Updated at: 2022-04-02 GMT+08:00

Basic Concepts

For details about the basic concepts of Kubernetes clusters, see Basic Concepts of CCE.

Cluster

A cluster is a group of one or more cloud servers (also known as nodes) in the same subnet. A cluster can be seen as one or more elastic cloud servers (also called nodes) in a same subnet. It provides computing resource pool for the container running through computer groups formed by relevant technologies.

Pod

A pod is the smallest and simplest unit in the Kubernetes object model that you create or deploy. A pod encapsulates an application container (or, in some cases, multiple containers), storage resources, a unique network IP address, and options that govern how the container(s) should run.

Workload

A workload is an abstract model of a group of pods in Kubernetes. Workloads defined in Kubernetes include Deployments, StatefulSets, jobs, and DaemonSets.

  • Deployment: Pods of a deployment are completely independent of each other and deliver the same functions. Deployments support auto scaling and rolling updates. Typical examples include Nginx and WordPress.
  • StatefulSet: Pods in a StatefulSet are not completely independent of each other. StatefulSets have stable persistent storage and stable unique network identifiers. They support ordered, graceful deployment, scaling, and deletion. Typical examples include MySQL-HA and etcd.
  • Job: It is a one-time task that runs to completion. It can be executed immediately after being created.
  • Cron job: It runs a job periodically on a given schedule. For example, you can create a cron job that will perform time synchronization for all active nodes at a fixed time point.
Figure 1 Relationship between workloads and pods

Federated Workload

A federated workload describes a workload deployed across clusters. You can use federated workloads to deploy workloads to Kubernetes clusters you selected. Currently, only federated Deployments are supported.

Federated Service

Different workload access types are provided to address diverse scenarios. In multi-cloud scenarios, a federated service is added for mutual access between workloads in different clusters in the federation. You can manage these services on MCP in a centralized manner.

Federated Ingress

Enhanced ELB is used for an ingress. Compared with layer-4 ELB, layer-7 ELB newly supports Uniform Resource Identifiers (URI) configurations and distributes access traffic to the corresponding service based on the corresponding URIs. A federated ingress refers to the ingress component used in multi-cloud scenarios. The federated ingresses can be managed on MCP in a unified manner.

Federated PVC

A PersistentVolumeClaim (PVC) refers to cluster file storage. However, a federated PVC is oriented to the federation layer. File storage is created for multiple clusters at the same time, and differentiated settings can be configured for each cluster. A federated PVC manages file storage in clusters in a unified manner.

Component

A component is the minimum unit in MCP. It provides an independent function module or microservice and supports unified O&M in multi-cloud scenarios.

ContainerOps

ContainerOps enables continuous integration (CI) and continuous delivery (CD) of containerized applications throughout the entire process from source code to deployment, providing capabilities such as image repository, image build, version management, and release pipelines.

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