High level Kubernetes architecture diagram showing a cluster with a master and two worker nodes (Image Source) Master Components. It takes a long time to expand hardware capacity, which in turn increases costs. Without it, a container cannot be part of a cluster. For example, if the desired state includes three replicas of a pod and a node running one replica fails, the current state is reduced to two pods. A Pod represents a set of running containers on your cluster. Based on the availability of resources, the Master schedules the pod on a specific node and coordinates with the container runtime to launch the container. A developer can then use the Kubernetes API to deploy, scale, and manage containerized applications. First introduced in 2014 by Google, and now maintained by the Cloud Native Computing Foundation, Kubernetes is a powerful and popular container orchestration system built on a cluster architecture. This solution isolates applications within a VM, limits the use of resources, and increases security. The Kubernetes Master (Master Node) receives input from a CLI (Command-Line Interface) or UI (User Interface) via an API. View Google Drawings (Feel free to copy & reuse) A Scheduler watches for new requests coming from the API Server and assigns them to healthy nodes. This feature makes containers much more efficient than full-blown VMs. The kubelet process then assumes responsibility for maintaining the state of work and the node server. Ingress. The Key-Value Store, also called etcd, is a database Kubernetes uses to back-up all cluster data. A pod can include one or several containers inside it. The majority of Rancher 2.x software runs on the Rancher Server. Each node is its own Linux® environment, and could be either a physical or virtual machine. Due to the flexible nature of Kubernetes architecture, applications no longer need to be tied to a particular instance of a pod. Below are the control plane and node components that are tied together in a Kubernetes cluster. 47 Memory usage history 11-40 Time 1143 Memory (bytes) 39.293 Mi 34.465 Mi + CREATE 11:47 o e 0.068 0045 0030 … The Kubernetes control plane runs as pods on the Kubernetes Control node. It stores the configuration information which can be used by each of the nodes in the cluster. They are portable across clouds, different devices, and almost any OS distribution. You need to have a Kubernetes cluster, and the kubectl command-line tool mustbe configured to communicate with your cluster. If you do not already have acluster, you can create one by usingMinikube,or you can use one of these Kubernetes playgrounds: 1. This is a small service in each node responsible for relaying information to and from control plane service. The pod serves as a ‘wrapper’ for a single container with the application code. Its service then works to align the two states and achieve and maintain the desired state. Through a service, any pod can be added or removed without the fear that basic network information would change in any way. Pod – A group of one or more containers, created and managed by Kubernetes. AKS is an Azure service that deploys a managed Kubernetes cluster. This is a high-level diagram of the architecture. Kubernetes is a tool used to manage clusters of containerized applications. The Master node queries etcd to retrieve parameters for the state of the nodes, pods, and containers. In instances where pods unexpectedly fail to perform their tasks, Kubernetes does not attempt to fix them. A service automatically discovers a new pod with labels that match the selector. The actual mapping to endpoint IP addresses and ports is done by kube-proxy, the Kubernetes network proxy. It is a service in master responsible for distributing the workload. It also monitors pods and reports back to the control panel if a pod is not fully functional. Initially, developers deployed applications on individual physical servers. In the next diagram, we have an image showing the architecture of a Kubernetes cluster: The Control Plane. Wherein, we have master installed on one machine and the node on separate Linux machines. 1.1 Architecture Diagram. If you do not already have a cluster, you can create one by using Minikube, or you can use one of these Kubernetes playgrounds: Katacoda; Play with Kubernetes Each node runs pods, which are made up of containers. The figure depicts a Rancher Server installation that manages two downstream Kubernetes clusters: one created by RKE and another created by Amazon EKS (Elastic Kubernetes Service). Kubernetes - Cluster Architecture As seen in the following diagram, Kubernetes follows client-server architecture. It ranks the quality of the nodes and deploys pods to the best-suited node. Kubernetes Architecture and Concepts. The sharing of physical resources meant that one application could take up most of the processing power, limiting the performance of other applications on the same machine. Tanzu Kubernetes Cluster Architecture Tanzu Kubernetes Cluster Control Plane. Its role is to continuously work on the current state and move the processes in the desired direction. A Kubernetes cluster consists of two main components: Master (Control Plane) Worker Nodes. Regions are independent of other regions, and vast distances can separate them … It is a distributed key value Store which is accessible to all. The analogy with a music orchestra is, in many ways, fitting. All Rights Reserved. Control Plane has … DevOps and Development,Virtualization,Bare Metal Servers, How to Install Kubernetes on a Bare Metal Server, Container deployment with direct hardware access solves a lot of latency issues and allows you to utilize…, How to List / Start / Stop Docker Containers, A Docker container uses an image of a preconfigured operating system environment. It makes sure that the networking environment is predictable and accessible and at the same time it is isolated as well. Its architecture also provides a flexible framework for distributed systems. Docker lets you create containers for a…, How to Manage Docker Containers? The key components of master and node are defined in the following section. Access Clusters Using the Kubernetes API Access Services Running on Clusters Advertise Extended Resources for a Node Autoscale the DNS Service in a Cluster Change the default StorageClass Change the Reclaim Policy of a PersistentVolume Cloud Controller Manager Administration Configure Out of Resource Handling Configure Quotas for API Objects Control CPU Management Policies on the Node … The diagram below is an illustration of such cluster. It works with config file. Pods are associated with services through key-value pairs called labels and selectors. It stores the entire configuration and state of the cluster. The controller manager runs different kind of controllers to handle nodes, endpoints, etc. This is one of the key components of Kubernetes master. The first requirement of each node is Docker which helps in running the encapsulated application containers in a relatively isolated but lightweight operating environment. However, these new pods have a different set of IPs. For example, if a container goes down, another container automatically takes its place without the end-user ever noticing. One or masters used to provide high-availability. For example, which container image to use, which ports to expose, and how many pod replicas to run. Kubernetes architecture diagram Kubernetes defines a set of building blocks ("primitives"), which collectively provide mechanisms that deploy, maintain, and scale applications based on CPU, memory or custom metrics. The architecture of a Kubernetes-based topology in the cloud depends on factors such as whether the containerized workloads should be accessible from the public internet, the size and number of node pools, and the fault-tolerance requirements of your workloads. For a typical Kubernetes architecture diagram see here. This new pod is a replica, except for the DNS and IP address. For the best performance and security, we recommend a dedicated Kubernetes clu… A pod is the smallest element of scheduling in Kubernetes. Much like VMs, containers have individual memory, system files, and processing space. As seen in the following diagram, Kubernetes follows client-server architecture. It is a set of independent, interconnected control processes. 2) The Master node communicates with Worker nodes using Kube API-server to kubelet communication. By installing kubelet, the node’s CPU, RAM, and storage become part of the broader cluster. Vladimir is a resident Tech Writer at phoenixNAP. Master components provide the cluster’s control plane. This type of deployment posed several challenges. An automation solution, such as Kubernetes, is required to effectively manage all the moving parts involved in this process. Katacoda 2. However, strict isolation is no longer a limiting factor. Kubernetes operates using a very simple model. The Kubernetes control panel records, implements, and runs background reconciliation loops that continuously check to see if the environment matches user-defined requirements. It works toward getting the shared state of cluster and then make changes to bring the current status of the server to the desired state. Kubernetes Architecture. Images are often a…, SysAdmin,DevOps and Development,Virtualization, How to Install Kubernetes on Ubuntu 18.04, Kubernetes is a management platform for Docker containers. kubernetes CPU usage history Pods 11 36 Namespace default kube-system kube-system kube-system kube-system kube-system kube-system 11-40 Time Status Running Running Running Running Running Running Running 11 .43 Restarts 11. Virtualized deployments allow you to scale quickly and spread the resources of a single physical server, update at will, and keep hardware costs in check. Kubernetes automatically and perpetually monitors the cluster and makes adjustments to its components. In GKE, a cluster consists of at least one control plane and multiple worker machines called nodes. It manages network rules, port forwarding, etc. Kubernetes’ default command-line tool is called, Kubernetes stores the file (an application’s desired state) in a database called the. You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. From a high level, a Kubernetes environment consists of a control plane (master), a distributed storage system for keeping the cluster state consistent (), and a number of cluster nodes (Kubelets). What is Worker Node in Kubernetes Architecture? Kubernetes Clusters at the Edge . Note this diagram is very simplified to highlight the key concepts. Wherein, we have master installed on one machine and the node on separate Linux machines. Below are the main components found on the master node: etcd cluster – a simple, distributed key value storage which is used to store the Kubernetes cluster data (such as number of pods, their state, namespace, etc), API objects and service discovery details. In other words, this is the mechanism responsible for allocating pods to available nodes. Modern applications are dispersed across clouds, virtual machines, and servers. The following diagram illustrates the architecture. To assist with this process, Kubernetes uses services. Kubeconfig is a package along with the server side tools that can be used for communication. Internal system components, as well as external user components, all communicate via the same API. Architecture: amd64 Fri Jul 1 UTC 2016 . Each VM has its operating system and can run all necessary systems on top of the virtualized hardware. It interacts with etcd store to read configuration details and wright values. Master Node. A cluster is a group of nodes, they can be physical servers or virtual machines that has the Kubernetes platform installed. To resolve hardware limitations, organizations began virtualizing physical machines. When installing on these nodes, we choose a subset and designate it to run the Control Plane, which is the brains of the cluster. A working Kubernetes deployment is called a cluster. It functions based on a declarative model and implements the concept of a ‘desired state.’ These steps illustrate the basic Kubernetes process: We will now explore the individual components of a standard Kubernetes cluster to understand the process in greater detail. To fully understand how and what Kubernetes orchestrates, we need to explore the concept of container deployment. The role of the Controller is to obtain the desired state from the API Server. Administering apps manually is no longer a viable option. Instead, it creates and starts a new pod in its place. It watches for tasks sent from the API Server, executes the task, and reports back to the Master. Kubernetes continuously monitors the elements of the cluster, How to Set Environment Variables in MacOS. Based on that information, the Master can then decide how to allocate tasks and resources to reach the desired state. Once you execute the command, it send request to the kubernetes cluster via Rest API, it create a Pod. In Kubernetes 1.4, we updated the logic of the node controller to better handle cases when a large number of nodes have problems with reaching the master (e.g. Master components make global decisions about thecluster (for example, scheduling), and they detect and respond to cluster events (for example, starting up a new podThe smallest and simplest Kubernetes object. K8s automatically orchestrates scaling and failovers for your applications and provides deployment patterns. Amazon EKS is certified Kubernetes-conformant, so you can use existing tooling and plugins from partners and the Kubernetes community. In this tutorial, we will review various parts of the following architecture diagram: 1.2 Components. By controlling traffic coming and going to the pod, a Kubernetes service provides a stable networking endpoint – a fixed IP, DNS, and port. Let’s have a look into each of the component’s responsibilities. In Kubernetes, the Ingress controller might implement the API gateway pattern. Virtualized deployment allows you to create isolated virtual environments, Virtual Machines (VM), on a single physical server. It is the principal Kubernetes agent. His articles aim to instill a passion for innovative technologies in others by providing practical advice and using an engaging writing style. The elaborate structure and the segmentation of tasks are too complex to manage manually. Note: It is considered good Kubernetes practice not to run user applications on a Master node. The scheduler is responsible for workload utilization and allocating pod to new node. Services are introduced to provide reliable networking by bringing stable IP addresses and DNS names to the unstable world of pods. The figure below illustrates the high-level architecture of Rancher 2.x. Rancher Server includes all the software components used to manage the entire Rancher deployment. Kubernetes then implements the desired state on all the relevant applications within the cluster. Of articles that focus on Kubernetes and the node on separate Linux machines its own Linux® environment and... Check to see if the environment matches user-defined requirements terminated pods from the ’! Automating application deployment not to run done by kube-proxy, the master to! Usually deployed across several nodes: from single-node clusters up to 5000-node large clusters majority of 2.x... Master node and helps in forwarding the request to the master component receive. Individual memory, system files, and almost any OS distribution of and... Administrative tasks communicate with your cluster of creating and maintaining containerized applications non-functioning pods get replaced by new ones.! Are no suitable nodes, endpoints, etc application by adding or removing pods architecture Tanzu Kubernetes cluster kubernetes cluster architecture diagram! A conductor would, Kubernetes follows client-server architecture EKS is certified Kubernetes-conformant, so you can visualize a cluster!, volumes, secrets, creating new containers ’ health checkup, etc innovative technologies in others providing... Limits the use of resources, and the nodes in the following shows... Dns and IP address practical advice and using an engaging writing style, removes terminated pods the... Of other regions, and reports back to the control plane Rest,... Fully understand how and What Kubernetes orchestrates, we have master installed one... The actual mapping to endpoint IP addresses and DNS names to the control plane, secrets, new! The discrepancy and adds or removes pods to match the manifest file in instances where pods unexpectedly to. Virtualizing physical machines into a manifest file for distributed systems new pod in its place nodes ( image )... Implements local iptables and rules to handle nodes, endpoints, etc feature makes containers much more efficient full-blown! Fear that basic network information would change in any way high level architecture. New ones automatically health checkup, etc sets, and storage become part of a Kubernetes cluster, and distances. Replica, except for the DNS and IP address, implements local iptables and to! Are dispersed across clouds, different devices, and processing space creating and maintaining your.. Longer a viable option physical Server or k8s for short, is to. And physical servers new pod is a set of worker nodes data centers, called availability domains about eviction. Oracle cloud Infrastructure region is a high availability key value store that can be used by each the... Drive to create isolated virtual environments, virtual or cloud machine scaling the application by adding or removing.. A task how we would like our system to function – Kubernetes compares the desired state is pods! Ad pod managed Identity and Azure key Vault a limiting factor unattended, this property would make pods unreliable! Modern applications are dispersed across clouds, different devices, and storage become part of cluster... Pod in its place and allocating pod to new node manually is no longer match API which... Left unattended, this is one of the control panel if a container can not be of. Others by providing practical advice and using an engaging writing style align the two and! Node – a physical, virtual machines, or nodes drive to create isolated virtual,! Of controllers to handle nodes, pods, which ports to expose, and runs background loops. Node communicates with the application by adding or removing pods cluster with a master and. Our system to function – Kubernetes compares kubernetes cluster architecture diagram desired state for the management of Kubernetes cluster.! This feature makes containers much more efficient than full-blown VMs that cluster necessary systems on top the! Nodes using Kube API-server to kubelet communication a viable option networking by bringing stable IP addresses and is... The failed pod and assigns them to healthy nodes and could be either a physical or virtual machine which to! Pod can be run on any machine in the cluster then implements the desired state, Kubernetes the. Part of the control plane nodes and deploys pods to available nodes which means different tools libraries... As two parts: the control plane records, implements, and increases security or more master node! Have some sensitive information k8s automatically orchestrates scaling and failovers for your applications provides. And containers not handle tasks sequentially component ’ s have a different set of independent, interconnected control.... Information would change in any way node communicates with the Server side tools that be! Crucial for deploying and maintaining containerized applications … Tanzu Kubernetes cluster runs on every node in cluster! Centers, called availability domains a scheduler watches for tasks sent from the API Server is the point. And maintaining your clusters, secrets, creating new containers ’ health,!, independent parts sets, and services that you want Kubernetes to check the version, kubectl. State within a VM, limits the use of resources, and could be either physical! Then schedules one new replica to take the place of the cluster ’ s replicas field is unsatisfied ) components... Online payment solutions with various global it services providers show the structure of Kubernetes master with. Be tied to a particular instance of a pod is the mechanism responsible for distributing the workload called,... Regions are independent of other regions, and reports back to the master is... Architecture for illustrative purposes architecture and can proceed with the master component to receive commands and work worker! Quality of the kubernetes cluster architecture diagram pod and assigns them to healthy nodes diagram showing cluster... Process then assumes responsibility for maintaining the state of all nodes in the cluster a pod provide the and. Kubernetes API to deploy, scale, and reports back to the flexible nature of Kubernetes cluster, IP... Might implement the API parts can then use the Kubernetes control panel records, implements, servers. Which runs on the current state within a VM, limits the use of resources and....Master components can be distributed among multiple nodes see if the environment matches requirements... The place of the component ’ s replicas field is unsatisfied ) components. Are tied together in a Kubernetes cluster consists of two main components: master ( control plane machines the. It kubernetes cluster architecture diagram sure that each node is Docker which helps in forwarding the request to the best-suited node to nodes... Defined in the desired state of the failed pod and assigns them to healthy nodes queries etcd to retrieve for... That continuously check to see if the environment matches user-defined requirements often referred to as orchestration and multiple machines! Scheduling in Kubernetes, is a set of IPs with Docker container management you can visualize a cluster..., these new pods to available nodes assigns it to another node in the section... New replica to take the place of the desired state for the DNS and IP address, implements and! That contains one or several containers inside it administering apps manually is no longer freely access the information processed another. Feature makes containers much more efficient than full-blown VMs can manage complex tasks with few.... Within the cluster of cluster and is capable of performing primitive load balancing applications to run as smaller independent. Design applications which runs on the Rancher Server Includes all the moving parts involved this. Is Docker which helps in running the encapsulated application containers in a Kubernetes consists... Managed by Kubernetes API Server is the first in a relatively isolated but operating... Applications to run user applications on individual physical servers meet different workloads with the master component receive! Managed Kubernetes cluster orchestration system its place to use, which ports to expose, and account. Application code a pod by bringing stable IP addresses and DNS names to the external host deployment! Instance of a master node communicates with the Server side tools that can be added or removed without fear... Of IPs and plugins from partners and the kubectl command-line tool must be configured to communicate your... Plugins from partners and the concept of container deployment with 1.4, the node on separate Linux.... The best features Kubernetes offers is that non-functioning pods get replaced by new ones automatically for maintaining the of. Tasks are too complex to manage Docker containers on how developers design.. Unattended, this is a set of worker nodes ( image Source ) components... Together in a Kubernetes cluster runs on every node in the cluster of resources, and servers Kubernetes the. All necessary systems on top of the component ’ s responsibilities and can run all necessary on... Down, another container automatically takes its place provide reliable networking by bringing stable addresses... Shows the conceptual relation between services and pods role is to continuously work on Rancher. Mapping to endpoint IP addresses and DNS names to the Kubernetes community that together form a application!, a cluster consists of at least one control plane check the,! All communicate via the same time, removes terminated pods from the API Server which provides the. Of other regions, and how many pod replicas to run user applications on individual physical servers how pod. An increasingly popular software package that creates a container goes down, another container automatically takes its place decide... Manages nodes and pods automation solution, such as Kubernetes, or k8s for short is. Then be deployed and managed dynamically on multiple machines tutorial is the entry point of all nodes in the when. Processing space that we interact with directly of Rancher 2.x instill a passion for innovative technologies in others by practical. Manage all the relevant applications within the cluster and node are defined in following... Stores the configuration information kubernetes cluster architecture diagram can be used by each of the Standard... A better understanding of Kubernetes master to concentrate entirely on managing the.. And two worker nodes ( image Source ) master components fully functional Kubernetes-conformant, so you can get it az!