Variables pulled when using an env_file override, now override environment settings in docker-compose.yml

[lingmann]

Description

With Docker Compose V2, variables pulled in via an env_file override, now override environment variables specified in docker-compose.yml.

Steps to reproduce the issue:

Test Files

$ cat docker-compose.yml
version: '2.4'
services:
  test:
    image: alpine
    environment:
      PGHOST: sql

$ cat docker-compose.override.yml
version: '2.4'
services:
  test:
    env_file:
      - .env

$ cat .env
PGHOST=localhost

Describe the results you received:

When using Docker Compose V2, PGHOST is set to localhost from the .env file and ignores the value specified in the docker-compose.yml environment.

$ docker compose version
Docker Compose version v2.2.1

$ docker compose -f docker-compose.yml -f docker-compose.override.yml config
services:
  test:
    environment:
      PGHOST: localhost
    env_file:
    - .env
    image: alpine
    networks:
      default: null
networks:
  default:
    name: test_default

Describe the results you expected:

PGHOST should be set to sql similar to behavior with Docker Compose V1

$ docker-compose -v
docker-compose version 1.29.2, build 5becea4c

$ docker-compose -f docker-compose.yml -f docker-compose.override.yml config
services:
  test:
    environment:
      PGHOST: sql
    image: alpine
version: '2.4'

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker compose version:

Docker Compose version v2.2.1

Output of docker info:

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc., v0.7.1)
  compose: Docker Compose (Docker Inc., v2.2.1)
  scan: Docker Scan (Docker Inc., v0.14.0)

Server:
 Containers: 4
  Running: 1
  Paused: 0
  Stopped: 3
 Images: 4
 Server Version: 20.10.11
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 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: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7b11cfaabd73bb80907dd23182b9347b4245eb5d
 runc version: v1.0.2-0-g52b36a2
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
  cgroupns
 Kernel Version: 5.10.76-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 15.64GiB
 Name: docker-desktop
 ID: 4CIP:X5EB:G7AH:O4KV:SDBN:SBWT:H4HH:76CX:I5JX:3HOO:RZY4:KYQK
 Docker Root Dir: /var/lib/docker
 Debug Mode: true
  File Descriptors: 43
  Goroutines: 45
  System Time: 2022-01-04T03:48:54.665447375Z
  EventsListeners: 3
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: true
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically closed because it had not recent activity during the stale period.

[stale[bot]]

This issue has been automatically closed because it had not recent activity during the stale period.