Previously, I discussed in detail about Docker's theoretical part and installation process. Before starting this coding part, if you don't know about docker, please read part 1 first click here. And if you already know about docker's basic knowledge, you're welcome to part 2.
Linux
I told you that I will teach you basic Linux commands that are needed only for docker. And I hope, it will be very helpful to start not only docker but also to run the Linux operating system. Open your terminal and type
sudo su
sudo super user do and su lets you switch user so that you're actually logged in as a root user.
pwd -> Used to find out the path of the current working directory(folder) you’re in.
cd -> To navigate through the Linux files and directories, use the cd command.
ls -> If you want to see the list of files on your Linux system, use the ls or ls -a command.
mkdir -> Use the mkdir command when you need to create a folder or a directory.
rmdir -> Use rmdir to delete a directory. But rmdir can only be used to delete an empty directory. To delete a directory containing files, use rm.
rm -> Use the rm command to delete files and directories.
touch —> The touch command is used to create a file.
cat -> we can create and concatenate( join) files.
vi -> text editor, you can modify and save file.
echo —> The echo command helps us move some data, usually text into a file.
cp — Use the cp command to copy files through the command line. It takes two arguments: The first is the location of the file to be copied, the second is where to copy.
mv — Use the mv command to move files through the command line. We can also use the mv command to rename a file.
sudo apt-get update -> It is good to update your repository each time you try to install a new package.
sudo apt-get upgrade -> You can upgrade the system
Docker 💥💥💥
image to container 🇧🇩
First of all, we want to create a container and to create a container we need an OS image. So, we pull an image from the docker hub. Before starting, we need root access, open terminal and run
sudo su
Start your docker service and run
service docker start
you can see docker information using docker info
However, at this time our goal is to create a container. We need an OS image and we want to take the Ubuntu OS image. For that, run
docker images
now see that we have no image so we want to pull an image from the docker hub. For that, run
docker pull ubuntu
Now see the real magic. It first searches on our local environment. But we have no ubuntu OS image and that's why it pulls from the docker hub and looks at the file size, it is only almost 28 MB! I already said that docker OS images are light in weight. After downloading and extracting, the file size stands around 72 MB! Now again run
docker images
This time you found an OS image. Congratulations! 1st step done. You can try to pull centos OS using docker pull centos
I told you, we have 3 ways to create an image. And one of them is done, pulling images from the docker hub.🔥
It's time to make a brand new container. Remember that we have ubuntu OS image, so run
docker run -it --name ubuntu_container1 ubuntu /bin/bash
wow! it is looking like some weird things😨. Okay, let me explain. Here run is a combination of create and start. On the other hand, -it means interactive mode with a terminal. Then if we want to give a name for a container, we have to use --name command then the container's name. In our case, container name is ubuntu_container1. After that, we have selected an image and /bin/bash always fixed here. So,
docker run -it --name container_name image_name /bin/bash
Now, you're in your container. Run ls on your terminal. You will see Linux directories. And it is now your development environment as like your personal computer. You can create and run your application in the container.
Else, you maybe noticed that we get a container ID besides of root@ on the terminal.
Now, create a file in your container by using
touch container1.txt
to see this file run ls command. You see! You've created a file in your container. Not only files but also any applications that you want to create and share with others, you can!
To exit or stop your current container, use exit command.
And to see your all containers, run
docker ps -a
You see all containers here but at this time we can see only one container and which is our ubuntu_container1. Carefully observe, here we found container ID, IMAGE (we used ubuntu, remember?), NAME etc. But if we want to see just running container, we just run docker ps At this time, we have no running container. Because we exit our container.
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container to image 🇧🇩
We have a container (ubuntu_container1), now we want to convert container into image. So that we can share our files or projects with others. Remember? in our container we created a file (container1.txt). And now we want to share it through an image. So run
docker commit ubuntu_container1 my_image1
Here, ubuntu_container1 is our container name that we want to convert into an image and my_image1 will be our new image name.
To see our new image, run
docker images
And boom 💥, do you see? In the image list, you see our my_image1 image file. Now you can create a container by using this image and you will find container1.txt file by running ls command that we created.
Again, to create a container by using this image, run
docker run -it --name ubuntu_container2 my_image1 /bin/bash
Now run ls you will find our container1.txt file 🤩.
Exit or stop your container by using exit command and run docker ps -a this time, you will find 2 containers, ubuntu_container2 is the recent one. And one was created by ubuntu image and the other was created by my_image1 image. Make sense?
Good to know
To enter an existing container, run
docker attach container_name
To delete a container
docker rm container_name/id
To delete an image
docker rmi image_id
To start an existing container but doesn't enter into the container
docker start container_name
To start an existing container
docker stop container_name
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upload image into docker hub 🇧🇩
To share your docker image with others, you have to upload your image into the docker hub. For that, first you have to create an account on hub.docker.com. Simple sign-up process! After successfully sign-up, back your terminal and run
docker login
then enter your username and password and if all is okay, it will show you Login Succeeded. And now you're ready to upload your image into the docker hub.
We need to tag our image. That mean's, we have to set a name that we want to store in our docker repository. so run
docker tag my_image1 sabbir185/my_image1
after tag, our container image name and then a name that we want to set to store our container image. For example, I set a tag name sabbir185/my_image1 for our container image my_image1.
Now run the push command to upload the image. After push command, needs tagged image name. And my case sabbir185/my_image1. Now hit enter
docker push sabbir185/my_image1
Refresh your docker hub profile, you will see an image. 🥳😎
Now, you can pull your docker image or share it with others. For example in my case, my docker image sabbir185/my_image1
If I want to pull my docker image, I just run
docker pull sabbir185/my_image1
Remember? I have already discussed it 🤩🥰.
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Dockerfile to image 🇧🇩
I told you, there are 3 ways to get an image. This is another method to gain a docker image and not only a popular one but also easy one of them. To create an image, first we have to create a Dockerfile, so run
touch Dockerfile
After that, open and write what you want to build. For my case, I want to create a ubuntu image and in image file, want to create a file name test1.txt. You have to open Dockerfile by
vi Dockerfile
And press i for write into the text editor.
FROM ubuntu
RUN echo "Welcome to docker" > /tmp/test1.txt
press Esc key and :wq then enter. Now run to build image
docker build -t image2 .
You can set any image name instead of image2
Check image
docker images
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Bonus talk
There are some other topics. For example docker volume, port/expose, docker-compose etc. But For a beginner, I think it's enough for you now. Practice it and then explore some advanced topics that you want.
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