[BUG] Can't run compose file with host network

[ParSal123]

Description

I can't use host network in compose services.

Steps To Reproduce

services:
  mysql:
    image: mysql
    networks:
      hostnet: {}

networks:
  hostnet:
    external: true
    name: host

This is my compose file which I copied from the docs (with minor modifications to run). When I do docker compose up I get:

[+] Running 1/1
 ✔ Container project-mysql-1  Created                                                                                                                                                     0.1s 
Attaching to project-mysql-1
Error response from daemon: network-scoped alias is supported only for containers in user defined networks

Compose Version

Docker Compose version 2.20.3

Docker Environment

Client:
 Version:    24.0.5
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  0.11.2
    Path:     /usr/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  2.20.3
    Path:     /usr/lib/docker/cli-plugins/docker-compose
  scan: Docker Scan (Docker Inc.)
    Version:  v0.1.0-280-gc7fa31d4c4
    Path:     /usr/lib/docker/cli-plugins/docker-scan

Server:
 Containers: 3
  Running: 0
  Paused: 0
  Stopped: 3
 Images: 32
 Server Version: 24.0.5
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: true
  Native Overlay Diff: false
  userxattr: false
 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: runc io.containerd.runc.v2
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 091922f03c2762540fd057fba91260237ff86acb.m
 runc version:
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.1.53-1-MANJARO
 Operating System: Manjaro Linux
 OSType: linux
 Architecture: x86_64
 Docker Root Dir: /var/lib/docker
 Debug Mode: true
  File Descriptors: 28
  Goroutines: 59
  System Time: 2023-10-01T16:21:20.898877997+03:30
  EventsListeners: 0
 Experimental: false
 Live Restore Enabled: false

Anything else?

No response

[ndeloof]

host networking is not just a pre-defined network name, it must be enabled using network_mode:

services:
  mysql:
    image: mysql
    network_mode: host

[ElSamhaa]

@ndeloof I think it counts as a bug as the example in the docs doesn't work https://github.com/compose-spec/compose-spec/blob/master/06-networks.md#host-or-none

[ndeloof]

indeed, this has been inherited from the legacy docker compose v1 documentation, by the time it was converted into "compose specification". Better fix the docs then