Docker for absolute beginners - El Kitapçığı

    Docker for absolute beginners - El Kitapçığı

    2022, Mar 03    

    Introduction

    This handbook aims to teach docker basics.

    Starting

    Docker Version

    $ docker --version

    Starting docker

    $ systemctl status docker
$ systemctl start docker
# or
$ sudo dockerd
$ sudo dockerd --debug # Start docker service in debug mode

    Testing Docker

    $ docker run hello-world

    Containers

    Show all containers

    $ docker container ls
$ docker container ls -a

    Looking Active Containers

        $ docker container ps

    Show All Running Containers (included if they run)

    $ docker ps -a

    Detach Mode

    $ docker run -itd ubuntu
$ docker ps

    Stopping running docker

    $ docker stop <id or name>
$ docker ps -a

    Removing Container

    $ docker rm <id or name>

    Remove All Containers

    $ docker container prune

    Execute a Command on Running Container

    $ docker run -itd ubuntu
$ docker exec -it <id or name> /bin/bash
// without interactive mode
$ docker exec <id or name> ls

    Images

    Show Docker Images

    $ docker images
$ docker image ls

    Removing Images

    $ docker rmi <image name>
$ docker image rm <image name>
$ docker image prune # removes all dangling images

    Just Download a Docker Image

    $ docker pull <image name:version>

    Inspect

    Container

    $ docker container ls
$ docker inspect <container id>

    Image

    $ docker image ls
$ docker image inspect <image id>

    Docker Example - Jenkins

    For download Jenkins

    $ docker pull jenkins
$ docker image ls
$ docker image inspect <jenkins image id>
# map port
$ docker run -d -p 80:8080 jenkins/jenkins
$ docker ps

    Docker Networks

    List or Delete Networks

    $ docker network ls
$ docker network rm <network id>

    Delete Dangling Networks

    $ docker network prune

    Bridge Network (Default)

    $ docker run ubuntu

    None Network

    $ docker run ubuntu --network=none

    Host Network

    $ docker run ubuntu --network=host

    Custom Network

    $ docker network create --driver=bridge --subnet=182.1.0.1/16 isolatedNetwork
$ docker network ls
$ docker network inspect <network id>
$ docker run -itd --name=testUbuntu --net=isolatedNetwork ubuntu
$ docker inspect <container id or container name>
$ docker container inspect <container id or container name>

    Connect / Disconnect a container into a network

    $ docker network connect <network name> <container id>
$ docker network disconnect <network name> <container id>

    Communicating Between Two Docker Containers

    Stop All Containers

    $ docker stop $(docker ps -aq)

    Delete All Containers

    $ docker rm $(docker ps -aq)

    Example

    $ docker network create --driver=bridge --subnet=182.0.1.1/16 isolatedNetwork
$ docker run -itd --name=base centos
$ docker run -itd --name=test1 --net=isolatedNetwork centos
$ docker ps
$ docker exec -it base /bin/bash
	//inside $ ping test1
$ docker network connect isolatedNetwork base
$ docker exec -it base /bin/bash
	//inside $ ping test1
$ docker network disconnect isolatedNetwork base
$ docker exec -it base /bin/bash
	//inside $ ping test1

    Docker Volumes

    /var/lib/docker

    $ docker volume create data_volume
$ sudo ls /var/lib/docker/volumes -lrt
$ sudo ls /var/lib/docker/volumes/data_volume -lrt
$ sudo ls /var/lib/docker/volumes/data_volume/_data -lrt

    /www directory in the container

    $ docker run -itd --name=base -v data_volume:/www ubuntu
$ docker exec -it base /bin/bash
	$ ls -lrt

    Docker Bind Volumes

    $ mkdir data
$ docker run  -itd -v /home/ryhme/data:/www ubuntu
$ docker run --mount type=bind,source=/home/rhyme/data,target=/www ubuntu

    How to add a volume to an existing Docker container?

    $ docker ps  -a

CONTAINER ID        IMAGE                 COMMAND                  CREATED              STATUS                          PORTS               NAMES
5a8f89adeead        ubuntu:14.04          "/bin/bash"              About a minute ago   Exited (0) About a minute ago                       agitated_newton

$ docker commit 5a8f89adeead newimagename
$ docker run -ti -v "$PWD/somedir":/somedir newimagename /bin/bash

    Extra Information

    Starting a Test Container

    To use the docker exec command, you will need a running Docker container. If you don’t already have a container, start a test container with the following docker run command:

    $ docker run -d --name container-name alpine watch "date >> /var/log/date.log"

    This command creates a new Docker container from the official alpine image. This is a popular Linux container image that uses Alpine Linux, a lightweight, minimal Linux distribution.

    We use the -d flag to detach the container from our terminal and run it in the background. --name container-name will name the container container-name. You could choose any name you like here, or leave this off entirely to have Docker automatically generate a unique name for the new container.

    Next we have alpine, which specifies the image we want to use for the container.

    And finally we have watch "date >> /var/log/date.log". This is the command we want to run in the container. watch will repeatedly run the command you give it, every two seconds by default. The command that watch will run in this case is date >> /var/log/date.log. date prints the current date and time, like this:

    Output
Fri Jul 23 14:57:05 UTC 2021

    The >> /var/log/date.log portion of the command redirects the output from date and appends it to the file /var/log/date.log. Every two seconds a new line will be appended to the file, and after a few seconds it will look something like this:

    Output
Fri Jul 23 15:00:26 UTC 2021
Fri Jul 23 15:00:28 UTC 2021
Fri Jul 23 15:00:30 UTC 2021
Fri Jul 23 15:00:32 UTC 2021
Fri Jul 23 15:00:34 UTC 2021

    In the next step we’ll learn how to find the names of Docker containers. This will be useful if you already have a container you’re targeting, but you’re not sure what its name is.

    Finding the Name of a Docker Container

    $ docker ps

    Running an Interactive Shell in a Docker Container

    $ docker exec -it container-name sh

    Running a Non-interactive Command in a Docker Container

    $ docker exec container-name tail /var/log/date.log

    Running Commands in an Alternate Directory in a Docker Container

    $ docker exec --workdir /tmp container-name pwd
Output
/tmp

    Running Commands as a Different User in a Docker Container

    $ docker exec --user guest container-name whoami
Output
guest

    Passing Environment Variables into a Docker Container

    $ docker exec -e TEST=sammy container-name env
Output
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=76aded7112d4
TEST=sammy
HOME=/root

    To set multiple variables, repeat the -e flag for each one:

    $ docker exec -e TEST=sammy -e ENVIRONMENT=prod container-name env

    If you’d like to pass in a file full of environment variables you can do that with the --env-file flag.

    First, make the file with a text editor. We’ll open a new file with nano here, but you can use any editor you’re comfortable with:

    $ nano .env

    We’re using .env as the filename, as that’s a popular standard for using these sorts of files to manage information outside of version control.

    Write your KEY=value variables into the file, one per line, like the following:

    # Filename .env
TEST=sammy
ENVIRONMENT=prod

    Save and close the file. To save the file and exit nano, press CTRL+O, then ENTER to save, then CTRL+X to exit.

    Now run the docker exec command, specifying the correct filename after --env-file:

    $ docker exec --env-file .env container-name env
Output
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=76aded7112d4
TEST=sammy
ENVIRONMENT=prod
HOME=/root
    Twitter Facebook Google+
    # Docker # Container # Handbook