Docker

Docker Basics Cheatsheet

A concise Docker cheat sheet for beginners, covering installation, common CLI commands, Dockerfiles, and core container workflows.

This Docker Basics Cheatsheet provides a quick reference for essential Docker commands and configuration patterns. Perfect for developers getting started with containerization.

🐳 Docker Basics

Install Docker for your OS.
Shows the client and server versions of Docker installed.

docker version

Displays system-wide information such as number of containers, images, storage driver, etc.

docker info

Lists all available Docker commands and options. Use docker <command> --help for detailed help on any specific command.

docker help

🛠️ Dockerfile Basics

A Dockerfile defines how to build a custom Docker image. Below is a simple example:

# Use an official Node.js image
FROM node:20-alpine

# Set the working directory inside the container
WORKDIR /app

# Copy package.json and install dependencies
COPY package*.json ./
RUN npm install

# Copy the rest of your application code
COPY . .

# Define the default command to run
ENTRYPOINT ["npm", "start"]

To build an image from this Dockerfile:

docker build -t my-node-app .

📦 Images

Downloads a Docker image from a remote registry (usually Docker Hub) to your local machine.
- Example: docker pull ubuntu:20.04

docker pull <image-name>

Builds a Docker image from a Dockerfile in the current directory. The -t option tags the image with a name.
- Example: docker build -t myapp .

docker build -t <image-name> .

Lists all images stored locally on your machine, including their IDs, sizes, and creation dates.

docker images

Removes a specific image from your local machine.

docker rmi <image-id or name>

💡 Tip: Use docker rmi -f to force-remove an image even if it's in use.

📦 Containers

Creates and starts a new container from the specified image.
- Example: docker run nginx

docker run <image-name>

Starts a container in interactive mode with a TTY, allowing shell access.
- Example: docker run -it ubuntu bash

docker run -it <image> bash

Shows currently running containers with details like container ID, image, command, and uptime.

docker ps

Lists all containers, including those that have exited.

docker ps -a

Stops a running container gracefully (sends SIGTERM).

docker stop <container-id>

Starts a stopped container without creating a new one.

docker start <container-id>

Stops and then restarts a container.

docker restart <container-id>

Deletes a stopped container permanently.

docker rm <container-id>

🧰 Container Management

Runs a command inside a running container, often used to open an interactive shell.
- Example: docker exec -it mycontainer bash

docker exec -it <container-id> <command>

Fetches and displays logs from a container’s stdout and stderr.

docker logs <container-id>

Outputs low-level JSON data about a container or image (network config, mount points, etc).

docker inspect <container-id>

Shows the active processes running inside a container.

docker top <container-id>

Copies files from container to local:

docker cp <container-id>:<path-in-container> <local-path>

Copies files from local to container:

docker cp <local-path> <container-id>:<path-in-container>

Displays live stream of container resource usage (CPU, memory, I/O).

docker stats

📁 Volumes

Creates a new Docker-managed volume.

docker volume create <volume-name>

Lists all Docker volumes on your system.

docker volume ls

Removes a specific volume.

docker volume rm <volume-name>

🌐 Networks

Lists all Docker networks (bridge, host, custom, etc.).

docker network ls

Creates a custom Docker network, useful for inter-container communication.

docker network create <network-name>

Deletes a custom Docker network.

docker network rm <network-name>

Shows configuration and connected containers for the specified network.

docker network inspect <network-name>

🧹 Clean-Up and Pruning

Cleans up all unused containers, networks, dangling images, and optionally volumes.

docker system prune

Removes unused images that are not associated with any container.

docker image prune

Removes all stopped containers.

docker container prune

Deletes unused volumes.

docker volume prune