1. Concept
① Cloud computing : It is a resource service model, which can obtain the required resources (such as networks, servers, storage, applications and services) from the shared pool of configurable computing resources conveniently and on demand anytime, anywhere. It can be quickly provisioned and released, greatly reducing the overhead of resource management.
②Classic cloud computing framework : including IaaS (Infrastructure as a Service, infrastructure as a service; services for infrastructure operation and maintenance personnel, providing computing, storage, network and other basic resources), PaaS (Platform as a Service, platform as a service; Serving application developers, providing software operating environment, related tools and services required to support application operation), SaaS (Software as a Service; for general users, providing a complete set of available software systems).
③ Docker : The Docker container is the basic unit of resource division and scheduling, and the entire software runtime environment is packaged. It is designed for developers and system administrators to build, publish and run distributed applications. It is a cross-platform, portable and easy-to-use container solution. The source code of Docker is hosted on Github, developed based on the Go language and complies with the Apache 2.0 protocol. Docker can quickly and automatically deploy applications inside containers, and provide resource isolation and security for containers through operating system kernel technologies (namespace, cgroups, etc.).
④The advantages of container technology :
1. Continuous deployment and testing . Containers eliminate online and offline environmental differences and ensure the environmental consistency and standardization of the application life cycle. Developers use images to build a standard development environment. After development, they migrate through images that encapsulate the complete environment and applications. Testing and operation and maintenance can be tested and released by deploying software images through quality inspection.
2. Cross-cloud platform support . Containers have their own adaptability. More and more cloud platforms support containers. Users no longer need to worry about being bound by cloud platforms, and it also makes multi-platform hybrid deployment possible.
3. Environment standardization and version control . We can use tools such as Git to perform version control on container images, and you can even implement version control for the entire application operating environment, which can be quickly rolled back in the event of a failure. Compared with previous virtual machine images, container compression and backup are faster, and image startup is as fast as starting a normal process.
4. High resource utilization and isolation . Containers do not have the extra overhead of hypervisors, and share the operating system with the underlying layer, resulting in better performance and lower system load. Under the same conditions, more application instances can be run, and system resources can be more fully utilized. At the same time, resources such as CPU and memory can be accurately allocated to applications to ensure that applications do not affect each other.
5. Container cross-platform and mirroring . Containers have a standardized set of configuration methods. Packaging the application and its dependent environment into an image truly realizes the concept of "build once, run everywhere".
6. Easy to understand and easy to use . A developer can get started with Docker, install and deploy in 15 minutes.
7. Apply the mirror library . Docker has officially built an image repository, which is organized and managed similarly to GitHub, and has accumulated thousands of images on it.
⑤Container cloud : The container is the basic unit of resource segmentation and scheduling, encapsulates the entire software runtime environment, and provides developers and system administrators with a platform for building, publishing and running distributed applications. Container cloud is not limited to Docker, the CoreOS project based on rkt container is also a container cloud. Google's kubernetes is a container cloud based on Docker technology.