Pods vs Nodes vs Clusters: The Many Moving Parts of Kubernetes

Have you ever looked into the kitchen of a busy restaurant? Chances are you’ll see different chefs moving at different speeds all to achieve one goal- to make the best meal possible. From sous chefs to pastry chefs to even fry chefs, individuals with different roles work together under the eye of an executive chef to create some of the best dishes you’ve ever tasted. 

If Kubernetes is one of your favorite restaurants, then pods, nodes, and clusters are just some of the chefs operating behind the scenes. With Kubernetes being notoriously complex, these concepts start becoming muddled and confused with one another, though in the grand scheme, pods, nodes, and clusters all work together to push for stronger Kubernetes operations.

Here’s everything you need to know about pods vs nodes vs clusters.

What is a Container in Kubernetes?

Before finding the nuances in Kubernetes and its moving parts, it’s important to understand the basis of Kubernetes.

Kubernetes is an open source platform used to manage and orchestrate containerized services, with containers being tech that packages applications and their dependencies into a lightweight file. 

Containers are the preferred application vehicle for a variety of reasons. Containers are extremely flexible and able to run in any environment, are able to isolate themselves, and can even represent separate parts of an application rather than the whole. 

In the kitchen, the container is the executive chef, with the actions of the pods, nodes, and clusters being as a result of container operations.

What is a Kubernetes Pod?

If the container is the executive chef, then the pod is the sous chef working directly under the top boss.

Pods are a group of one or more containers, sharing resources and operation instructions amongst themselves while acting as the main power switch for containers. This shared aspect of pods is integral to facilitating successful container communication while retaining a degree of isolation. 

Outside of container operations, pods are extremely important in Kubernetes because of their ability to scale and replicate automatically in response to traffic and workload demands. It’s important to note that pods are ephemeral, meaning that once they complete their objective or once the node that hosts them fails, they become replaced and destroyed. To safeguard the container data housed within pods as well as a pod’s unique IP address, Kubernetes offers services designated for pod and node assistance.

That being said, pods are often run within clusters in two common ways:

• Single Container Operations: the most common Kubernetes use case, sees one container designated to a single pod, with Kubernetes managing that pod rather than directly managing containers
• Multi Container Operations: this approach sees pods representing the entire application composed of multiple containers that share resources

Pods are an integral means of container management and communication, offering automated scheduling that makes running them seamless. However, where do pods get their power from?

What is a Node in Kubernetes?

Nodes in Kubernetes represent another chef in the kitchen, providing their assistance in adding flavor to the dish.

A Kubernetes node is a virtual or physical machine depending on the cluster that provides power to run workloads. Typically, there would be several nodes running within a cluster, representing a variety of pods and containers.

Inside nodes is another kitchen, consisting of worker nodes and master (control plane) nodes. Worker nodes are responsible for actually running containers, enabling cluster scaling in the same process. Kubernetes control plane nodes, or master nodes, work within the realm of cluster management, offering capabilities in scheduling, anomaly detection, and more. Typically a single control plane node is needed in a cluster, though engineers default to more than one for fault tolerance. 

Nodes themselves are comprised of three main components:

• Kubelets: Agent that runs inside each nodes to ensure competent pod operations and communications, especially between master and worker nodes
• Container Runtime: Software that actually runs and manages containers, ensuring that the application run
• Kube proxy: Network proxy responsible for facilitating networking between nodes and entire clusters

Nodes are the battery to container operations, supplying power to pods that execute container tasks while ensuring that clusters are maintained. Users direct nodes through kubectl (Kubernetes’ native command-line interface), allowing actions such as getting nodes, scheduling and unscheduling them, and even draining nodes.

What is a Kubernetes Cluster?

If the container, pods, and nodes are chefs, then the cluster is the main dish!

A Kubernetes cluster consists of nodes that run containerized applications and services, with clusters enabling container operation across different machines and environments. As mentioned above, clusters are made up of one control plane node (one required, more than one recommended) and worker nodes, with these nodes containing pods that manage containers.

Clusters go deeper than just nodes and pods, consisting of the aforementioned kubelets and kube-proxy, but also components such as:

• API server: interface that serves as frontend for the Kubernetes control plane
• Scheduler: responsible for scheduling containers based on resource requirements while assigning pods to nodes
• Controller Manager: component responsible for running controller processes while managing other controllers
• Etcd: cluster data storage 

Much like an ordered dish in the kitchen, clusters have a desired state as specified by users. Components and scaling ensure that clusters will always be in the desired state, or will work towards achieving it.

Kubernetes Pod vs Node vs Cluster: The Grand Scheme

In a well-oiled kitchen, chefs aren’t going against each other, but rather working together to achieve a common goal. Much like a successful kitchen, it isn’t a case of Kubernetes pod vs node vs cluster, but rather how they work with each other to offer containerized apps and services the best deployment possible.

In the grand scheme of Kubernetes, containers are the priority. Grouping containers are pods, offering the resources and means of communication containers need to run smoothly, while also being isolated if necessary. Pods are placed into and run on nodes, with nodes themselves playing instrumental roles in running containers and cluster management. And encompassing the entire operation is a cluster, with clusters pushing container operation and injecting machine and environment flexibility. 

Kubernetes Operations with Lyrid

Kubernetes cluster vs node vs pod is a heavily confused topic within the Kubernetes communities, especially for those learning the tech. 

While it may seem like each component has different roles within the container orchestration service (and they do) it’s important to note that they don’t work against each other, but rather work with each other in the grand scheme of Kubernetes. 

Despite the distinction between pods, nodes, and clusters that we have made above, it’s undeniable that Kubernetes is painfully complex. From container operations to autoscaling and healing and more, Kubernetes has a ton of moving parts that are a pain to keep track of, even for the most seasoned developer. But it doesn’t have to be.

Lyrid Managed Kubernetes offers all the Kubernetes capabilities, without the headache of Kubernetes.  Our managed Kubernetes options offers features like:

• Cluster autoscaling
• Automated resource distribution
• Simple cluster management and cost optimization
• Lyrid Marketplace integrations
• End-to-end visibility

And more- all within one convenient platform! With Lyrid Managed Kubernetes, you no longer have to Google “Kubernetes nodes vs pods” or “Kubernetes pods integrations”, but instead have a Kubernetes environment that’s ready to deploy whenever you are!

Looking to learn more? Check out Lyrid Managed Kubernetes, and book a meeting with our product specialists for a free demo!