Docker notes #1

The original Docker logo

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I am not a devops engineer means that I am not into the deployment things, however, I want to learn about the Docker. Also I want to utilize it in the development setup on our software team.

Therefore, I have started to learn it from the ground. I will publish my notes about it in the process.

General info

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• Unlike the virtualization, Docker has containerization. Containers share the same kernel of the host.

• It's much faster and lightweight compared to virtualization.

• Docker has public images you can download and use. Example: docker run centos uses the official image centos. If it's not installed in the host, it will download from the docker hub.

• Docker containers exit automatically after running if there is no running process left.

Commands

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docker ps

Shows the running containers

docker ps -a

Shows all containers including the exited ones.

docker rm <container_id_or_name>

Removes the container. Tip: You don't need to write IDS full, write a couple of chars from the beginning.

Example:

➜  ~ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                      PORTS               NAMES
b26772f74f32        ubuntu:14.04        "/bin/bash"         3 seconds ago       Exited (0) 14 seconds ago                       xenodochial_hoover
2b8393811355        ubuntu:14.04        "/bin/bash"         6 seconds ago       Exited (0) 17 seconds ago                       determined_agnesi
➜  ~ docker rm 2
2
➜  ~ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                      PORTS               NAMES
b26772f74f32        ubuntu:14.04        "/bin/bash"         11 seconds ago      Exited (0) 23 seconds ago                       xenodochial_hoover

docker images

Shows the installed images

docker rmi <image>

Removes the image. If there is a container running based on the image, you need to stop the container first.

docker pull image

Pulls the image from docker hub. It can be also username/imagename for unofficial images.

docker stop <container>

Stops the running container.

docker run <container> <command>

Starts a container and runs the command.

Ex: docker run ubuntu:14.04 cat /etc/*release*

Note: if you want to run in detached, use -d param.

docker exec <container_id> cat /etc/passwd

Execute commands on running containers.

docker run -it <image>

Creates a container from the image, runs an interactive TTY. (shell)