[BUG] Resources reservations has no effect in v3 for non swarm

[FireEmerald]

Description

This issue belongs to the NON SWARM mode.

As per current definition the deploy section of the v3 compose file shall only have a effect when using swarm, expect for resources:

The following sub-options only takes effect when deploying to a swarm with docker stack deploy, and is ignored by docker-compose up and docker-compose run, except for resources.

Which works for setting deploy: resources: limits: memory: 100M, even when not in swarm mode nor using the --compatibility flag. The inspect command shows correct "Memory": 104857600.

BUT which does not work is setting deploy: resources: reservations: memory: 100M - it has no effect. Looked up via docker inspect containerA shows:

[
  {
    "HostConfig": {
      "MemoryReservation": 0,
  }
]

What does work is setting mem_reservation on the service level but the official Compose Specification says about:

mem_reservation DEPRECATED: use deploy.reservations.memory.

Steps To Reproduce

See description to reproduce.

Compose Version

Docker Compose version v2.12.2

Docker Environment

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Docker Buildx (Docker Inc., v0.9.1-docker)
  compose: Docker Compose (Docker Inc., v2.12.2)
  scan: Docker Scan (Docker Inc., v0.21.0)

Server:
 Containers: 3
  Running: 1
  Paused: 0
  Stopped: 2
 Images: 4
 Server Version: 20.10.21
 Storage Driver: btrfs
  Build Version: Btrfs v5.10.1
  Library Version: 102
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 770bd0108c32f3fb5c73ae1264f7e503fe7b2661
 runc version: v1.1.4-0-g5fd4c4d
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: default
  cgroupns
 Kernel Version: 5.10.0-15-cloud-amd64
 Operating System: Debian GNU/Linux 11 (bullseye)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 7.773GiB
 Name: monitoringlinux-dev
 ID: TQFM:TIMQ:XNFZ:MMPO:J2BM:6XG4:56KA:CFBA:MTD7:H3BI:G65U:6IXL
 Docker Root Dir: /opt/docker-data
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

No response

[laurazard]

Hi @FireEmerald, thanks for your report.

This was fixed in #9947, which was included in Compose versionv2.13.0.

Using that (or a later version) it works as expected. With the Compose file:

services:
  a:
    image: alpine
    command: top
    deploy:
      resources:
        reservations:
          memory: 100M

and then running docker inspect <container_name> I see:

[...]
"MemoryReservation": 104857600,
[...]

Please download a newer version of Compose, or update Docker Desktop to get a newer version to get this working.