What is the difference between Docker Compose and Docker Swarm?

Docker Compose is used for defining and managing multi-container applications within a single host or with a few hosts. It defines services, networks, and volumes in a docker-compose.yml file.

Docker Swarm is a native Docker orchestration system designed for clustering and scaling containers across multiple hosts. Swarm provides fault tolerance, distributed scheduling, and service discovery.

Feature	Docker Compose	Docker Swarm
Purpose	Managing multiple containers on a single host	Container orchestration on a cluster of hosts
Scaling	Limited to one host	Horizontal scaling on a cluster
Fault Tolerance	Not available	Built-in
Distributed Scheduling	Not available	Built-in
Service Discovery	Not available	Built-in
Configuration File	docker-compose.yml	docker stack deploy - uses the same format as docker-compose.yml but for orchestration

Example of a docker-compose.yml file for Compose:

# Docker Compose file
version: '3.8'
services:
  web:
    image: nginx
    ports:
      - "80:80"
  app:
    image: my-app
    depends_on:
      - db
  db:
    image: postgres:13
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password

Example of a stack deployment command in Swarm (uses the same docker-compose.yml file):

# Stack deployment command in Swarm
docker stack deploy -c docker-compose.yml my-stack