What is Docker?

What is Docker?

Docker允许我们打包我们的应用以及其所有的依赖包到一个标准化单元中用于软件开发。

The Docker container packs an application into a finished file system that contains all the requirements that the app will run: Code, runtime, System tools, System library-anything you install on the server. This ensures that he will run in the same way, regardless of the environment in which it runs.

Features of Docker

• Light weight
  Containers running on a single machine share the same operating system kernel, so they can start immediately and use RAM more efficiently. Images are built by a tiered file system, so they can share common files, making disk usage and image downloads more efficient.
• Open
  Docker containers are based on open source standards, which enable containers to run on a number of mainstream Linux distributions and on Microsoft operating systems that support each infrastructure.
• Security
  Containers isolate each application and the underlying infrastructure and provide a layer of protection for the application.

What is the difference between Docker and virtual machine?

容器拥有与虚拟机相同的资源分离和分配的有点，但是一些不同的架构方法使得容器更加轻型和有效率。

Virtual machines

Each virtual machine contains the application, the necessary binaries and libraries, and a full user operating system-each virtual machine may need a size of 10Gb.

Container

The container contains the app and all of its dependent packages, but shares the kernel with other containers. They run in a separate process in the host operating system, in user space. They are also not tied to any particular infrastructure-Docker containers run on any computer, any device, and any cloud.

How can a container help us build better software?

当我们的app在Docker容器中的时候，我们不需要担心为每一种语言设置和维持不同的环境或不同的工具。我们只需专注于创建新的也行，修复问题和交付软件。

• Speed up Development
  Reduce the time wasted in setting up the development environment, break up new instances, and copy the product code to run locally. With Docker, we can replicate the living environment very simply and run any new endpoint running Docker.
• Enhance Creativity
  The isolation capabilities of Docker containers eliminate the fear of using "approved" language stacks and tools. Developers can use the best languages and tools for their app services without worrying about causing conflicts.
• eliminate inconsistencies in development
  By packaging an application and his configuration and dependencies, and delivering as a container, the application will always work in accordance with local design, whether in other applications, in testing, or in the product. No more worrying about installing the same configuration into a different environment.

Share simple, and apply collaboration

Docker创建一个用于开发和系统管理的通用框架，用于在分布式应用中工作。

Publish and share content

In the Docker hub your team stores, publishes and manages your Docker images. Image updates, changes and history are automatically shared through your organization.

Easier to share your app with others

Deliver one or more containers to other people or downstream teams, while tuition is concerned with the problems caused by different environmental dependencies. Other teams can easily connect or test your app without learning or worrying about how he works.

Faster delivery of more software

Docker允许你动态的修改你的应用，例如添加新的功能，扩展服务来快速改变问题区域。

Delivery of more than 7X

Docker users deliver more than 7X of software on average after they deploy Docker in their environment. More frequent updates provide more value to your consumers.

Rapid expansion

Docker containers can be accelerated or slowed down in seconds, making it easier to extend application services at any time to meet user needs, and then simply slow down these containers and use those resources when you need resources.

Fix the problem more easily

Docker makes it easier to identify problems and isolate problem containers, quickly roll back the necessary modifications, and then update the containers into the product. Isolation between containers makes these changes less disruptive than traditional software models.

Now we can focus on building the app.

What is Docker?