'extra_hosts' not working anymore in 'docker stack deploy'

[membersound]

Description

So far, it was possible to pass docker compose config output to docker stack deploy without problems.

Today I upgraded to docker 25.0.2, and discovered loss of the extra_hosts mapping. The tag is completely ignored with the command, and nothing is written to /etc/hosts anymore!

This might be related to:
compose-spec/compose-spec#156
docker/buildx#2201

Steps To Reproduce

cat docker-compose.yml

version: '3.8'

services:
  app:
    image: httpd:2.4
    extra_hosts:
      - "host.docker.internal:host-gateway"

Run:

docker compose config | (sed '/^name:/d') | docker stack deploy -c - httpd

Compose Version

Docker Compose version v2.24.5

Docker Environment

Client: Docker Engine - Community
 Version:    25.0.2
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.12.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.24.5
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 1
  Running: 1
  Paused: 0
  Stopped: 0
 Images: 10
 Server Version: 25.0.2
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  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 splunk syslog
 Swarm: active
  NodeID: j9wtq70drkn7uz09ve5cx7iru
  Is Manager: true
  ClusterID: 3kmynxgzfqluz4h5wv46zpu4j
  Managers: 1
  Nodes: 1
  Default Address Pool: 10.0.0.0/8  
  SubnetSize: 24
  Data Path Port: 4789
  Orchestration:
   Task History Retention Limit: 5
  Raft:
   Snapshot Interval: 10000
   Number of Old Snapshots to Retain: 0
   Heartbeat Tick: 1
   Election Tick: 10
  Dispatcher:
   Heartbeat Period: 5 seconds
  CA Configuration:
   Expiry Duration: 3 months
   Force Rotate: 0
  Autolock Managers: false
  Root Rotation In Progress: false
  Node Address: 127.0.0.1
  Manager Addresses:
   127.0.0.1:2377
 Runtimes: runc io.containerd.runc.v2
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc version: v1.1.12-0-g51d5e94
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.2.0-39-generic
 Operating System: Ubuntu 23.04
 OSType: linux
 Architecture: x86_64
 CPUs: 16
 Total Memory: 62GiB
 Name: 
 ID: 
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Username: 
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

No response

[ndeloof]

I guess the root cause is the adoption of = as canonical separator as host=IP, see compose-spec/compose-go#499

We are not in charge for the docker stack command, please report this issue to docker/cli