Concepts

In Swarm clusters, applications are similar to projects. One application consists of multiple services. A service is an instance that provides specific functions of an application. Services support horizontal scaling.

In Kubernetes clusters, applications are deployments that expose functions externally. A deployment manages one or more pods and containers. Pods are the smallest deployable computing units in Kubernetes. One pod may consist of multiple containers. A pod is meant to run a single instance of an application. Pods support horizontal scaling and can be scheduled to different nodes.

In Kubernetes clusters, service is an abstract concept. You can use services to expose deployments to external users.

When you create an application in a Swarm cluster, you can choose one of the following methods to expose the application. All these methods enable external access to the application.

• <HostIP>:<port>
• Simple routing
• SLB routing

After you create an application in a Kubernetes cluster, you need to create services to expose the application. To access an application from within a Kubernetes cluster, you can use service names, which only support internal access. To access an application from outside a Kubernetes cluster, you can create NodePort or LoadBalancer services to expose the application.

• ClusterIP (Supports internal access)
• NodePort (Similar to <HostIP>:<port> in Swarm clusters)
• LoadBalancer (Similar to SLB routing in Swarm clusters)
• Domain names based on ingresses. (Similar to simple routing in Swarm clusters)