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/