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
- đ Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.
- đ It originated from Google's internal system, Borg, and was open-sourced in 2014, which is why it's called Kubernetes.
- đ€ The abbreviation 'k8s' comes from the 8 letters between the 'k' and 's' in Kubernetes, similar to 'i18n' for internationalization.
- đ A Kubernetes cluster consists of nodes that run containerized applications, with a control plane managing the cluster's state.
- đ ïž The control plane includes core components like the API server, etcd, scheduler, and controller manager, each with specific responsibilities.
- đŠ Pods are the smallest deployable units in Kubernetes, hosting one or more containers and providing shared storage and networking.
- đ The scheduler in Kubernetes is responsible for efficiently placing pods onto worker nodes based on resource requirements.
- đ The controller manager runs controllers that maintain the desired state of the cluster, including replication and deployment controllers.
- đ§ Worker nodes contain components like kubelet, container runtime, and kube-proxy, which manage pod execution and network traffic.
- âïž Kubernetes offers scalability, high availability, self-healing, and portability, making it adaptable to various infrastructures.
- đĄ The complexity and cost of setting up and managing Kubernetes can be mitigated by using managed Kubernetes services provided by cloud providers.
- â For smaller organizations, the principle of YAGNI (You ainât 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
đ€ 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.
đ 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
đĄKubernetes
đĄk8s
đĄContainer Orchestration
đĄControl Plane
đĄWorker Nodes
đĄPods
đĄAPI Server
đĄetcd
đĄScheduler
đĄKubelet
đĄKube-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 ainât 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?
Letâs take a look.
Kubernetes is an open-source container orchestration platform.
It automates the deployment, scaling, and management of containerized applications.
Kubernetes can be traced back to Google's internal container orchestration system, Â
Borg, which managed the deployment of 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 way of abbreviating long words.
The number 8 in k8s refers to the 8 letters between the first letter âkâ Â
and the last letter âsâ in the word Kubernetes.
Other examples are i18n for internationalization, and l10n for localization.
A Kubernetes cluster is a set of machines, Â
called nodes, that are used to run containerized applications.
There are two core pieces in a Kubernetes cluster.
The first is the control plane.
It is responsible for managing the state of the cluster.
In production environments, the control plane usually Â
runs on multiple nodes that span across several data center zones.
The second is a set of worker nodes.
These nodes run the containerized application workloads.
The containerized applications run in a Pod.
Pods are the smallest deployable units in Kubernetes.
A pod hosts one or more containers Â
and provides shared storage and networking for those containers.
Pods are created and managed by the Kubernetes control plane.
They are the basic building blocks of Kubernetes applications.
Now letâs dive a bit deeper into the control plane.
It consists of a number of core components.
They are the API server, etcd, scheduler, and the controller manager.
The API server is the primary interface between the control plane and the rest of the cluster.
It exposes a RESTful API that allows clients to interact with the control Â
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 and other components of the control Â
plane to store and retrieve information about the cluster.
The scheduler is responsible for scheduling pods onto the worker nodes in the cluster.
It uses information about the resources required by the pods and the available Â
resources on the worker nodes to make placement decisions.
The controller manager is responsible for running controllers that manage the state of the cluster.
Some examples include the replication controller, Â
which ensures that the desired number of replicas of a pod are running, Â
and the deployment controller, which manages the rolling update and rollback of deployments.
Next, letâs dive deeper into the worker nodes.
The core components of Kubernetes that run on the worker nodes include kubelet, Â
container runtime, and kube proxy.
The kubelet is a daemon that runs on each worker node.
It is responsible for communicating with the control plane.
It receives instructions from the control plane about which pods to run on the node, Â
and ensures that the desired state of the pods is maintained.
The container runtime runs the containers on the worker nodes.
It is responsible for pulling the container images from a registry, Â
starting and stopping the containers, and managing the containers' resources.
The kube-proxy is a network proxy that runs on each worker node.
It is responsible for routing traffic to the correct pods.
It also provides load balancing for the pods and ensures that Â
traffic is distributed evenly across the pods.
So when should we use Kubernetes?
As with many things in software engineering, this is all about tradeoffs.
Letâs look at the upsides first.
Kubernetes is scalable and highly available.
It provides features like self-healing, automatic rollbacks, and horizontal scaling.
It makes it easy to scale our applications up and down as needed, Â
allowing us to respond to changes in demand quickly.
Kubernetes is portable.
It helps us deploy and manage applications in a consistent Â
and reliable way regardless of the underlying infrastructure.
It runs on-premise, in a public cloud, or in a hybrid environment.
It provides a uniform way to package, 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 for organizations new to container orchestration.
It requires a high level of expertise and resources to set Â
up and manage a production Kubernetes environment.
The second drawback is cost.
Kubernetes requires a certain minimum level of Â
resources to run in order to support all the features we mentioned above.
It is likely an overkill for many smaller organizations.
One popular option that strikes a reasonable balance is to offload Â
the management of the control plane to a managed Kubernetes service.
Managed Kubernetes services are provided by cloud providers.
Some popular ones are Amazon EKS, GKEÂ on Google Cloud, and AKS on Azure.
These services allow organizations to run the Kubernetes applications Â
without having to worry about the underlying infrastructure.
They take care of tasks that require deep expertise, like setting up and configuring Â
the control plane, scaling the cluster, and providing ongoing maintenance and support.
This is a reasonable option for a mid-size organization to test out Kubernetes.
For a small organization, YAGNI - You ainât gonna need it - is our recommendation.
If you would like to learn more about system design, check out our books and weekly newsletter.
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