[Docker] Operation up to container creation # 2

Purpose of this post

・ Minutes of Docker operation.

Teaching materials used for learning

○ Create container (2. When creating image)

○ Creating build context

mkdir <build context name>

-The build context is the folder that is the source of the image when creating a docker image.

○ Move to build context

cd <build context name>

-Set the current directory to the build context state

○ Creating and editing Dockerfile

touch Dockerfile

-Create a text file called Dockerfile in the build context (this is a naming convention) -The command written in this is executed and an image is created (editing method is omitted because I will write a separate article)

○ Creating an image

docker build .

-"." Means the current directory (image creation is executed using the Dockerfile in the current directory) -Since the name and TAG are not specified, the image "none" is created. ・ Called dangling image

** [When explicitly specifying Dockerfile] **

docker build -f docker -f <Dockerfile path/name>

--F is an option to explicitly specify a Dockerfile -Enter the appropriate path and file name in the <Dockerfile path/name> part.

** [When creating by specifying the name and TAG] **

docker build -t <image name>:<TAG> .

-T is an option to create an image with a name ・ The part is usually written as latest.

○ Creating a container

docker run <image name>

-Specify the image name that is the source of the container you want to create and execute run -As explained in # 1, this will exit the container after executing the default command.

** [Overwrite the default command after run] **

docker run <image name> <Overwrite command>

-Execute the overwrite command instead of the default command -In this case, after executing the overwrite command, exit and exit from the container. -The default command can be confirmed from Command of docker ps -a after executing run. -If you overwrite, the Command specified here will be displayed.

** [Description to remain in the container after running] **

docker run -it <image name> bash

-Now stays in the container without exiting after launching the container -Therefore, the description before execution of the terminal changes as follows.

root@xxxxxxxxxxx:/#

・ This means that you can now access the OS on Container through bash. -By default, it becomes the root user after starting the container. -The process of exiting from Continaer by exit is not executed. -When exiting the container, execute the following to return to the terminal state of the Host.

exit

What is ○ -it?

docker run -it <image name> bash

-Commands that are often used to describe things that remain in the container after a run ・ Overlay -i and -t -it ・ Each has the following meanings

○-i ・ Input is possible -Command to connect STDIN (input ch) from HOST to container -If there is no connection, the input will only be transmitted to the Host, so the instructions will not reach the container.

[What is ch] ・ There are three types: "STDIN", "STDOUT", and "STDERR". ・ STDIN: ch for connecting keyboard input to the program -STDOUT, STDERR: ch to output the program result to the monitor

○-t ・ Terminal display becomes beautiful (prety) -Command storage can also be used