I spent last weekend diving deep into Docker and came out the other side with a solid understanding of its fundamentals. To cement what I learned, I created this command cheat sheet. It's aimed at helping you (and future me!) work confidently with Docker day-to-day.

🐳 Checking Docker Version

docker -v

🔍 Inspecting Containers

List running containers:

docker ps
# or
docker container ls

List all containers (running + stopped):

docker container ls -a

• a or -all: Show all containers, not just running ones.

🗑️ Removing Containers and Images

Remove a container:

docker rm <container_name>

List all images:

docker images

Remove an image:

docker rmi <image_name>

• rmi: Remove one or more images by name or ID.

🏗️ Creating and Running Containers

Run a container interactively:

docker run -it <image_name>

• i: Keep STDIN open.

• t: Allocate a pseudo-TTY (interactive shell).

Run in background (detached mode):

docker run -it -d <image_name>

• d: Detached mode. Runs in background.

Run with a specific name:

docker run --name my-container -it <image_name>

• -name: Assign a custom name to the container.

📥 Pulling Docker Images

docker pull <image_name>

▶️ Start and Stop Containers

Start an existing container:

docker start <container_name>

Stop or kill a container:

docker stop <container_name>
docker kill <container_name>

• stop: Graceful shutdown.

• kill: Immediate termination.

🛠️ Running Commands in Containers

Execute a one-off command:

docker exec <container_name> <command>
# Example:
docker exec my-container ls

Start an interactive shell:

docker exec -it <container_name> /bin/bash

Exit container but keep it running:

CTRL/CMD + D

🧱 Building Images

docker build -t <image_name> <path>

• t: Tags the image with a name.

• <path>: Typically . to refer to the current directory.

docker build -t my-server .

🌐 Port Mapping

docker run --name <name> -p <host_port>:<container_port> <image_name>

• p: Maps ports from container to host.

• Example:

docker run --name mongo-service -p 27017:27017 mongo

Update port mapping for an existing container:

docker container update --publish-add 8080:80 <container_name>

🌱 Environment Variables

docker run -e KEY=VALUE <image_name>

docker run -e ENV=production -e DB_URL=mongodb://localhost my-app

📦 Docker Volumes

Create a volume:

docker volume create my-volume

List all volumes:

docker volume ls

Mount a volume to a container:

docker run -v my-volume:/data/db mongo

• v: Mounts a volume.

• /data/db: Where MongoDB stores its data internally.

🔗 Docker Networks

Create a custom network:

docker network create my-network

List networks:

docker network ls

Types of Docker networks:

• bridge: Default. Isolated internal network on the host.

• host: Shares host's networking directly.

Run a container on a specific network:

docker run --name my-app --network my-network -p 3000:3000 my-image

🚀 Push Custom Images to Docker Hub

Step-by-step:

1. Create a repo on hub.docker.com (e.g., myusername/myimage)

2. Tag the image locally:

docker build -t myusername/myimage .

1. Log in:

docker login

1. Push:

docker push myusername/myimage

🧩 Docker Compose

Example docker-compose.yaml

services:
  mongodb:
    image: "mongo"
    container_name: mongodb
    ports:
      - "27017:27017"
    volumes:
      - mongodb_data:/data/db

  backend:
    build: .
    container_name: backend_app
    depends_on:
      - mongodb
    ports:
      - "3000:3000"
    environment:
      MONGO_URL: "mongodb://mongodb:27017"

volumes:
  mongodb_data:

Run the compose setup:

docker-compose up

Tear down everything:

docker-compose down --volumes