How to understand docer?

Docker can be said to be a terminal command line virtual machine, but more accurately, it should actually be a virtual environment.

(Recommended tutorial: docker tutorial)

For example, do you want to use Linux seamlessly on your PC? Then virtual machines are not your only way out, you also have Docker! I prefer to call Docker a container. Of course, this is just a narrow interpretation of Docker. Docker is more than a container.

Docker contains 3 important concepts, which are:

1. Image (Image)

The image is static and can be shared by users. document.

Those of us who have played with dual systems and virtual machines all know that first you need an .iso image to install the system. The same is true for images in Docker. The image is static and you cannot operate it. You can only pull other people's images or push your own images.

2. Container

The image is static and inoperable and can only be shared and downloaded. So what can be operated?

is the container. Containers can be understood as the dynamic state of the image, which is the state of the system in our virtual machine after it is installed. In fact, it is wrong to say this. The most suitable description of the container should be the Live CD mode of the Linux iso file.

For example, when we played dual systems, we all entered Live CD mode, directly entering the system without installing the system. Docker containers are exactly the same concept, but they are lighter, faster and more convenient. But the disadvantage of Live CD is that all the modified and installed software you make after shutting down will be lost. The same is true for containers. Once they are directly launched, all previously installed gcc, vim, etc. will be lost.

If you want to save the changes, you need to encapsulate the current container into a new image, so that the previous changes will still be there after the new image is started next time.

3. Repository

I don’t know if you are familiar with git. The repository in Docker is very similar to the git code repository. You can pull it before pushing it. The image of your own warehouse can be moved locally, or you can pull the image pushed by others to the public warehouse to your local area. To put it bluntly, it is just like Baidu Cloud Disk. You can upload (push) the Docker environment you have created yourself, or you can download (pull) it. Mirror your own cloud to local.

At the same time, we know that the biggest feature of Baidu Cloud is sharing. Similar to Docker, if you get the Baidu Cloud sharing link (other people’s image name, label and other people’s user name), you can also download (pull) others Share the image locally and others can download (pull) your image because Docker repositories are public.

Of course, each free user has a quota to set one of his own images as private, which means that it is prohibited from being shared with others.

The above is the detailed content of How to understand docer?. For more information, please follow other related articles on the PHP Chinese website!