One article tells you what kubernetes is

Ask me what is Kubernetes ？ You might as well go from Kubernetes The name speaks of .

Start with the name

Kubernetes The word comes from Greek , signify “ helmsman ”、“ The pilot ”. from Kubernetes Blue rudder logo Look at , What it takes is “ helmsman ” One mind .

Kubernetes Blue logo

The reason for taking “ helmsman ” One mind , It is because it borrows a figurative metaphor of the container ——“ Container ”. We vividly compare containers to shipping containers . The container enables each application to be installed and deployed in different environments without difference , For example, containers enable different goods to be transported uniformly in different ports .Kubernetes Borrowed “ Container ” This metaphor , Meaning hope to be the helmsman on the ship , Deliver containers safely and smoothly to all terminals , Transport management of numerous containers , That is to manage a large number of containers .

Steering the management container Kubernetes

The above is right Kubernetes An image understanding of , Let's take a look at Kubernetes Formal definition of .

Formal definition

Kubernetes The official website gives the definition ：

Kubernetes It's a portable 、 Scalable open source platform , For managing containerized workloads and services , Promotes declarative configuration and Automation . Kubernetes With a huge and rapidly growing ecosystem .Kubernetes Service for 、 Support and tools are widely available .

Kubernetes Is an open source container choreography tool , Originally developed by Google . Its basic function is to manage containers , The container can be Docker Containers , It can also be containers from other technologies . This further means Kubernetes Can help manage applications made up of hundreds or thousands of containers .Kubernetes You can manage these containers in different environments , Such as physical machine environment , Virtual machine environment , Or cloud environment , Even mixed environments .

Simply speaking ,Kubernetes Is a tool for container orchestration , So what is the concept of container choreography ？ Let's first understand the background of container choreography , This is just like Kubernetes The reason why such container choreography tools come into being .

The background of container choreography

Due to the increasing complexity of applications , And all sorts of other reasons , Microservice architecture is emerging . The rise of microservices has also greatly increased the use of containers , This is because the microservice framework splits and decouples a large single application to form many small independent microservice applications , The container is the best way to load and deploy these small micro services .

The rise of microservices has promoted the development of containers

The rise of microservices and containers further makes some applications composed of hundreds or even thousands of containers , At this time, the management of many containers has become a huge challenge . Managing these containers across multiple environments using scripts and homegrown tools is very complex , Sometimes it is even impossible for some scenes , This eventually led to the need for container choreography techniques .

Management challenges for large-scale containers

So how does container choreography manage these numerous containers ？ This is the same question Kubernetes What kind of function does it have ？ Here are a few simple concrete examples to illustrate .

How container choreography manages containers

Intelligent deployment

• Specify the deployment area

When we deploy applications , You can tell Kubernetes Our deployment requirements , Specify the deployment area we want . For example, in the following example , We want to deploy the application to the region A ,Kubernetes Observe the size specification of the container to be deployed , For example, what the container needs CPU 、 Memory size, etc , Then according to our needs in the region A Looking for a host that meets our needs , And create an instance of the container . Besides Kubernetes Very intelligent , It will be in the area A Select relatively idle 、 Hosts with relatively low resource utilization . In our case , host B Compared with the host A More free , therefore Kubernetes Priority will be given to the host B Create our container application instance on .

Deployed in the region A Relatively idle hosts in B

• Specify deployment resources

We can also ask Kubernetes Specify the specific resources required by the application , For example, deploy a machine learning application , The application needs to run on the GPU Training the model on the machine . We can approach Kubernetes Specify this deployment requirement , next Kubernetes According to our needs, we will look for products with GPU The host , Deployment of applications .

Deployed in GPU Region B

• Specify the deployment copy

Kubernetes It can help us easily deploy copies of multiple application instances . For example, tell Kubernetes We need two copies of the app ,Kubernetes An application instance will be deployed on two different hosts by default , To prevent single point failure , Improve application availability . After the application runs , Tell me again Kubernetes We need three copies of the application ,Kubernetes Will find the right host , Create another copy .

Create multiple copies

Load balancing

Kubernetes It will automatically detect the load of the container , If the container load is found to be too high , such as CPU Utilization is too high 、 Or the response time is too long ,Kubernetes A copy of the container is automatically created , Deploy and expand capacity . Take the following example , host D The upper container load is too high ,Kubernetes Automatically create a copy of the container , Distribute the load to multiple containers to achieve load balancing , Improve application response time .

Automatically create replicas for load balancing

Automatic recovery

Kubernetes It has the function of health check , If a container application unfortunately exits unexpectedly due to a failure ,Kubernetes This state will be detected , Then it will automatically migrate the containers that have failed , That is, restart a new container instance in a new place , Corresponding storage resources 、 The load balancing distribution rule will be associated to the new container instance , To complete an automatic recovery of the container .

The failed node automatically recovers

These are the basic contents of container arrangement , It's also Kubernetes Several basic functions of . Of course Kubernetes There are more powerful features , Such as error recovery 、 Log aggregation 、 Monitoring warning 、 Data persistence 、 Service discovery 、 Resource management 、 Configuration Management 、 The secret key management 、 Traffic forwarding, etc .

Kubernetes Some features and functions given on the official website

Except for the angle of container arrangement , We can also continue to understand from different angles Kubernetes.

From different perspectives Kubernetes

From all perspectives kubernetes

Operation and maintenance ：Kubernetes It is a resource docking platform . We can put the host of the data center , Storage and network resources are handed over to Kubernetes, Give Way Kubernetes Automatically allocate these resources to applications that need them , Reduce manual operation , Improve operation and maintenance efficiency .

Development perspective ：Kubernetes It is a distributed system management platform .Kubernetes It can help us deploy applications to hundreds of hosts , For application deployment 、 Operation and management support , Make the operation and deployment of distributed systems easier .

Project perspective ：Kubernetes It's an open source project , It does not belong to any commercial company , It is the cloud native Computing Foundation CNCF Its core open source projects .

Development perspective ：Kubernetes Like an operating system in the cloud age .Linux、Windows The operating system helps us manage the computing of a single host 、 Storage and network resources , and Kubernetes Managed the computing of hundreds of hosts for us 、 Storage and network resources , And through the arrangement and management of containers , Realize the effective utilization of resources .Kubernetes It's like a distributed operating system , The container instance running on it is equivalent to the process in the distributed operating system .

Kubernetes Not the only container orchestration management tool , stay 2014 year Docker The company took the lead in releasing the container layout tool Docker Swarm, Then there was a battle for container choreography .

The battle of container choreography

Containers The battle of choreography

In order to fight with Docker The container business ecosystem with the company as the core , stay Kubernetes After the release ,Google、Red Hat And other open source infrastructure companies CNCF The foundation , I hope to Kubernetes Based on , Build a vendor led open source infrastructure 、 A platform community operated by an independent foundation .

Final Kubernetes With the following advantages, we finally won the victory ：

• The accumulation is rich

Kubernetes Derived from Google The long-standing large-scale cluster management system Borg.Kubernetes Standing on the shoulders of giants , With the help of Borg The system has more than ten years of practical experience and technical precipitation , Will succeed Google All applications run over 100 10000 servers 、 exceed 80 Data centers , Weekly 20 Billion containers .

• Flexible design

Compared with simple function 、 Ecologically self closing Swarm project ,Kubernetes With its powerful functions, it is far behind . adopt Kubernetes, Users can choose according to their own usage scenarios 、 Through flexible plugging , Adopt custom network 、 Storage 、 Dispatch 、 monitor 、 Log and other modules .

• Open source

Kubernetes Enter the public's view as open source for the first time , user 、 Communities and major enterprises have embraced Kubernetes, Start supporting... On your own products Kubernetes. In user 、 With the support of the community and big factories , Kubernetes It has gradually become the deployment standard of enterprise infrastructure and a new generation of application service layer .

Docker The company in Kubernetes After the rise and expansion of the community , Finally, I was defeated ,Kubernetes It has become the mainstream container choreography tool , Then, there are many problems based on Kubernetes Business Edition services and products .

Kubernetes Open source projects and commercial products

Kubernetes It's an open source project , It is the core open source project under the cloud native Computing Foundation , Therefore, it does not belong to any software manufacturer , Anyone and organization can get it for free Kubernetes Source code and binary files , However, the open source community does not provide product support for business users , In order to meet the needs of enterprise users , Many vendors are based on open source Kubernetes Open source projects for , Provides a commercial version of Kubernetes Services and products , For example, in the private cloud, there are Red Hat OpenShift, Major cloud manufacturers also provide Kubernetes Service for , Such as Azure Upper AKS 、GCP Upper GKE etc.

Open source projects to commercial software

Kubernetes It's the cloud age “ operating system ”, It provides an important foundation for the implementation of hybrid cloud and multi cloud architectures , It is playing an important role in the development of cloud primordial .