Docker Dive Part 1 — Basics
Why Dockers?
Dockers let the software install and run easily without thinking about setup and scaling.
What is Docker?
Eco-system or Platform for creating and running containers.
So, What is a Container?
A container is an instance of an image. We can create and run many containers out of one image. Each Container has its own isolated set of resources such as memory, networking, hard drive space etc.
Benefits of Container
Namespacing: Isolate resource per processes or groups.
Control groups: Limit amount of resources per processes.
What is an Image?
Simply, Single file with all the Configurations required to run a program.
Docker Ecosystem
We call Docker to all of these following. So don't get mess up. We need to clarify all.
Docker Commands
- DOCKER | RUN | <IMAGE NAME> — Download the docker image, Copy it into a container, run the container.
DOCKER RUN = DOCKER CREATE <imageNAME> + DOCKER START -a <containerID>
docker run hello-worldWhen we type the above command in the terminal, Its 1st identified by Docker client, Then Docker client asks the Docker Server to download the specified image (e.g: hello-world) from Docker Hub to the machine.
Docker Hub is a public repository of Docker images available online.
- DOCKER | RUN | <IMAGE NAME> | <COMMAND> — download, run plus run the command inside the container.
docker run busybox echo hiThis is will download Doker image “busybox” to local machine and execute the echo hi command against the container. Btw command should be to execute inside the container to give results. Else it will give errors as following.
docker: Error response from daemon: OCI runtime create failed:- DOCKER | PS — Show running containers.
docker run busybox ping google.comrun above command and type docker ps.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4cbffad75d91 busybox "ping google.com" 45 seconds ago Up 44 seconds awesome_stonebrakerIf we run `docker run hello-world echo hi`, container `echo hi` and stop its work. So container moves to exit state.
