How to specify Memory & CPU limit in docker compose version 3

Question

I am unable to specify CPU and memory limitation for services specified in version 3.

With version 2 it works fine with mem_limit & cpu_shares parameters under the services. But it fails while using version 3, putting them under deploy section doesn't seem worthy unless I am using swarm mode.

Can somebody help?

    version: "3"
    services:
      node:
        build:
         context: .
          dockerfile: ./docker-build/Dockerfile.node
        restart: always
        environment:
          - VIRTUAL_HOST=localhost
        volumes:
          - logs:/app/out/
        expose:
          - 8083
        command: ["npm","start"]
        cap_drop:
          - NET_ADMIN
          - SYS_ADMIN

Answer 1

I know the topic is a bit old and seems stale, but anyway I was able to use these options:

deploy:
  resources:
    limits:
      cpus: '0.001'
      memory: 50M

when using 3.7 version of docker-compose

What helped in my case, was using this command:

docker-compose --compatibility up

--compatibility flag stands for (taken from the documentation):

If set, Compose will attempt to convert deploy keys in v3 files to their non-Swarm equivalent

Think it's great, that I don't have to revert my docker-compose file back to v2.

Answer 2

deploy:
  resources:
    limits:
      cpus: '0.001'
      memory: 50M
    reservations:
      cpus: '0.0001'
      memory: 20M

More: https://docs.docker.com/compose/compose-file/compose-file-v3/#resources

In you specific case:

version: "3"
services:
  node:
    image: USER/Your-Pre-Built-Image
    environment:
      - VIRTUAL_HOST=localhost
    volumes:
      - logs:/app/out/
    command: ["npm","start"]
    cap_drop:
      - NET_ADMIN
      - SYS_ADMIN
    deploy:
      resources:
        limits:
          cpus: '0.001'
          memory: 50M
        reservations:
          cpus: '0.0001'
          memory: 20M

volumes:
  - logs

networks:
  default:
    driver: overlay

Note:

• Expose is not necessary, it will be exposed per default on your stack network.
• Images have to be pre-built. Build within v3 is not possible
• "Restart" is also deprecated. You can use restart under deploy with on-failure action
• You can use a standalone one node "swarm", v3 most improvements (if not all) are for swarm

Also Note: Networks in Swarm mode do not bridge. If you would like to connect internally only, you have to attach to the network. You can 1) specify an external network within an other compose file, or have to create the network with --attachable parameter (docker network create -d overlay My-Network --attachable) Otherwise you have to publish the port like this:

ports:
  - 80:80

Answer 3

Docker Compose v1 does not support the deploy key. It's only respected when you use your version 3 YAML file in a Docker Stack.

This message is printed when you add the deploy key to you docker-compose.yml file and then run docker-compose up -d

WARNING: Some services (database) use the 'deploy' key, which will be ignored. Compose does not support 'deploy' configuration - use docker stack deploy to deploy to a swarm.

The documentation (https://docs.docker.com/compose/compose-file/#deploy) says:

Specify configuration related to the deployment and running of services. This only takes effect when deploying to a swarm with docker stack deploy, and is ignored by docker-compose up and docker-compose run.

Nevertheless you can use Docker Compose v2. Given the following Docker composition you can use the deploy key to limit your containers resources.

version: "3.9"
services:
  database:
    image: mariadb:10.10.2-jammy
    container_name: mydb
    environment:
      MYSQL_ROOT_PASSWORD: root_secret
      MYSQL_DATABASE: mydb
      MYSQL_USER: myuser
      MYSQL_PASSWORD: secret
      TZ: "Europe/Zurich"
      MARIADB_AUTO_UPGRADE: "true"
    tmpfs:
      - /var/lib/mysql:rw
    ports:
      - "127.0.0.1:3306:3306"
    deploy:
      resources:
        limits:
          cpus: "4.0"
          memory: 200M
    networks:
      - mynetwork

When you run docker compose up -d (Note: in version 2 of Docker Compose you call the docker binary at not the docker-compose python application) and then inspect the resources you see that the memory is limited to 200 MB. The CPU limit is not exposed by docker stats.

❯ docker stats --no-stream
CONTAINER ID   NAME   CPU %     MEM USAGE / LIMIT   MEM %     NET I/O           BLOCK I/O         PIDS
2c71fb8de607   mydb   0.04%     198MiB / 200MiB     99.02%    2.67MB / 3.77MB   70.6MB / 156MB    18

Answer 4

This is possible with version >= 3.8. Here is an example using docker-compose >= 1.28.x :

version: '3.9'

services:
  app:
    image: nginx
    cpus: "0.5"
    mem_reservation: "10M"
    mem_limit: "250M"

Proof of it working (see the MEM USAGE) column :

The expected behavior when reaching memory limit is the container getting killed. In this case, whether set restart: always or adjust your app code.

Limits and restarts settings in Docker compose v3 should now be set using (restart: always is also deprecated):

deploy:
  restart_policy:
    condition: on-failure
    delay: 5s
    max_attempts: 3
    window: 120s
  resources:
    limits:
      cpus: '0.50'
      memory: 50M
    reservations:
      cpus: '0.25'
      memory: 20M

Answer 5

I think there is confusion here over using docker-compose and docker compose (with a space). You can install the compose plugin using https://docs.docker.com/compose/install if you don't already have it.

Here is an example compose file just running Elasticsearch

 version: "3.7"
 services: 
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.15.2
    restart: always
    ports:
      - "9222:9200"
    deploy:
      resources:
        limits:
          cpus: "4"
          memory: "2g"
    environment:
      - "node.name=elasticsearch"
      - "bootstrap.memory_lock=true"
      - "discovery.type=single-node"
      - "xpack.security.enabled=false"
      - "ingest.geoip.downloader.enabled=false"

I have it in a directory called estest the file is called es-compose.yaml. The file sets CPU and memory limits.

If you launch using docker-compose e.g.

docker-compose -f es-compose.yaml up

Then look at docker stats you see

CONTAINER ID   NAME                     CPU %     MEM USAGE / LIMIT     MEM %     NET I/O           BLOCK I/O        PIDS
e3b6253ee730   estest_elasticsearch_1   342.13%   32.39GiB / 62.49GiB   51.83%    7.7kB / 0B        27.3MB / 381kB   46

so the cpu and memory resource limits are ignored. During the launch you see the warning

WARNING: Some services (elasticsearch) use the 'deploy' key, which will be ignored. Compose does not support 'deploy' configuration - use `docker stack deploy` to deploy to a swarm.

Which I think is what leads people to look at Docker stack/swarm. However if you just switch to using the newer docker compose now built in to the docker CLI https://docs.docker.com/engine/reference/commandline/compose/ e.g.

docker compose -f es-compose.yaml up

And look again at docker stats you see

CONTAINER ID   NAME                     CPU %     MEM USAGE / LIMIT     MEM %     NET I/O           BLOCK I/O        PIDS
d062eda10ffe   estest-elasticsearch-1   0.41%     1.383GiB / 2GiB       69.17%    8.6kB / 0B        369MB / 44MB     6

Therefore the limits have been applied.

This is better in my opinion than swarm as it still allows you to build containers as part of the compose project and pass environment easily via a file. I would recommend removing docker-compose and switching over to use the newer docker compose wherever possible.

Answer 6

I have other experiences, maybe somebody can explain this.

Maybe this is bug(i think this is a feature), but, I am able to use deployments limits (memory limits) in docker-compose without swarm, hovever CPU limits doesn't work but replication does.

$> docker-compose --version
docker-compose version 1.29.2
$> docker  --version
Docker version 20.10.12

version: '3.2'

services:
  limits-test:
    image: alexeiled/stress-ng
    command: [
     '--vm', '1', '--vm-bytes', '20%', '--vm-method', 'all', '--verify', '-t', ' 10m', '-v'

    ]
    deploy:
      resources:
        limits:
          cpus: '0.50'
          memory: 1024M

Docker stats

b647e0dad247   dc-limits_limits-test_1   0.01%     547.1MiB / 1GiB     53.43%    942B / 0B   0B / 0B     3

Edited, thx @Jimmix