Docker and basic operational commands

Docker is a tool designed to make it easier to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package.

Docker is a bit like a virtual machine. But unlike a virtual machine, rather than creating a whole virtual operating system, Docker allows applications to use the same kernel as the system that they're running on and only requires applications be shipped with things not already running on the host computer. This gives a significant performance boost and reduces the size of the application.

Docker is a tool which help containerizing the applications. It is a computer program that performs OS level virtualization, also known as Containerization.

Application containerization is an OS level virtualization method to deploy and run distributed applications without launching an entire virtual machines for each application. Below pic shows the construct and container engine is actually Docker.

Container doesn’t contain all the VM files but min which is needed for the app and uses the kernel of the VM that’s why its very small in size.

Above is the life cycle of the container below are the steps explained and command used :

There is central repo for docker images called dockerhub just like github.

• Pull image in your system from docker hub
• Run the image and it becomes container
• Stop container or you can remove container
• Do changes in the image or create your thing and save it with different name now its different image
• Login to the docker first by docker login
• Push the image to the docker hub with the naming convention username/image name

Below are few commands that you will use in daily ops :

Docker –version

Docker pull < image-name > [ To pull the image from the repo / hub]

Docker images [ To verify the images downloaded or pull]

Docker run -it -d < image-name > [run the image and make it a container]

Docker ps [ all the container running state on the server]

Docker ps -a [ show all the container running or not ]

Docker stop <container ID>  [ stopping container]

Docker exec  -it <container ID>  <bash/powershell>

Docker kill  <container ID>  [forcing to stop]

Docker stop <container ID>  [ stopping container]

Docker rm <container ID>  [ remove container from system ]

Docker rm <images ID>  [ remove images from system ]

Exit to get out of the contaimer

Docker commit <container ID >  < give name for image >

Docker push <imageid>  <imagename>