[BUG] !reset is not correctly handled when used with extends and templates

[elgarfo]

Description

issue: using a template file which references its own services and uses !reset does not actually reset the value.

i tested all compose versions between 2.24.3 and 2.28.1.

• v2.24.3 is the last version i saw this working as expected.
• 2.24.4 and 2.24.5 fail to render the config with "Circular reference error"
• 2.24.6+ do not reset the value

all of the tested versions actually do reset the value, when only rendering the template (i.e. ./docker-compose -f compose.base.yml config)

compose.base.yml

services:
  init:
    image: alpine:latest
    command: "sleep infinity"
  test:
    extends: { service: init }
    command: !reset

compose.yml

services:
  init:
    extends:
      file: compose.base.yml
      service: init
  test:
    extends:
      file: compose.base.yml
      service: test

expectation: running docker-compose config, "!reset" is evaluated and the resulting service "test" does not have a command configured.

---

expected result (and 2.24.3 actually produces this):

name: test
services:
  init:
    command:
      - sleep
      - infinity
    image: alpine:latest
    networks:
      default: null
  test:
    image: alpine:latest
    networks:
      default: null
networks:
  default:
    name: test_default

---

(note: 2.24.7 outputs different, but behaves the same)
actual result (which is produced by 2.24.6+):

name: test
services:
  init:
    command:
      - sleep
      - infinity
    image: alpine:latest
    networks:
      default: null
  test:
    command:
      - sleep
      - infinity
    image: alpine:latest
    networks:
      default: null
networks:
  default:
    name: test_default

as can be observed: the command value for "test" service is not reset.

---

the only workaround i found, was to specify "!reset" directly in compose.yml. but this limits reusability of already working configurations. and it actually breaks things when updating from 2.24.3.

also worth a mention: this is not happening when using compose.override.yml. meaning: if compose.base.yml is renamed to compose.yml and the overrides (which i did leave out in the example files above) are moved to compose.override.yml (dropping the "extends") the command is also correctly reset.

Steps To Reproduce

1. create compose.base.yml file
2. create compose.yml file
3. run docker-compose config

Compose Version

2.24.3
Docker Compose version v2.24.3
2.24.4
Docker Compose version v2.24.4
2.24.5
Docker Compose version v2.24.5
2.24.6
Docker Compose version v2.24.6
2.24.7
Docker Compose version v2.24.7
2.25.0
Docker Compose version v2.25.0
2.26.0
Docker Compose version v2.26.0
2.26.1
Docker Compose version v2.26.1
2.27.0
Docker Compose version v2.27.0
2.27.1
Docker Compose version v2.27.1
2.27.2
Docker Compose version v2.27.2
2.27.3
Docker Compose version v2.27.3
2.28.0
Docker Compose version v2.28.0
2.28.1
Docker Compose version v2.28.1

Docker Environment

Client: Docker Engine - Community
 Version:    26.0.0
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.13.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.25.0
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 17
  Running: 15
  Paused: 0
  Stopped: 2
 Images: 37
 Server Version: 26.0.0
 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: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc version: v1.1.12-0-g51d5e94
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
 Kernel Version: 5.15.90.1-microsoft-standard-WSL2+
 Operating System: Debian GNU/Linux 11 (bullseye)
 OSType: linux
 Architecture: x86_64
 CPUs: 16
 Total Memory: 29.32GiB
 Name: garfield-work-wsl
 ID: a38a12dd-a1dd-49b2-9707-270e4b6cc023
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No blkio throttle.read_bps_device support
WARNING: No blkio throttle.write_bps_device support
WARNING: No blkio throttle.read_iops_device support
WARNING: No blkio throttle.write_iops_device support

Anything else?

No response

[ndeloof]

Thanks for reporting this, I'll look into this ASAP