Docker limits host resource usage without swarm

Question

I just want to limit the resources of some Docker containers in the docker file. The reason is simple: several applications / services are running on the host. Therefore, I want to avoid that one container can use, for example. all memory that harms other containers.

From the docs I learned, this can be done using resources . But it is above deploy . Therefore, I have to write my file to create docker, as in the following example:

  php: image: php:7-fpm restart: always volumes: - ./www:/www deploy: resources: limits: memory: 512M 

This gave me a warning:

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

And that seems true: docker stats confirms that the container can use all ram from the host.

The documentation says:

Specify the configuration associated with deploying and starting services. This only takes effect when deployed to a swarm with a docker stack deployed and is ignored by docker-compose up and docker-compose.

But I do not need clustering. There seems to be no other way to limit resources using a file-docker-composer. Why is it impossible to specify some kind of memory tag, such as start-parameter in docker run ?

Example: docker run --memory=1g $imageName

This works great for a single container. But I cannot use this (at least without breaking the clean separation of problems), since I need to use two different containers.

Edit: Temp workaround

I found out that I can use mem_limit directly after downgrading from version 3 to version 2 (placing version: '2' on top). But we are currently on version 3.1, so this is not a long solution. And the docs say deploy.resources is a new replacement for v2 tags like mem_limit .

Someday, version 2 is deprecated. So resource management is no longer possible with the latest versions, at least without a swarm? It seems that deterioration for me, can not believe it ...

Answer 1

You can run the docker daemon in swarm mode on one host. This will add additional unnecessary features, such as detecting the etcd service, but all this is behind the scenes.

The Docker documentation contains a “note” here https://docs.docker.com/engine/swarm/swarm-tutorial/#three-networked-host-machines

Answer 2

Since many Docker Compose users complained about this incompatibility of compose v3 vs v2, the team developed a compatibility mode .

You can keep the same deployment structure that you specified, and it won’t be ignored by simply adding the --compatibility flag to the docker-compose (docker-compose --compatibility up) command, as described here . I checked this with version 3.5 and checked the docker statistics and can confirm that this works.