Docker Cheatsheet

Find reference documentation for the Docker platform’s various APIs, CLIs, and file formats

docs.docker.com/reference

Building Images

dockerfile

# Dockerfile
FROM node:24-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev
COPY . .
CMD ["node", "src/index.js"]

bash

# Build an image tagged "myapp:latest"
docker build -t myapp:latest .

# Build with a specific Dockerfile
docker build -f Dockerfile.prod -t myapp:prod .

# Build with build arguments
docker build --build-arg NODE_ENV=production -t myapp:latest .

Use a .dockerignore file to keep images small — at minimum exclude node_modules, .git, and any local config:

.git/
node_modules/

*.log
.env
.envrc

Multi-Stage Builds

Use multi-stage builds to keep production images lean — install dev dependencies in one stage, copy only what you need into the final image:

dockerfile

# Build stage
FROM node:24-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

# Production stage
FROM node:24-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev
COPY --from=build /app/dist ./dist
CMD ["node", "dist/index.js"]

Running Containers

bash

# Run a container in the foreground
docker run myapp:latest

# Run in the background (detached)
docker run -d --name myapp myapp:latest

# Run with port mapping (host:container)
docker run -p 3000:3000 myapp:latest

# Run interactively with a shell
docker run -it myapp:latest sh

# Run a one-off command
docker run --rm myapp:latest node -e "console.log(process.version)"

Flag	Description
`-d`	Run in detached (background) mode
`-p 3000:3000`	Map host port to container port
`--rm`	Remove the container when it exits
`--name`	Assign a name to the container
`-it`	Interactive mode with a TTY (useful for shells)
`-v /host:/container`	Bind mount a host directory into the container
`--platform linux/amd64`	Force a specific platform (useful on Apple Silicon)

Running Node.js Scripts

Run a standalone script without building a full image:

bash

# Run a script from the current directory
docker run --rm -v $PWD:/workspace -w /workspace node:24 node script.js

# Run with npm
docker run --rm -v $PWD:/workspace -w /workspace node:24 npm run dev

# Run an interactive Node REPL
docker run --rm -it node:24 node

For repeated use, define a service in docker-compose.yml instead of typing long docker run commands.

Environment Variables

Inline

bash

# Single variable
docker run -e NODE_ENV=production myapp:latest

# Multiple variables
docker run -e NODE_ENV=production -e LOG_LEVEL=info myapp:latest

From a File

bash

# Load variables from a file
docker run --env-file .env myapp:latest

The env file is a plain list of KEY=VALUE pairs, one per line — no export, no quotes needed:

bash

# .env
NODE_ENV=production
LOG_LEVEL=info
DATABASE_URL=postgres://localhost:5432/mydb

In Compose

yaml

# docker-compose.yml
services:
  app:
    image: myapp:latest
    environment:
      - NODE_ENV=production
      - LOG_LEVEL=info
    env_file:
      - .env

Tagging & Pushing

bash

# Tag an existing image with an additional tag
docker tag myapp:latest registry.example.com/myapp:latest
docker tag myapp:latest registry.example.com/myapp:1.2.3

# Push all tags individually
docker push registry.example.com/myapp:latest
docker push registry.example.com/myapp:1.2.3

Pushing Multiple Tags at Build Time

Use docker buildx to build and push multiple tags in a single command:

bash

docker buildx build \
  --platform linux/amd64 \
  -t registry.example.com/myapp:latest \
  -t registry.example.com/myapp:1.2.3 \
  --push .

Tagging Strategy

A common approach is to tag every image with the Git SHA and conditionally tag with latest or a version number:

bash

GIT_SHA=$(git rev-parse --short HEAD)
docker tag myapp:latest registry.example.com/myapp:$GIT_SHA
docker tag myapp:latest registry.example.com/myapp:latest

Colima (macOS)

Colima is a lightweight alternative to Docker Desktop on macOS. It runs a Linux VM under the hood and exposes the Docker socket so that the standard docker CLI works as normal.

bash

# Install via Homebrew
brew install colima docker

# Start Colima with default settings
colima start

# Start with custom resources
colima start --cpu 4 --memory 8 --disk 60

# Stop the VM
colima stop

# Check status
colima status

After colima start, the docker CLI works exactly as it would with Docker Desktop — no changes to your workflow or scripts.

Apple Silicon

If you need to build or run linux/amd64 images on an Apple Silicon Mac, enable Rosetta emulation:

bash

colima start --arch aarch64 --vm-type vz --vz-rosetta

Or specify the platform per-command:

bash

docker run --platform linux/amd64 myapp:latest

Useful Commands

bash

# List running containers
docker ps

# List all containers (including stopped)
docker ps -a

# Follow container logs
docker logs -f <container>

# Execute a command in a running container
docker exec -it <container> sh

# Remove stopped containers, unused images, and build cache
docker system prune -a