Introduction
Docker is nowadays a buzz word, I heard this everywhere in software development sector. I went through it to learn what it actually it and why do we need it. First of all, before we go into need of docker, we have to know about virtual machines. Yes, docker is kind of virtual machine, but virtual machines are bloated, need more resources. That means we can run many instances of docker compared to virtual machines in the same system.
The lightweight nature of docker instances has several advantages such as more customized configuration, and also application portability. The application can be deployed into docker and can be packed and shipped anywhere. Because of this, the developers prefer docker to deploy their applications in a cloud.
Installation
The installation in Linux system is quite easy. I have just installed it into my Ubuntu 16.04 system using the following commands:
sudo docker run hello-world
Do Interesting Stuffs
After successful installation of docker, it is good idea to do something interesting. Docker comes with default image hello-world which does nothing but print a message. The image are blueprints of application which form the basis of containers. After we run images, creates a container which runs the actual application.
So, we need to download (or pull) the image first before we create instance of it. We do that by using "docker pull" command.
sudo docker pull busybox
Then, after pull completes, we can see the image using the following command:
sudo docker images
Now, we run the container
sudo docker run busybox
This creates container instance, since no command is given, it does nothing, and terminates the instance. If we do something like this:
sudo docker run busybox echo "hello world"
This will print out the hello world in the console.
Now, if we run the image using -it parameter (-it stands for interactive), then the instance does not terminate.
sudo docker run -it busybox
We can verify the running of this using the following command:
sudo docker container ls
This shows the running instances.
Remove instance
sudo docker rm container_id1, container_id2
or to remove all exited instances:
sudo docker rm $(sudo docker ps -a -q -f status=exited)
Remove image
sudo docker rmi image_id1, image_id2
or to remove all images
sudo docker rmi $(docker images -a -q)
Ubuntu 18.04
Now my interest is to pull ubuntu 18.04 image and create a container of it.
sudo docker pull ubuntu:18.04 (pull)
sudo docker images (check)
sudo docker run -it ubuntu:18.04 (run)
sudo docker container ls (verify container)
So, after running container you are in the bash terminal, where you have possibilities to install commands and tools from scratch.
There basic image does not come with all necessary command or tools. So, we have to install or configure ourselves.
Docker is nowadays a buzz word, I heard this everywhere in software development sector. I went through it to learn what it actually it and why do we need it. First of all, before we go into need of docker, we have to know about virtual machines. Yes, docker is kind of virtual machine, but virtual machines are bloated, need more resources. That means we can run many instances of docker compared to virtual machines in the same system.
The lightweight nature of docker instances has several advantages such as more customized configuration, and also application portability. The application can be deployed into docker and can be packed and shipped anywhere. Because of this, the developers prefer docker to deploy their applications in a cloud.
Installation
The installation in Linux system is quite easy. I have just installed it into my Ubuntu 16.04 system using the following commands:
- Add public key into your system
- Add repository
- Update packages
- Install docker community edition ( I am afraid to install enterprise edition, I hope it is also free, but I like the word community)
- Test installation
sudo docker run hello-world
Do Interesting Stuffs
After successful installation of docker, it is good idea to do something interesting. Docker comes with default image hello-world which does nothing but print a message. The image are blueprints of application which form the basis of containers. After we run images, creates a container which runs the actual application.
So, we need to download (or pull) the image first before we create instance of it. We do that by using "docker pull" command.
sudo docker pull busybox
Then, after pull completes, we can see the image using the following command:
sudo docker images
Now, we run the container
sudo docker run busybox
This creates container instance, since no command is given, it does nothing, and terminates the instance. If we do something like this:
sudo docker run busybox echo "hello world"
This will print out the hello world in the console.
Now, if we run the image using -it parameter (-it stands for interactive), then the instance does not terminate.
sudo docker run -it busybox
We can verify the running of this using the following command:
sudo docker container ls
This shows the running instances.
Remove instance
sudo docker rm container_id1, container_id2
or to remove all exited instances:
sudo docker rm $(sudo docker ps -a -q -f status=exited)
Remove image
sudo docker rmi image_id1, image_id2
or to remove all images
sudo docker rmi $(docker images -a -q)
Ubuntu 18.04
Now my interest is to pull ubuntu 18.04 image and create a container of it.
sudo docker pull ubuntu:18.04 (pull)
sudo docker images (check)
sudo docker run -it ubuntu:18.04 (run)
sudo docker container ls (verify container)
So, after running container you are in the bash terminal, where you have possibilities to install commands and tools from scratch.
There basic image does not come with all necessary command or tools. So, we have to install or configure ourselves.
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