Resource Requirements

• docker run has many options, service create has different options
• Set at service create/update, but are controlled per-container
• Set for CPU and memory, reserving and limiting
• Maximum given to container
  • --limit-cpu .5
  • --limit-memory 256M
• Beware of OOME (with or without limits)
  • when memory resource limit is hit, container will be killed and rescheduled
• Minimum free needed to schedule container (Swarm keeps track)
  • --reserve-cpu .5
  • --reserve-memory 256M

Examples

• Reserve cpu and memory
  • docker service create --reserve-memory 800M --reserve-cpu 1 mysql
• Limit cpu and memory
  • docker service create --limit-memory 150M --limit-cpu .25 nginx
• Service update is the same
• Remove them with update to 0
  • docker service update --limit-memory 0 --limit-cpu 0 myservice

Resource Requirements in Stack Files

version: "3.1"
services:
  database:
    image: mysql
    deploy:
      resources:
        limits:
          cpus: '1'
          memory: 1G
        reservations:
          cpus: '0.5'
          memory: 500M

External links

• https://docs.docker.com/config/containers/resource\_constraints/