Docker Foundation Summary
- Docker client and server (daemon)
- Docker image
- Docker container
Docker container is built on the mirror above, we can understand the image as a defined class, and the container is an instance, a class can instantiate a lot of examples, the same docker can also run on the mirror multiple containers, each The container can be the same or it can be customized. Docker client and server can run on the same host, can also be different.
The registry is used to store the user’s image, which is divided into public and private. Docker company operating public registry called docker hub, the user can docker hub registered account, share and save their own mirror.
Docker can run on Linux, Mac, Windows.
Go to the official website to download the installation package.
download after the direct installation, the installation is completed after the run docker run hello-world, if no error, indicating a successful installation.
Install docker on Linux
Start the docker daemon:
Docker basic command
The docker base command contains the docker operation, the mirror operation, the container operation, and other related operations. Here are some common commands, please refer to the official documentation, or use the -help command.
View the docker information
View the docker version
Local images are stored in the /var/lib/docker directory.
View the local mirror list:
Other mirroring operations:
Create a container:
- -rm Once the process exits, the container is deleted
- -ti Enter interactive mode
- Ubuntu container based on the mirror name
- /bin/bash The command to run
- -d running in the background
- -p mapping of the port, the former for the machine, after the container
- -name custom name
Note: After creating the container, it will return an ID that is generated randomly.
Check container operating status:
View container-specific information:
More detailed than the ps-a command, including network information, configuration information, and other content, you can match with -format, such as:
View the process inside the container:
Into the container interior:
Or you can use:
Exec command can be executed inside the container command, the above code that the container to create a new shell.
The restart parameter can set the following:
- The Docker container is restarted regardless of the code program exiting the container
- On-failure You can specify an exit code
More container operation:
Container network management:
- Host mode, the use of dockerrun use -net = host specified (docker used in the network and the host is actually the same, in the container to see the network card ip is the host ip)
- Container mode, use-net = container: container_id/container_name (multiple containers using a common network, see ip is the same)
- None mode, specified with -net = none (in this mode, no network is configured)
- Bridge mode, specified with -net = bridge
- The default mode, do not specify the default is this network mode. (This mode assigns a separate Network Namespace to each container, similar to VMware’s nat network mode. All containers on the same host will be able to communicate with each other under the same network segment.)
Dockerfile can be used to dynamically generate a new image, for example, we pull a basic centos mirror, now need to install some of the software in this mirror, so that we can run the project code we prepared, then you can use the following two options:
Option 1: (manual)
In the centos mirror to create a container, enter the container interactive interface, manually install some of the necessary software, configure the environment. After doing all the changes, use the docker commit container-id newimagename to create a new image. Then use the new image to create the container, run our project code.
Option 2: (automatic)
The so-called automation, that is, do not need to enter the container manually enter the command to configure, everything is automatically handled when the container is running, then it will use the dockerfile. Dockerfile is simply a configuration file, docker container at run time will handle the contents of the file, such as the installation of software, modify the environment variables, run the program. The advantage of using dockerfile is that you can easily modify the contents of the configuration file to achieve the effect of creating dynamic images.
Create a dockerfile
We need to create a directory to store Dockerfile file, the directory name can be arbitrarily taken in the directory to create Dockerfile file. Here I am going to create a base based on centos mirror, the container will automatically open a python webserver (local monitor 8080 port) example.
Write a dockerfile
In the Dockerfile file to write:
The dockerfile syntax is similar to MakeDown, based on the following:
- FROM based on the base mirror name
- MAINTAINER maintainer information
- RUN run command (install software, etc.)
- CMD command to run the container (can only write one)
Grammar more than these, more content, you can refer to the official documents.
Generate dockerfile image
Into the directory where the Dockerfile file is located, run:
At this point, run docker images-a view, will find more than one image, named centos_test, tag 01 If dockerfile write a problem, in the build will be given, then you can docker run container id into the final state of the container to debug.
Use dockerfile to mirror
Run the container on this image:
At this point, open the machine 127.0.0.1:80
Each instruction must be in uppercase letters, such as FROM, RUN, and followed by content, docker file will be from the top down the order of the implementation of these content.
Role: set the working directory, similar to cd
You can override the container working directory with the -w parameter
Action: Set the environment variable
in the container to be overridden with -e.
Role: Specify what kind of user to run the container
You can use the docker-u to cover it.
Add and copy are used to add a file to the mirror, the difference is that copy can only copy the file, but no decompression function.