[BUG] --env-file option is ignored from docker compose --env-file=file.env up

[astrolemonade]

Description

Hey!
docker compose --env-file=file.env up is ignoring the --env-file option.

Steps To Reproduce

1. have a docker-compose.yaml file that should use some environment variables from an environment variables file.
   example:

version: '3.9'
services:
  node:
    image: node:18
    container_name: live_dev
    # it was specifically chosen to hang the container so that we can inspect it
    command: tail -F anything

2. have an file.env file:
   example:

MY_VAR=my_var

3. have the following directory structure:

[~/live_dev] $ tree -a
.
├── docker-compose.yaml
└── file.env

1 directory, 2 files

4. run the docker compose --env-file=file.env up
5. enter the container via docker exec -it live_dev /bin/bash
6. run printenv to see if MY_VAR exists

[~/live_dev] $ docker exec -it live_dev /bin/bash
root@741ec06639ca:/# printenv
HOSTNAME=741ec06639ca
YARN_VERSION=1.22.19
PWD=/
HOME=/root
TERM=xterm
SHLVL=1
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
NODE_VERSION=18.17.0
_=/usr/bin/printenv

7. notice that MY_VAR doesn't exist

Compose Version

Docker Compose version v2.18.1

Docker Environment

Client: Docker Engine - Community
 Version:    24.0.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.11.1
    Path:     /usr/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.18.1
    Path:     /usr/lib/docker/cli-plugins/docker-compose

Server:
 Containers: 4
  Running: 4
  Paused: 0
  Stopped: 0
 Images: 14
 Server Version: 24.0.1
 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 logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 0cae528dd6cb557f7201036e9f43420650207b58
 runc version: 5fd4c4d144137e991c4acebb2146ab1483a97925
 init version: 0b44d36
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.3.12-241.current
 Operating System: Solus 4.4 Harmony
 OSType: linux
 Architecture: x86_64
 CPUs: 12
 Total Memory: 15.5GiB
 Name: catalin
 ID: QGPZ:6HOM:HUOC:EWS6:42UO:UZ47:5PEO:NKUW:VUDH:LQQ7:GI5X:RAY6
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

Adding env_file to the docker-compose.yaml and running docker compose up loads the file and makes the variable present.

version: '3.9'
services:
  node:
    image: node:18
    env_file:
      - file.env
    container_name: live_dev
    # it was specifically chosen to hang the container so that we can inspect it
    command: tail -F anything

Did some investigation and it seems it was removed from build, up and down some time ago(maybe in the Python version and got ported to the Go version, I am not sure). #6800 and also has something to do with #10650
I don't know if this is supposed to happen.

[milas]

The environment variable handling is a bit confusing; there's a lot of backwards compatibility that's resulted in several similar features.

If you want to pass environment variables to a service's container, you have two options:

<svc>.environment

services:
  opt1:
     image: alpine
     command: ["env"]
     environment:
        KEY=value

<svc>.env_file

services:
  opt2:
     image: alpine
     command: ["env"]
     env_file: ["src.env"]

svc.env

KEY=value

---

--env-file

The --env-file command-line argument overrides Compose behavior that automatically looks for a file named .env in the current directory. The .env file (or file at path specified by --env-file) is merged with the system environment to perform variable resolution inside the Compose YAML. That is, this let's you do things like image: ${IMAGE} in your YAML, and then have it substituted by putting IMAGE=alpine in a .env file (or running IMAGE=alpine docker compose ...).

Unfortunately, this is named the same as the env_file YAML field, both of which are taken from Docker CLI's --env-file option, which is confusing, as the YAML field is for passing through to containers, while the CLI flag is for substitution within YAML.

---

I'm closing this issue, but cc @aevesdocker on our docs team, we improved this recently around precedence, syntax & mechanisms, but we might need an extra call-out for this distinction.