or many. section 1.5.6 section 1.10
A cluster brings together the core orchestration components:
- A manager maintains cluster-wide state and coordinates the system. section 1.9.3
- Workers run the tasks assigned to them. section 1.5 section 1.9.3
- A scheduler places tasks on workers using the available cluster resources. section 1.5 section 1.5.7
From one machine to many
A cluster can run on a single physical or virtual machine, but production deployments commonly span multiple machines. Running several instances of a web API across workers allows the orchestration system to recover from an instance or machine failure without making the entire application unavailable. section 1.5.6 section 1.9.3
Figure 1.4 The basic components of an orchestration system. Regardless of what terms different orchestrators use, each has a scheduler, a manager, and a worker, and they all operate on tasks.
Use the component diagram to see how tasks connect the scheduler, manager, and workers within a cluster. section 1.5
