Kubernetes in-depth understanding of kubernetes (I)

Traditional classification of cloud computing

---

The cloud itself is designed to meet the needs of a class of computing abstractions

The earliest clouds were basically iass layer , So-called iass Layer is used to manage the infrastructure layer , Provide an operating system one by one , The business only needs to be deployed on the operating systems one by one , Of course, these are virtual machines . What problems will this bring ？ Applications are operating system oriented , It separates a lot of things , For example, how can a highly available application be deployed to different nodes ？ These have to be concerned at the application level , If only give me the operating system , Then every company should solve the corresponding problems .

Later, whether the intermediate level can be abstracted , Manage the operating system , Middleware management , Runtime management , I'll help you set up the whole platform , All you need to do is run your application . This is it. pass Is in the iass Improve on .

The latter is whether we can focus on software , Application centric , Provide a software , Then you just need to use the software , This is it. sass, Provide some software for you to use directly .

 

Kubernetes The ecological system

---

kubernetes To break the iass sass pass, The boundary is not so clear , because Kubernetes Based on these standards api, To describe all escrow objects , These objects drill down to the infrastructure , Upward exploration is the application of abstraction .

  It is through unity api Unify the objects at all levels , The reason why it is vague , Because it goes down iass, You can put the whole iass Connect in , There is a powerful pass, With pass Then there are application-oriented , So it can provide sass service .

Kubernetes Design concept

---

 

The application supports stateful replica sets and stateless replica sets , To ensure high availability of applications .

k8s It is also highly available , Plane components can be deployed as highly available when they are built .

 

 

 

Layered architecture

---

 

 

kubernetes Several interface abstractions are implemented downward , One is called cri runtime abstract , The following can be accessed docker containerd, You can also pick up crio, Down is more right plugin Support for , And flexibility of choice , bring kubernetes It can run in different environments .

 

 

API Design principles

---

 

 

 

 

 

Kubernetes How to complete business description through object composition

---

  Through one deployment Create a business deployment object ,deployment control Will build replicaset,replicaset Will build pod,pod Will be bound by the scheduler , This is part of the business deployment description , The object involved is the time when the business is to be released , I want to define a service,service After creating kube-proxy It will be configured with various load balancing configurations and dns The domain name service will be configured for it , To publish a service, I need to define a service object ,service You can go through it again ingress A traffic entry to publish to the entire cluster data surface API Inside the gateway .

Therefore, the description of the whole business deployment is completed through the combination of various objects .

 

 

 

Architecture design principles

---

Here's another point , Only api server Be able to access etcd, Other services can only be provided through apiserver To access the cluster .

We encourage event monitoring , Instead of polling ,etcd and apiserver Can support event notification , You don't need to poll , The polling query puts etcd and apiserver Pull dead , Why do I need to listen , Because you need to keep a long connection , All objects change frequently , Changes to these objects make etcd and apiserver Take the initiative to issue , Instead of polling over and over again .

 

 

guide （Bootstrapping） principle

---

Can I use kubernetes management kubernetes Control plane , It's called self-hosting, adopt kubernetes Component handle kubernetes Some basic components , That is the whole kubernetes Pull it up , This is the same. kubeadm To load the cluster , It passes through kubelet In a static state pod To load the entire cluster , This is it. self-hosting.

Can I use binary to build a cluster , Sure , Learn... In your early days kubernetes You should understand how each service is configured , It's a very good way , However, this is not recommended in production clusters , since kubernetes It can ensure the high availability of applications , Then we can use kubernetes To manage kubernetes The plane itself ,kubernets on kubernets It's a very good way .