How to fix Bind for 0.0.0.0:3000 failed: port is already allocated in Docker

# On Linux using lsof
sudo lsof -i :3000

# Using netstat
sudo netstat -tulpn | grep :3000

# Using ss (modern replacement for netstat)
sudo ss -tulpn | grep :3000

# On macOS
lsof -nP -iTCP:3000 | grep LISTEN

# List running containers with their ports
docker ps --format "table {{.Names}}\t{{.Ports}}"

# Stop a specific container
docker stop <container_name>

# Or stop all containers from another compose project
cd /path/to/other/project
docker-compose down

# Stop and remove all containers from this project
docker-compose down

# Find the PID from lsof output
sudo lsof -i :3000

# Kill the process
kill <PID>

# Force kill if needed
kill -9 <PID>

# Or if it's a system service
sudo systemctl stop nginx
sudo systemctl stop apache2

services:
  web:
    image: myapp
    ports:
      - "3001:3000"  # Changed host port from 3000 to 3001

# Remove all stopped containers
docker container prune

# Or remove containers from a specific project
docker-compose down --remove-orphans

# Force remove all containers for this project
docker-compose rm -f

# Nuclear option: remove ALL stopped containers
docker rm $(docker ps -aq)

# Linux
sudo systemctl restart docker

# macOS (Docker Desktop)
# Click the Docker icon in the menu bar > Restart

# Or from the command line
killall Docker && open /Applications/Docker.app

# Windows (Docker Desktop)
# Right-click Docker icon in system tray > Restart

# WRONG: Two services using the same host port
services:
  web:
    ports:
      - "3000:3000"
  api:
    ports:
      - "3000:8080"  # Conflict! Same host port 3000

# CORRECT: Unique host ports
services:
  web:
    ports:
      - "3000:3000"
  api:
    ports:
      - "3001:8080"  # Different host port

# These conflict (tcp is the default):
ports:
  - "8080:8080"
  - "8080:8080/tcp"