Kubernetes Introduction
Kubernetes is a container cluster management system. It is an open source platform that can realize automatic deployment, automatic expansion and contraction, and maintenance of container clusters.
With Kubernetes you can:
- Rapid application deployment
- Expand applications quickly
- Seamless connection with new application functions
- Save resources and optimize the use of hardware resources
Its goal is to promote an ecosystem of components and tools to reduce the burden of applications running in public or private clouds.
Kubernetes features
- Portable : Support public cloud, private cloud, hybrid cloud, multi-cloud
- Extensible : modular, plug-in, mountable, combinable
- Automation : automatic deployment, automatic restart, automatic replication, automatic scaling/scaling
Kubernetes was created and managed by Google in 2014 and is an open source version of Google’s large-scale container management technology Borg for more than 10 years.
Why containers?
Why use containers? Compare through the following two figures:
The traditional way of application deployment is to install applications through plug-ins or scripts. The disadvantage of this is that the application’s operation, configuration, management, and all life cycles will be bound to the current operating system. This is not conducive to application upgrades/rollbacks and other operations. Of course, it can also be achieved by creating a virtual machine. Certain functions, but the virtual machine is very heavy and not conducive to portability
The traditional way of deploying applications is by using a script or plug-in to install the application. The disadvantage of this process is that the entire application’s process, configuration, management, and life cycle will be stuck on the current operating system. This is not a great environment for application upgrades/rollback and other operations. In addition to “impossible” there is also a “virtual” way of doing the problem. Software inside the device contains certain functions, but it is too bulky and heavy to be portable.
In the new method, containers are deployed in the patients. Each container is isolated from any other container. Each container has its own level of organization. The processes of the two containers will not interrupt each other, and you can distinguish the computing resources. Modern containers can be deployed much quicker than virtual machines. Because containers are decoupled from the underlying facilities and machine file systems, they can be migrated between different clouds and different versions of operating systems.
Summary of container advantages:
- Quickly create/deploy applications: Compared with VM virtual machines, container image creation is easier.
- Continuous development, integration and deployment: Provide reliable and frequent container image construction/deployment, and use fast and simple rollback (due to image immutability).
- Separation of development and operation: Create container images in the build or release phase to decouple applications and infrastructure.
- Development, testing and production environment consistency: the consistency of running on the local or external network (production environment).
- Cloud platform or other operating systems: It can run in Ubuntu, RHEL, CoreOS, on-prem, Google Container Engine or any other environment.
- Loosely coupled, distributed, elastic, and microservice-oriented: The application is divided into smaller, independent components that can be dynamically deployed and managed.
- Resource isolation
- Resource utilization: more efficient
What can I do with Kubernetes?
Containerized applications can be run on physical or virtual machine Kubernetes clusters. Kubernetes can provide a “ container-centric infrastructure “ to meet some common requirements for running applications in a production environment, such as:
- Multiple processes (running as containers) work together. (Pod)
- Storage system mount
- Distributing secrets
- App health check
- Copy of application instance
- Pod auto scaling/expansion
- Naming and discovering
- Load balancing
- Rolling update
- Resource monitoring
- Log access
- Debug application
- Provide authentication and authorization
Kubernetes concepts and terminology
Functionally, I roughly divide the concepts or terms of Kubernetes into the following three categories:
Article Directory
kubernetes architecture diagram
Master
Node
Pod
Label
Replication Controller
Deployment
Horizontal Pod Autoscaler
StatefulSet
Service
Job
Volume
Persistent Volume
Namespace
Annotation
ConfigMap
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