Docker-compose, installed with Snap, gives error on YML file

I've installed docker with Snap Package Manager. It says it has the latest version, but docker-compose gives error about the syntax which looks like it's not the latest version.

Example docker-compose.yml

version: '3.9'

services:

  documentation:
    image: nginx:latest
    container_name: docs
    volumes:
      - ./site:/var/www/html
      - ./etc/nginx/nginx.conf:/etc/nginx/nginx.conf:ro
      - ./var/log/nginx:/var/log/nginx
    networks:
      my-net:
        ipv4_address: 172.30.0.110

networks:
  my-net:
    external: true
    name: my-net

On DigitalOcean

$ docker-compose --version
docker-compose version 1.27.4, build 40524192

And the docker-compose config command looks good.

On my Ubuntu with Docker in Snap

cops@emdev01:~/cops/documentation$ docker-compose --version
docker-compose version 1.25.5, build unknown

And the docker-compose config command gives the following output:

$ docker-compose config
ERROR: Version in "./docker-compose.yml" is unsupported. 
You might be seeing this error because you're using the wrong Compose file version. 
Either specify a supported version (e.g "2.2" or "3.3") and place your service definitions 
under the `services` key, or omit the `version` key and place your service definitions at the 
root of the file to use version 1.

For more on the Compose file format versions, see https://docs.docker.com/compose/compose-file/

The docker-compose used:

$ which docker-compose
/snap/bin/docker-compose

And the info shows the following:

$ sudo snap info docker
name:      docker
summary:   Docker container runtime
publisher: Canonical✓
store-url: https://snapcraft.io/docker
contact:   https://github.com/docker-snap/docker-snap/issues?q=
license:   (Apache-2.0 AND MIT AND GPL-2.0)
description: |

[SNIP]

services:
  docker.dockerd: simple, enabled, active
snap-id:      sLCsFAO8PKM5Z0fAKNszUOX0YASjQfeZ
tracking:     latest/stable
refresh-date: today at 09:46 UTC
channels:
  latest/stable:    20.10.8      2021-08-27 (1125) 122MB -
  latest/candidate: 20.10.8      2021-09-29 (1234) 121MB -
  latest/beta:      20.10.9      2021-10-08 (1310) 122MB -
  latest/edge:      20.10.9      2021-11-09 (1399) 122MB -
  17.03/stable:     17.03.2-ce-1 2017-07-20  (159)  42MB -
  17.03/candidate:  17.03.2-ce-1 2017-06-30  (159)  42MB -
  17.03/beta:       ↑
  17.03/edge:       17.03.2-ce-1 2017-06-30  (159)  42MB -
installed:          20.10.8                 (1125) 122MB -
adminlinux@emdev01:~$

So, the above look like I'm using the latest Docker which is installed with Snap.

Then why do I get the error on the docker-compose file?

Fixed it by uninstalling the Snap version of Docker and installing Docker the old-fashioned way with apt.

The reason is that Snap does some weird things. @muru told me that docker-compose is no part of the Snap Package. But there is a /snap/bin/docker-compose. That one is an old version, and there is no Snap Package for Docker-Compose, let alone one of the more recent dates.

Therefore I've removed Docker from Snap and installed Docker again with Apt.

Now everything works as expected.