Docker Containers Basics
What is a Docker Container?
A Docker container is a lightweight, standalone, executable package that includes everything needed to run a piece of software, including the code, runtime, system tools, libraries, and settings. Containers provide a consistent and portable environment for applications across different computing platforms.
Key Characteristics of Docker Containers
graph TD
A[Docker Container] --> B[Isolation]
A --> C[Portability]
A --> D[Efficiency]
A --> E[Scalability]
Characteristic |
Description |
Isolation |
Containers run in isolated environments |
Lightweight |
Minimal resource consumption |
Portable |
Can run consistently across different systems |
Scalable |
Easy to scale up or down |
Basic Container Operations
Creating a Container
To create a Docker container, you can use the docker run
command:
## Pull an Ubuntu image
docker pull ubuntu:22.04
## Run a container from the Ubuntu image
docker run -it ubuntu:22.04 /bin/bash
Container States
Containers can exist in different states:
stateDiagram-v2
[*] --> Created
Created --> Running
Running --> Paused
Running --> Stopped
Paused --> Running
Stopped --> [*]
Listing Containers
## List running containers
docker ps
## List all containers (including stopped)
docker ps -a
Container Lifecycle Management
Containers are designed to be ephemeral. They can be easily created, started, stopped, moved, and deleted. This approach supports microservices architecture and continuous integration/continuous deployment (CI/CD) workflows.
Best Practices
- Keep containers small and focused
- Use official images when possible
- Avoid running containers as root
- Implement proper container cleanup
Learning with LabEx
At LabEx, we provide hands-on Docker container management environments to help you practice and master container technologies effectively.