[Practice] Docker images
docker commit- running container 를 docker image 로 만드는 방법
docker commit -m "message" -a "author" <container-id> <image-name>docker commit을 사용하면, 수동으로 Dockerfile 을 만들지 않고도 도커 이미지를 만들 수 있습니다.touch Dockerfile
Move to the docker-practice folder.
Create an empty file called Dockerfile.
이미지에 특정 패키지를 설치하는 명령어는 무엇입니까?
Answer: RUN
Translation: Let's look at the basic commands that can be used in Dockerfile one by one. FROM is a command that specifies which image to use as a base image for Dockerfile. When creating a Docker image, instead of creating the environment I intend from scratch, I can use a pre-made image such as python:3.9, python-3.9-alpine, etc. as the base and install pytorch and add my source code.
FROM <image>[:<tag>] [AS <name>]
# 예시
FROM ubuntu
FROM ubuntu:18.04
FROM nginx:latest AS ngx
The command to copy files or directories from the <src> path on the host (local) to the <dest> path inside the container.
COPY <src>... <dest>
# 예시
COPY a.txt /some-directory/b.txt
COPY my-directory /some-directory-2
ADD is similar to COPY but it has additional features.
# 1 - 호스트에 압축되어있는 파일을 풀면서 컨테이너 내부로 copy 할 수 있음
ADD scripts.tar.gz /tmp
# 2 - Remote URLs 에 있는 파일을 소스 경로로 지정할 수 있음
ADD http://www.example.com/script.sh /tmp
# 위 두 가지 기능을 사용하고 싶을 경우에만 COPY 대신 ADD 를 사용하는 것을 권장
The command to run the specified command inside a Docker container. Docker images maintain the state in which the commands are executed.
RUN <command>
RUN ["executable-command", "parameter1", "parameter2"]
# 예시
RUN pip install torch
RUN pip install -r requirements.txt
CMD specifies a command that the Docker container will run when it starts. There is a similar command called ENTRYPOINT. The difference between them will be discussed later. Note that only one CMD can be run in one Docker image, which is different from RUN command.
CMD <command>
CMD ["executable-command", "parameter1", "parameter2"]
CMD ["parameter1", "parameter2"] # ENTRYPOINT 와 함께 사용될 때
# 예시
CMD python main.py
WORKDIR is a command that specifies which directory inside the container to perform future additional commands. If the directory does not exist, it will be created.
WORKDIR /path/to/workdir
# 예시
WORKDIR /home/demo
RUN pwd # /home/demo 가 출력됨
This is a command to set the value of environment variables that will be used continuously inside the container.
ENV <KEY> <VALUE>
ENV <KEY>=<VALUE>
# 예시
# default 언어 설정
RUN locale-gen ko_KR.UTF-8
ENV LANG ko_KR.UTF-8
ENV LANGUAGE ko_KR.UTF-8
ENV LC_ALL ko_KR.UTF-8
You can specify the port/protocol to be opened from the container. If <protocol> is not specified, TCP is set as the default.
EXPOSE <port>
EXPOSE <port>/<protocol>
# 예시
EXPOSE 8080
Write a simple Dockerfile by using vim Dockerfile or an editor like vscode and write the following:
# base image 를 ubuntu 18.04 로 설정합니다.
FROM ubuntu:18.04
# apt-get update 명령을 실행합니다.
RUN apt-get update
# TEST env var의 값을 hello 로 지정합니다.
ENV TEST hello
# DOCKER CONTAINER 가 시작될 때, 환경변수 TEST 의 값을 출력합니다.
CMD echo $TEST
Use the docker build command to create a Docker Image from a Dockerfile.
docker build --help
Run the following command from the path where the Dockerfile is located.
docker build -t my-image:v1.0.0 .
The command above means to build an image with the name "my-image" and the tag "v1.0.0" from the Dockerfile in the current path. Let's check if the image was built successfully.
# grep : my-image 가 있는지를 잡아내는 (grep) 하는 명령어
docker images | grep my-image
If performed normally, it will output as follows.
my-image v1.0.0 143114710b2d 3 seconds ago 87.9MB
Let's now run a docker container with the my-image:v1.0.0 image that we just built.
docker run my-image:v1.0.0
If performed normally, it will result in the following.
hello
Let's run a docker container and change the value of the TEST env var at the time of running the my-image:v1.0.0 image we just built.
docker run -e TEST=bye my-image:v1.0.0
If performed normally, it will be as follows.
bye