[BUG] Networking seems broken in 2.40.3

[mschop]

Description

Hi,

I upgraded from 2.40.2 to 2.40.3:

APT-Log:

Upgrade: docker-compose-plugin:amd64 (2.40.2-1~ubuntu.24.04~noble, 2.40.3-1~ubuntu.24.04~noble)

Since the upgrade the networking seems to be completely broken. Services cant reach each other or reach the wrong service.

After downgrading from 2.40.3 to 2.40.2 everything is working again.

I looked through the issues and didn't find any. Does anyone else have the same problem?

Steps To Reproduce

Sorry, I am a little bit unsure about this.

In fact we didn't change our compose setup. Simply the networking seems to go crazy after the release v2.40.3.

1. We start our compose setup (normally working)
2. Services contacting each other contact the wrong services or cannot contact the other service at all.

Compose Version

$ docker compose version
Docker Compose version v2.40.3

Docker Environment

$ docker info
Client: Docker Engine - Community
 Version:    28.5.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.29.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.40.3
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 32
  Running: 31
  Paused: 0
  Stopped: 1
 Images: 78
 Server Version: 28.5.1
 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
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: b98a3aace656320842a23f4a392a33f46af97866
 runc version: v1.3.0-0-g4ca628d1
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.14.0-114036-tuxedo
 Operating System: Ubuntu 24.04.3 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 32
 Total Memory: 62.5GiB
 Name: -----
 ID: 83acb5da-2c02-4489-9042-4fecaefc1089
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

No response

[ndeloof]

Without a reproductible example I hardly can help here.
Can you inspect container and network being created by Compose 2.40.3 and compare with earlier version ?

[mschop]

I am just trying to figure out more details and prepare an example. I'll come back to you.

FYI: Maybe this is related to #13346 because we also have a lot of extends and depends_on in our code.