Kubernetes Explained in 6 Minutes | k8s Architecture
Summary
TLDRKubernetes, an open-source container orchestration platform, automates the deployment, scaling, and management of containerized applications. Originating from Google's Borg, it facilitates a scalable and highly available system with self-healing and automatic rollbacks. Despite its complexity and high resource requirements, Kubernetes offers portability across different infrastructures. Managed Kubernetes services like Amazon EKS, GKE, and AKS provide an accessible entry point for organizations, balancing the need for orchestration with the overhead of managing the system.
Takeaways
- š Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.
- š It originated from Google's internal system, Borg, and was open-sourced in 2014, which is why it's called Kubernetes.
- š¤ The abbreviation 'k8s' comes from the 8 letters between the 'k' and 's' in Kubernetes, similar to 'i18n' for internationalization.
- š A Kubernetes cluster consists of nodes that run containerized applications, with a control plane managing the cluster's state.
- š ļø The control plane includes core components like the API server, etcd, scheduler, and controller manager, each with specific responsibilities.
- š¦ Pods are the smallest deployable units in Kubernetes, hosting one or more containers and providing shared storage and networking.
- š The scheduler in Kubernetes is responsible for efficiently placing pods onto worker nodes based on resource requirements.
- š The controller manager runs controllers that maintain the desired state of the cluster, including replication and deployment controllers.
- š§ Worker nodes contain components like kubelet, container runtime, and kube-proxy, which manage pod execution and network traffic.
- āļø Kubernetes offers scalability, high availability, self-healing, and portability, making it adaptable to various infrastructures.
- š” The complexity and cost of setting up and managing Kubernetes can be mitigated by using managed Kubernetes services provided by cloud providers.
- ā For smaller organizations, the principle of YAGNI (You aināt gonna need it) may apply, suggesting that Kubernetes might be overkill for their needs.
Q & A
What is Kubernetes?
-Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.
Why is Kubernetes abbreviated as 'k8s'?
-The abbreviation 'k8s' comes from the 8 letters between the 'k' and the 's' in the word 'Kubernetes', following a common practice in tech to abbreviate long words.
What is the origin of Kubernetes?
-Kubernetes originated from Google's internal container orchestration system called Borg, which was open-sourced in 2014.
What are the two core components of a Kubernetes cluster?
-The two core components of a Kubernetes cluster are the control plane, responsible for managing the state of the cluster, and the worker nodes, which run the containerized application workloads.
What is the role of the control plane in a Kubernetes cluster?
-The control plane is responsible for managing the state of the cluster, including the API server, etcd, scheduler, and controller manager, which handle various aspects of cluster management.
What are Pods in Kubernetes?
-Pods are the smallest deployable units in Kubernetes, hosting one or more containers and providing shared storage and networking for those containers.
What is the function of the scheduler in the control plane?
-The scheduler is responsible for scheduling pods onto the worker nodes in the cluster, making placement decisions based on the resources required by the pods and the available resources on the worker nodes.
What are the main components that run on the worker nodes in Kubernetes?
-The main components running on the worker nodes include kubelet, container runtime, and kube-proxy, which handle communication with the control plane, container operations, and network routing, respectively.
Why is Kubernetes considered scalable and highly available?
-Kubernetes is scalable and highly available due to features like self-healing, automatic rollbacks, and horizontal scaling, allowing applications to scale up and down quickly in response to demand changes.
What are the downsides of using Kubernetes?
-The downsides of using Kubernetes include its complexity in setup and operation, which requires a high level of expertise and resources, and the cost associated with running the system to support its features.
What is a managed Kubernetes service and how does it benefit organizations?
-A managed Kubernetes service is provided by cloud providers like Amazon EKS, GKE on Google Cloud, and AKS on Azure. It allows organizations to run Kubernetes applications without managing the underlying infrastructure, handling tasks that require deep expertise.
Outlines
š¤ Introduction to Kubernetes
Kubernetes is an open-source platform for automating deployment, scaling, and management of containerized applications. Originating from Google's Borg, Kubernetes was open-sourced in 2014. The name 'k8s' is an abbreviation representing the 8 letters between 'k' and 's'. A Kubernetes cluster comprises nodes, with a control plane managing the cluster's state and worker nodes running the applications in Pods, which are the smallest deployable units. The control plane includes the API server, etcd, scheduler, and controller manager, each with specific responsibilities for cluster management and state maintenance. Worker nodes feature components like kubelet, container runtime, and kube-proxy to ensure smooth operation and traffic management.
š Advantages and Considerations of Using Kubernetes
Kubernetes offers scalability, high availability, self-healing, automatic rollbacks, and horizontal scaling, allowing for quick adaptation to demand changes. It also provides portability across different environments, ensuring consistent application deployment. However, the platform's complexity requires significant expertise and resources, making it potentially overwhelming for smaller organizations. The cost of running Kubernetes can be high, but managed Kubernetes services from cloud providers like Amazon EKS, Google's GKE, and Azure's AKS offer a balance by handling infrastructure and maintenance. For small organizations, the principle of YAGNI (You Ain't Gonna Need It) is recommended, suggesting that Kubernetes might be more than necessary. The script also encourages further learning about system design through books and newsletters.
Mindmap
Keywords
š”Kubernetes
š”k8s
š”Container Orchestration
š”Control Plane
š”Worker Nodes
š”Pods
š”API Server
š”etcd
š”Scheduler
š”Kubelet
š”Kube-proxy
Highlights
Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.
Kubernetes originated from Google's internal container orchestration system, Borg, which managed the deployment of thousands of applications within Google.
The name 'Kubernetes' is abbreviated as 'k8s', with the '8' representing the 8 letters between the 'k' and 's'.
A Kubernetes cluster consists of machines called nodes that run containerized applications.
The control plane in a Kubernetes cluster manages the state of the cluster and usually runs across multiple nodes and data center zones in production.
Worker nodes in a Kubernetes cluster run the containerized application workloads.
Pods are the smallest deployable units in Kubernetes, hosting one or more containers with shared storage and networking.
The control plane's core components include the API server, etcd, scheduler, and controller manager.
The API server serves as the primary interface between the control plane and the rest of the cluster, exposing a RESTful API for cluster management.
Etcd is a distributed key-value store used for storing the cluster's persistent state.
The scheduler in Kubernetes is responsible for making placement decisions for pods onto worker nodes based on resource requirements.
The controller manager runs controllers that manage the state of the cluster, including replication and deployment controllers.
Kubelet is a daemon on worker nodes that communicates with the control plane and manages the desired state of pods.
The container runtime on worker nodes is responsible for running containers, pulling images from a registry, and managing container resources.
Kube-proxy is a network proxy that routes traffic to the correct pods and provides load balancing.
Kubernetes offers scalability, high availability, self-healing, automatic rollbacks, and horizontal scaling for applications.
Kubernetes is portable and provides a consistent way to package, deploy, and manage applications across different environments.
The main drawbacks of Kubernetes include its complexity in setup and operation, as well as the high upfront cost for organizations new to container orchestration.
Managed Kubernetes services provided by cloud providers like Amazon EKS, GKE, and AKS can help organizations run Kubernetes applications without managing the underlying infrastructure.
For small organizations, the YAGNI principle (You aināt gonna need it) may apply when considering the adoption of Kubernetes.
Transcripts
What is Kubernetes?
Why is it called k8s?
What makes it so popular?
Letās take a look.
Kubernetes is an open-sourceĀ container orchestration platform.
It automates the deployment, scaling, andĀ management of containerized applications.
Kubernetes can be traced back to Google'sĀ internal container orchestration system,Ā Ā
Borg, which managed the deployment ofĀ thousands of applications within Google.
In 2014, Google open-sourced a version of Borg.
That is Kubernetes.
Why is it called k8s?
This is a somewhat nerdy wayĀ of abbreviating long words.
The number 8 in k8s refers to the 8Ā letters between the first letter ākāĀ Ā
and the last letter āsā in the word Kubernetes.
Other examples are i18n forĀ internationalization, and l10n for localization.
A Kubernetes cluster is a set of machines,Ā Ā
called nodes, that are used toĀ run containerized applications.
There are two core pieces in a Kubernetes cluster.
The first is the control plane.
It is responsible for managingĀ the state of the cluster.
In production environments,Ā the control plane usuallyĀ Ā
runs on multiple nodes that spanĀ across several data center zones.
The second is a set of worker nodes.
These nodes run the containerizedĀ application workloads.
The containerized applications run in a Pod.
Pods are the smallestĀ deployable units in Kubernetes.
A pod hosts one or more containersĀ Ā
and provides shared storage andĀ networking for those containers.
Pods are created and managed byĀ the Kubernetes control plane.
They are the basic buildingĀ blocks of Kubernetes applications.
Now letās dive a bit deeperĀ into the control plane.
It consists of a number of core components.
They are the API server, etcd,Ā scheduler, and the controller manager.
The API server is the primary interface betweenĀ the control plane and the rest of the cluster.
It exposes a RESTful API that allowsĀ clients to interact with the controlĀ Ā
plane and submit requests to manage the cluster.
etcd is a distributed key-value store.
It stores the cluster's persistent state.
It is used by the API server andĀ other components of the controlĀ Ā
plane to store and retrieveĀ information about the cluster.
The scheduler is responsible for schedulingĀ pods onto the worker nodes in the cluster.
It uses information about the resourcesĀ required by the pods and the availableĀ Ā
resources on the worker nodesĀ to make placement decisions.
The controller manager is responsible for runningĀ controllers that manage the state of the cluster.
Some examples include the replication controller,Ā Ā
which ensures that the desired numberĀ of replicas of a pod are running,Ā Ā
and the deployment controller, which managesĀ the rolling update and rollback of deployments.
Next, letās dive deeper into the worker nodes.
The core components of Kubernetes thatĀ run on the worker nodes include kubelet,Ā Ā
container runtime, and kube proxy.
The kubelet is a daemon thatĀ runs on each worker node.
It is responsible for communicatingĀ with the control plane.
It receives instructions from the controlĀ plane about which pods to run on the node,Ā Ā
and ensures that the desiredĀ state of the pods is maintained.
The container runtime runs theĀ containers on the worker nodes.
It is responsible for pulling theĀ container images from a registry,Ā Ā
starting and stopping the containers,Ā and managing the containers' resources.
The kube-proxy is a network proxyĀ that runs on each worker node.
It is responsible for routingĀ traffic to the correct pods.
It also provides load balancingĀ for the pods and ensures thatĀ Ā
traffic is distributed evenly across the pods.
So when should we use Kubernetes?
As with many things in softwareĀ engineering, this is all about tradeoffs.
Letās look at the upsides first.
Kubernetes is scalable and highly available.
It provides features like self-healing,Ā automatic rollbacks, and horizontal scaling.
It makes it easy to scale ourĀ applications up and down as needed,Ā Ā
allowing us to respond toĀ changes in demand quickly.
Kubernetes is portable.
It helps us deploy and manageĀ applications in a consistentĀ Ā
and reliable way regardless ofĀ the underlying infrastructure.
It runs on-premise, in a publicĀ cloud, or in a hybrid environment.
It provides a uniform way to package,Ā deploy, and manage applications.
Now how about the downsides?
The number one drawback is complexity.
Kubernetes is complex to set up and operate.
The upfront cost is high, especially forĀ organizations new to container orchestration.
It requires a high level ofĀ expertise and resources to setĀ Ā
up and manage a production Kubernetes environment.
The second drawback is cost.
Kubernetes requires a certain minimum level ofĀ Ā
resources to run in order to supportĀ all the features we mentioned above.
It is likely an overkill forĀ many smaller organizations.
One popular option that strikes aĀ reasonable balance is to offloadĀ Ā
the management of the control planeĀ to a managed Kubernetes service.
Managed Kubernetes services areĀ provided by cloud providers.
Some popular ones are Amazon EKS, GKEĀ on Google Cloud, and AKS on Azure.
These services allow organizationsĀ to run the Kubernetes applicationsĀ Ā
without having to worry aboutĀ the underlying infrastructure.
They take care of tasks that require deepĀ expertise, like setting up and configuringĀ Ā
the control plane, scaling the cluster, andĀ providing ongoing maintenance and support.
This is a reasonable option for a mid-sizeĀ organization to test out Kubernetes.
For a small organization, YAGNI - You ainātĀ gonna need it - is our recommendation.
If you would like to learn more about systemĀ design, check out our books and weekly newsletter.
Please subscribe if you learn something new.
Thank you and we'll see you next time.
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