Welcome! We are excited that you want to learn Docker. The Docker Get Started Tutorial teaches you how to:
Docker is a platform for developers and sysadmins to develop, deploy, and run applications with containers. The use of Linux containers to deploy applications is called containerization. Containers are not new, but their use for easily deploying applications is.
Containerization is increasingly popular because containers are:
A container is launched by running an image. An image is an executable package that includes everything needed to run an application--the code, a runtime, libraries, environment variables, and configuration files.
A container is a runtime instance of an image--what the image becomes in memory when executed (that is, an image with state, or a user process). You can see a list of your running containers with the command,
docker ps, just as you would in Linux.
A container runs natively on Linux and shares the kernel of the host machine with other containers. It runs a discrete process, taking no more memory than any other executable, making it lightweight.
By contrast, a virtual machine (VM) runs a full-blown “guest” operating system with virtual access to host resources through a hypervisor. In general, VMs provide an environment with more resources than most applications need.
For full Kubernetes Integration
docker --version and ensure that you have a supported version of Docker:
docker --version Docker version 17.12.0-ce, build c97c6d6
docker info (or
docker version without
--) to view even more details about your Docker installation:
docker info Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 0 Server Version: 17.12.0-ce Storage Driver: overlay2 ...
To avoid permission errors (and the use of
sudo), add your user to the
dockergroup. Read more.
Test that your installation works by running the simple Docker image, hello-world:
docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world ca4f61b1923c: Pull complete Digest: sha256:ca0eeb6fb05351dfc8759c20733c91def84cb8007aa89a5bf606bc8b315b9fc7 Status: Downloaded newer image for hello-world:latest Hello from Docker! This message shows that your installation appears to be working correctly. ...
hello-world image that was downloaded to your machine:
docker image ls
hello-world container (spawned by the image) which exits after displaying its message. If it were still running, you would not need the
docker container ls --all CONTAINER ID IMAGE COMMAND CREATED STATUS 54f4984ed6a8 hello-world "/hello" 20 seconds ago Exited (0) 19 seconds ago
## List Docker CLI commands docker docker container --help ## Display Docker version and info docker --version docker version docker info ## Execute Docker image docker run hello-world ## List Docker images docker image ls ## List Docker containers (running, all, all in quiet mode) docker container ls docker container ls --all docker container ls -aq
Containerization makes CI/CD seamless. For example:
With Docker, scaling your application is a matter of spinning up new executables, not running heavy VM hosts.
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