version: "3.8"

services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
    deploy:
      # Service mode: use "replicated" for a set number of replicas,
      # or "global" to run one instance on every node.
      mode: replicated

      # Number of container replicas to run (only applicable in replicated mode)
      replicas: 3

      # Rolling update configuration (applies when updating the service)
      update_config:
        # Number of containers to update at the same time
        parallelism: 2
        # Delay between updating groups of containers (e.g., "10s" for 10 seconds)
        delay: 10s
        # Action to take if an update fails: rollback, pause, or continue
        failure_action: rollback
        # Time to monitor each updated container before proceeding to the next batch
        monitor: 10s
        # Maximum failure ratio (0.0 to 1.0) acceptable during the update
        max_failure_ratio: 0.3

      # Rollback configuration (applies if a deployment needs to be undone)
      rollback_config:
        parallelism: 1
        delay: 10s
        # Action to take if rollback fails
        failure_action: pause
        monitor: 10s
        max_failure_ratio: 0.2

      # Restart policy for containers in the service
      restart_policy:
        # Restart condition can be "none", "on-failure", or "any"
        condition: on-failure
        # Delay between restart attempts
        delay: 5s
        # Maximum number of restart attempts before considering the container as failed
        max_attempts: 3
        # Time window used to evaluate restart attempts (e.g., "120s")
        window: 120s

      # Resource constraints and reservations for containers
      resources:
        limits:
          # Maximum number of CPUs the container can use (as a fraction or whole number)
          cpus: "0.50"
          # Maximum memory (e.g., "50M" for 50 megabytes)
          memory: 50M
        reservations:
          # Guaranteed minimum CPUs for the container
          cpus: "0.25"
          # Guaranteed minimum memory
          memory: 20M

      # Placement constraints and preferences to control which nodes run the service
      placement:
        # Constraints ensure that only nodes meeting certain conditions are eligible.
        constraints:
          - node.role == manager
          - node.labels.region == us-east
        # Preferences allow you to influence (but not enforce) distribution.
        preferences:
          - spread: node.labels.az

      # Custom metadata labels for the service
      labels:
        com.example.description: "Sample web service using all deploy parameters"