1.2.1.3 Worker Nodes

Worker nodes within the Kubernetes cluster are used to run containerized applications and handle networking to ensure that traffic between applications across the cluster and from outside of the cluster can be properly facilitated. The worker nodes perform any actions triggered via the Kubernetes API, which runs on the master node.

All nodes within a Kubernetes cluster must run the following services:

  • The Kubelet Service: the agent that allows each worker node to communicate with the API Server running on the master node. This agent is also responsible for setting up pod requirements, such as mounting volumes, starting containers and reporting status.

  • A Container Runtime: an environment where containers can be run. In this release, only Docker is supported. Therefore, the runtime here is equivalent to the Docker Engine.

  • The Kube Proxy Service: a service that programs iptables rules to handle port forwarding and IP redirects to ensure that network traffic from outside the pod network can be transparently proxied to the pods in a service.

In all cases, these services are run from systemd as inter-dependent daemons.