Master Docker: From Basics to Advanced Container Management

Quick Start

Docker originated as an internal side project at dotCloud, written in Go, aiming to provide a lightweight OS‑level virtualization solution based on Linux containers (LXC). Containers start in seconds, use resources efficiently, and allow thousands of instances on a single host.

Compared with traditional VM virtualization, containers share the host OS kernel, resulting in faster startup and higher resource utilization.

Installation

Official Docker packages are available for Mac, Linux and Windows; follow the official documentation. The graphical tool Kitematic (Visual Docker Container Management on Mac & Windows) can help beginners.

Daemon

Run the Docker daemon with a custom bind address, e.g. sudo /usr/bin/docker -d -H tcp://0.0.0.0:2375, or set export DOCKER_HOST="tcp://0.0.0.0:2375" to avoid typing the full command each time.

GUI tools

Web management interfaces such as Shipyard and Portainer simplify container operations.

Basic Concepts

Image : a read‑only template stored in a layered UnionFS; used to create containers.

Container : a runnable instance of an image with an additional writable layer; isolated filesystem, process space, and network.

Registry : a service that stores images (public Docker Hub, private registries, Docker Pool, etc.). Images can be pushed and pulled using docker push and docker pull.

Docker enables consistent development, testing, and deployment across environments.

Common Commands

Check Docker status: sudo docker info List running containers: docker ps (add -a for all, -l for the latest)

Running Containers

Example: docker run ubuntu:14.04 /bin/echo 'Hello wdx!' prints the message.

Interactive mode: docker run -t -i ubuntu:14.04 /bin/bash (‑t allocates a pseudo‑TTY, ‑i keeps STDIN open).

Inside the container you can inspect processes with ps or top, view /etc/hosts, check network with ip a, etc.

Images

Pull images with docker pull ubuntu:12.04 or from a custom registry. List local images using docker images. Build custom images with a Dockerfile and docker build -t myimage ..

Running Images

Search Docker Hub for images such as whalesay and run them: docker run docker/whalesay cowsay boo.

Creating Images

Write a Dockerfile, e.g.:

FROM docker/whalesay:latest
RUN apt-get -y update && apt-get install -y fortunes
CMD /usr/games/fortune -a | cowsay

Build with sudo docker build -t wdx-whale . and run docker run wdx-whale.

Managing Images

Export an image: docker save -o wdx-local-whale.tar wdxtub/wdx-whale. Import with docker load --input wdx-local-whale.tar. Delete dangling images with sudo docker rmi $(docker images -q -f "dangling=true").

Container Lifecycle

Start containers in background with -d. View logs using docker logs <containerid>. Stop with docker stop <containerid>, restart with docker restart <containerid>. Export a container with docker export <containerid> and import it as an image with docker import.

Registries and Repositories

A repository stores images; a registry is the server that hosts one or more repositories. Public Docker Hub is the most common registry.