Networking

# List networks
docker network ls

# List networks with more details
docker network ls --format "table {{.ID}}\t{{.Name}}\t{{.Driver}}\t{{.Scope}}"

# Create a network
docker network create my-network

# Create a network with specific driver
docker network create --driver overlay my-swarm-network

# Connect container to network
docker network connect my-network container-name

# Connect with static IP address
docker network connect --ip 172.18.0.10 my-network container-name

# Disconnect container from network
docker network disconnect my-network container-name

# Inspect network
docker network inspect my-network

# Inspect specific details with format
docker network inspect -f '{{range .Containers}}{{.Name}} {{.IPv4Address}}{{end}}' my-network

# Remove network
docker network rm my-network

# Remove all unused networks
docker network prune

# Filter networks by criteria
docker network ls --filter driver=bridge

# Create a container with a specific network
docker run --network=my-network -d nginx

# Create a bridge network with custom subnet
docker network create --driver bridge \
  --subnet=172.18.0.0/16 \
  --gateway=172.18.0.1 \
  my-custom-network

# Create a network with IP address range
docker network create --driver bridge \
  --subnet=172.20.0.0/16 \
  --ip-range=172.20.5.0/24 \
  --gateway=172.20.0.1 \
  my-range-network

# Create an overlay network with encryption
docker network create --driver overlay \
  --opt encrypted=true \
  --attachable \
  secure-overlay-network

# Create a macvlan network
docker network create --driver macvlan \
  --subnet=192.168.1.0/24 \
  --gateway=192.168.1.1 \
  -o parent=eth0 \
  macvlan-network

# Start container with network
docker run -d --network my-network --name container1 nginx

# Start another container in same network
docker run -d --network my-network --name container2 nginx

# Connect running container to additional network
docker network connect my-second-network container1

# Create container with static IP
docker run -d --network my-network --ip 172.18.0.10 --name fixed-ip-container nginx

# Connect container to multiple networks during creation
docker run -d --network my-network --network my-second-network --name multi-network-container nginx

# Test communication between containers
docker exec container1 ping container2

# Inspect container's network settings
docker inspect --format='{{json .NetworkSettings.Networks}}' container1

# docker-compose.yml example with custom networks
version: '3.8'
services:
  web:
    image: nginx
    networks:
      - frontend
  api:
    image: my-api:latest
    networks:
      - frontend
      - backend
  db:
    image: postgres:13
    networks:
      - backend

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge
    internal: true  # No internet access for enhanced security

# Example of service discovery in Swarm
docker service create --name db --network app-network postgres
docker service create --name api --network app-network --env DB_HOST=db my-api

# Set custom DNS servers
docker run --dns 8.8.8.8 --dns 8.8.4.4 nginx

# Set DNS search domains
docker run --dns-search example.com nginx

# Set DNS options
docker run --dns-opt timeout:3 nginx

# Check container networking
docker inspect container-name

# View network-specific information
docker inspect -f '{{json .NetworkSettings.Networks}}' container-name | jq

# View container logs
docker logs container-name

# Check container network connectivity
docker exec container-name ping other-container

# Test DNS resolution within container
docker exec container-name nslookup other-service

# Check if ports are actually listening
docker exec container-name netstat -tulpn

# Install network troubleshooting tools in container
docker exec container-name sh -c "apt-get update && apt-get install -y iputils-ping net-tools curl dnsutils"

# Check container's routing table
docker exec container-name route -n

# Verify port mappings
docker port container-name

# View all container IPs
docker inspect --format='{{.Name}} - {{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' $(docker ps -q)

# Check network interface configuration inside container
docker exec container-name ip addr show

# Debug overlay network
docker network inspect -v overlay-network-name

# Capture network traffic
docker run --net=container:target-container nicolaka/netshoot tcpdump -i eth0

# Check Docker DNS configuration
docker exec container-name cat /etc/resolv.conf