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Docker Series 1: Basic

Posted on Edited on In Disqus:
This series is about Docker container related, I will share some practical tips in my daily work, and I hope some of them will help you too. Maybe some of the strategies you have already used may be useful, so I will share this series as a summary, the first part will introduce how to download and build image, how to start and stop container.

Preface

There are more than ten blogs in this serices. I won’t go into code of docker itself, but I will share some tips and tricks in my daily work. When I wrote these blogs, I usedDebian10, docker-ce=5:19.03.2~3-0~debian-buster

Install Docker

Please refer to offical document. If you are in China, maybe you need USTC’s source

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# A simple way to list available versions
$ apt-cache policy docker-ce

     5:19.03.2~3-0~debian-buster 500
        500 https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/debian buster/stable amd64 Packages
        100 /var/lib/dpkg/status
$ apt-get install docker-ce=5:19.03.2~3-0~debian-buster

Download and build images

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# download images
$ docker pull python:3.7.4-stretch

# list the images in the host
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
python              3.7.4-stretch       b9d77e48a75c        3 weeks ago         940MB

You can use docker build to create a new image.

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# make an empty directory
$ mkdir tmp && cd tmp

# create Dockerfile
$ cat > Dockerfile <<EOF
FROM python:3.7.4-stretch
RUN echo 1 > /tmp/file.txt
EOF

# start build
$ docker build . -t my_image

# now, you can get the image just built
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
python              3.7.4-stretch       b9d77e48a75c        3 weeks ago         940MB
my_image            latest              860d8f0fd1c4        25 seconds ago      940MB

Start and stop container

When we have images, we could use docker run to create a container.

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$ docker run -ti my_image /bin/bash
root@9b497582be91:/# 

# `docker ps` will display the container currently running
$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
9b497582be91        my_image            "/bin/bash"              44 seconds ago      Up 43 seconds                                magical_beaver
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# `docker stop` to stop a container

$ docker stop magical_beaver
magical_beaver


# `docker ps -a` will display all the containers, even we closed it.
$ docker ps -a                                                                                                                                                          
CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS                     PORTS                    NAMES
9b497582be91        my_image              "/bin/bash"              2 minutes ago       Exited (0) 4 seconds ago                            magical_beaver

How to execute a command in a running container

I use docker exec to attach a docker container.

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docker exec -ti <container_name> /bin/bash
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