What is a host in docker

In docker, the host machine is also "Docker_Host", which is one of the overall architecture of Docker. It can be a physical machine or a virtual machine. A docker service is running on the host machine, using "docker daemon" "Can realize the life cycle management of docker objects.

The operating environment of this tutorial: linux7.3 system, docker-1.13.1 version, Dell G3 computer.

What is a host in docker

Docker can be imagined to a certain extent as a more lightweight computer with its own private operating system, network, and independent memory. And it provides strong enough packaging capabilities. Similar to the container analogy, we have packaged everything in one space. The host is the ship that pulls the box, and a packaged container is an independent existence. The underground ship can be changed at will, while the contents of the box remain unchanged. With this capability, Docker can run a software without tedious configuration of the host when installing the service. In the past, when we developed a java program, the host must provide a jre environment. If there is no such environment, unfortunately the program cannot be executed. With the container, this is easy. Pull an image, run it, and end it.

The overall architecture of Docker is divided into three parts, Clint, Docker_Host, Registey:

• Clinet: Same as mentioned above, it is the command line operation interface. By using the API interface, communication with the Doceker daemon is completed.

• Docker_Host: Docker's host machine can be a physical machine or a virtual machine. A docker service runs on it. We use docker daemon to realize the life cycle management of docker objects.

• Registey: docker registry strictly speaking does not belong to docker. It is another warehouse service and is the storage center for docker images. The official warehouse of docker is docker hub. We create it ourselves. For the convenience of the development team, we will maintain a warehouse, which we generally use harbor to implement.

There is a core in Docekr called Docker Engine. What is this? Just think of it simply as a C/S service, or more generally, it's a software. The overall architecture diagram is as follows:

Here is a brief introduction to some of its core concepts. The content not mentioned is too complicated and will be discussed later. Detailed description:

Server: The core part of the entire structure, the real executor of the command, inside which lives the docker daemon, which is simply a guardian docker daemon, running for a long time, resident in the memory , responsible for creating and managing dockers objects, such as images, containers, networks and volumes. You can find a process called dockerd in Linux.

Rest Api: Just like its name, it is an interface provided to the outside world. These interfaces can be used to call and execute the docker service and complete communication with the daemon.

Client: The outermost command line interface (CLI).

Recommended learning: "docker video tutorial"

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