3 minutes, 9 Q&a let you know quickly what Docker is.

Both Google, Amazon, Microsoft, and VMware are embracing the new era of cloud virtualization from Docker and container, both of which are emerging trends in the IT community. What exactly is Docker and container? Here are 9 q&a to tell you.



is Q1:container technology and server virtualization the same technology?

A:No. While both are virtualization technologies, the goal is to package the execution environment required for a set of applications, to create an isolated environment that facilitates moving across different hardware, but with a distinct operational mindset. In simple terms, common traditional virtualization technologies such as vsphere or Hyper-V are operating system-centric, while container technology is an application-centric virtualization technology.

Traditional virtualization technology from the operating system layer, the goal is to create a full set of operating systems can be used to execute a sandbox independent execution environment, accustomed to virtual machine (VM) to address. The container technology is a direct application of the relevant program code, function library, environment configuration files are packaged to establish a sandbox execution environment, in order to differentiate with the virtual machine generated by traditional virtualization technology, the environment container technology is called container.



Q2: What is the difference between a typical virtual machine and a container?

A:The most obvious difference is that the virtual machine needs to install the operating system (install guest OS) in order to execute the application, and the container does not need to install the operating system to execute the application. Instead of building a virtual environment outside the OS, container technology creates a virtual execution environment in the core system layer within the OS, replacing the functionality of a guest OS with the practice of sharing the host OS. Container is also known as the OS Layer virtualization technology.



Q3: Why containeris lightweight virtualization technology?

A:Because container technology takes the practice of sharing the host OS without having to execute the guest OS within each container, establishing container does not need to wait for the operating system to boot, not 1 minutes or a few seconds to enable it. It's faster than a traditional virtual machine that takes a few minutes or even a few 10 minutes to open.



is Q4:container technology a new technology ?

A:No, back in the 1982, the chroot mechanism built into UNIX systems was also a container technology. Other, such as the 1998-year FreeBSD jails, the 2005 Solaris Zones and OpenVZ, or a sandboxie mechanism like Windows 2004, belong to the practice of establishing an isolated virtual execution environment within the operating system, Can be called the container technology.

It was not until 2013 that DotCloud, the PAAs service company, released a set of container-standardized platform Docker, which was popular, so DotCloud decided to launch a new company in the name of Docker.



Q5:docker How to achieve container standardization?

A:Docker uses the Aufs file system to design a container image file that can layer the stack, wrapping all the programs in the container (including applications, related function libraries, configuration files) into Docker images, A dockerfile configuration file is provided to record each step of establishing the container process including parameters. As long as in any environment that supports Docker platforms, it is possible to create an identical container from this image to execute the same application. As a result, the application is able to move the program execution environment to any Docker-enabled environment, either through Docker images or even just dockerfile. Docker also releases APIs that can be used to control all container-related directives, and anyone who uses the same set of Docker will have the same set of methods for managing and building container, which is tantamount to standardizing container usage.



Q6: How many applications can be installed in a container image file?

A:Multiple programs can be installed in a container image file, such as Ubuntu, Apache, MySQL, node. js, Ruby, and so on. However, the Docker official recommends that a program be installed in a container and then iterate over the container to provide a complete service.

Docker calls this a new software architecture for MicroServices (microservices) that will make up every stack of an application and disassemble it into many small services, such as Apache services, MySQL Services, node. JS Services, and Ruby services. Each service is a program that is wrapped in container, such as MySQL service, which is deployed in container.

The advantage of this is that you can build a loosely coupled elastic application architecture and easily externally one of the container, for example, to upgrade MySQL and simply reload the new MySQL container image file to complete the database upgrade without shutting down the entire application system.



The OS is not required in Q7:container, why do I need an OS base image file?

A: The purpose of the OS base image file is for container to have the OS's filesystem, such as using Ubuntu's underlying image file to allow container to build the Ubuntu root schema instead of executing an OS execution instance.



How does Q8:docker help DevOps?

A: because Docker records every step of establishing a container image file through Dockerfile, it can be fully documented by the process and configuration parameters that establish the application execution environment. Dockerfile can be used to communicate the discussion of the execution environment between the developer and the OPS staff. Even with version control services such as GitHub, Dockerfile has versioning capabilities that can be managed with the infrastructure programmed (Infrastructure as code).



Q9: Can I perform Docker in a windowsserver environment?

A: not yet. Currently Docker can only be executed on Linux platforms, but Microsoft announced in October that it will build a Docker engine in the next wave of Windows Server revision, and that the same Docker image can span Linux and Windows OS in the future. More details are needed to be disclosed by Microsoft.

3 minutes, 9 Q&a let you know quickly what Docker is.