Kubernetes (1): introduction to kubernetes

Preface

      Since last month , Because of the need of work and interest , Bloggers start learning Kubernetes, Up to now, it can be said that it is just a beginning . Learning alone is better than learning together , Later, the blogger will learn and present the learning content in the form of a blog post , I hope to discuss with you some questions , In constant communication, there are complementary , Learn together to improve . This series is named 【 Pride Kubernetes】, That's what it takes , Try to learn it well . Talk less , Now I'm proud of it Kubernetes The journey .

The goal is ：

1、Kubernetes What is it ？ Why Kubernetes？

2、Kubernetes and Docker Relationship of

3、Kubernetes Architecture of

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1、Kubernetes What is it ？ Why Kubernetes？

    In recent years, all of you have experienced the popularity of micro service , Whether it's a job interview , Or public number friends circle advertising training courses , It's about microservices . As more and more monomer projects become microservices , And the micro service splitting of the college case , There needs to be an application that can automatically schedule a large number of microservices 、 To configure 、 Supervision and troubleshooting , And this is Kubernetes The positioning of .

    Take a look at the official website Kubernetes The definition of ：Kubernetes is an open source container orchestration engine for automating deployment, scaling, and management of containerized applications.

    You can see it , It's an open source container choreography engine , This engine can be deployed automatically 、 Scaling and managing containerized applications . On the whole, it's not much different from what we summarized above .

    That's it Kubernetes What is it , What are its advantages ？ Why use it ？

1)、 Simplify application deployment ： That is, you don't need to pay attention to which machine your application is deployed on ,Kubernetes It will automatically prepare the computing and storage resources you need . And as long as clusters are built in the same way , It can also ensure the consistency of the development test production environment .

2)、 Better use of hardware ：Kubernetes When assigning an execution node to an application , Will automatically match the best nodes , Improve resource utilization .

3)、 Health check-up and self-healing ：Kubernetes It will monitor the status of the node where your application is executing , When it fails , It will reschedule other nodes to fill in , There's no need for human participation .

4)、 Automatic expansion ： Can make Kubernetes Automatically respond to the load of the application , For example, increase or decrease nodes .

 2、Kubernetes and Docker Relationship of

    Before we talk about their relationship , First of all, I want to mention Docker What is it .

    Docker It's a package 、 Container platform for distributing and running applications . The container is equivalent to a lightweight virtual machine . Virtual machine is a new operating system based on host computer , The programs in the virtual machine are executed on this virtual operating system . The container, as a program, is still executed on the host's operating system , So compared with the virtual machine container, there is no need to create an additional set of operating system , Saving resources , More lightweight . Container isolation mechanism , By means of Linux Name space and cgroup To achieve .

      Let's see Docker and Kubernetes Relationship of . From the first part above Kubernetes We know in the definition of ,Kubernetes It's a container choreography engine , Can manage containerized applications . This is what containerization means Docker, namely Kubernetes management Docker Containers that come out of containers . Of course, with the development of containerization Technology , except Docker outside ,Kubernetes Several other containerization technologies are also supported , such as containered、CRI-O etc. .

3、Kubernetes Architecture of

    Kubernetes Architecture can be divided into two parts ： Control panel and work node . The specific composition is shown in the figure below , Here you just need to have a general impression , We'll learn more about it later .

apiserver： yes Kubernetes The entry point for cluster operations , The external operation instruction comes first apiserver, Then it sends instructions to specific nodes / Service

etcd： yes Kubernetes Clustered distributed configuration data center , All cluster configurations exist there

Scheduler：Kubernetes The scheduler , Responsible for pod The distribution of

Controller Manager： Perform cluster level functions , For example, tracking work nodes 、 Handling failed nodes, etc

kubelet： And apiserver Communications , And manage the container of its node

kube-proxy： Responsible for the network communication of nodes

When the container executes （container runtime）: finger docker Wait for containerization