buildx bake always sets COMPOSE_PROJECT_NAME to "bake"

Contributing guidelines

[X] I've read the contributing guidelines and wholeheartedly agree

I've found a bug and checked that ...

[X] ... the documentation does not mention anything about my problem
[X] ... there are no open or closed issues that are related to my problem

Description

buildx bake does not honor COMPOSE_PROJECT_NAME from environment variable or any .env file. This behavior changed from version 14 where the variable was set correctly.

Expected behaviour

Content of COMPOSE_PROJECT_NAME can be overridden with an environment variable.

Actual behaviour

COMPOSE_PROJECT_NAME is always set to "bake".

Buildx version

github.com/docker/buildx v0.15.1 1c1dbb2e4cb5363110f42102744a08d034c2300d

Docker info

Client:
 Version:    27.0.3
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.15.1
    Path:     /usr/local/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.28.1
    Path:     /usr/local/libexec/docker/cli-plugins/docker-compose

Builders list

NAME/NODE   DRIVER/ENDPOINT   STATUS    BUILDKIT   PLATFORMS
default*                      error

Configuration

# .env
COMPOSE_PROJECT_NAME=anything

# docker-compose.yml
services:
    php-fpm:
        image: 'php-fpm:latest'
        build:
            context: .
            dockerfile: './builds/Dockerfile'
            args:
                COMPOSE_PROJECT_NAME: ${COMPOSE_PROJECT_NAME}

docker buildx bake --print
# or
COMPOSE_PROJECT_NAME=something docker buildx bake --print

Build logs

[+] Building 0.0s (1/1) FINISHED
 => [internal] load local bake definitions                                                                                                                                                                                                   0.0s
 => => reading docker-compose.yml 219B / 219B                                                                                                                                                                                                0.0s
{
  "group": {
    "default": {
      "targets": [
        "php-fpm"
      ]
    }
  },
  "target": {
    "php-fpm": {
      "context": ".",
      "dockerfile": "./builds/Dockerfile",
      "args": {
        "COMPOSE_PROJECT_NAME": "bake"
      },
      "tags": [
        "php-fpm:latest"
      ]
    }
  }
}

Additional info

No response

docker / buildx

buildx bake always sets COMPOSE_PROJECT_NAME to "bake" #2573