Feature: add the --builder flag support for build parameter for multi-arch builds

[HarvyNBB]

Description

• Brief:
  Reference to the documentation
  Since it's possible to support multi-arch builds in docker-compose.yml,

Additionally reference to the documentation

In newer versions of Docker Desktop and Docker Engine, you’re using Buildx by default when you invoke the docker build command.

as a result, if the buildkit is enabled on the docker engine, then I assume docker compose build would use buildx

So during building simultaneous services with multi-arch there is a buildkit issue | buildx issue faced while trying to build multi arch builds for multiple services

Note: I'm not sure whether this is buildx issue or buildkit issue, so I created an issue for both

so in order to get over this issue it would be so beneficial for multi-arch builds if the builder could be either passed via a flag or defined in the docker-compose.yml
for e.g docker-compose.yml

Multiple services:

version: '3.7'

services:
 
  service_1:
    container_name: service_1-${VERSION}
    image: service_1:${VERSION}    
    build:
      context: .
      dockerfile: Dockerfile
      builder: test1
      platforms: 
        - ${PLATFORM_1}
        - ${PLATFORM_2}
  
  service_2:
    container_name: service_2-${VERSION}
    image: service_2:${VERSION}
    build:
      context: .
      dockerfile: Dockerfile
      builder: test2
      platforms: 
        - ${PLATFORM_1}
        - ${PLATFORM_2}

  service_3:
    container_name: service_3-${VERSION}
    image: service_3:${VERSION}
    build:
      context: .
      dockerfile: Dockerfile
      builder: test3
      platforms: 
        - ${PLATFORM_1}
        - ${PLATFORM_2}

commands to run

docker buildx create --name test1
docker buildx create --name test2
docker buildx create --name test3
docker compose build service_1 service_2 service_3 

Or for a single service

version: '3.7'

services:
 
  service_1:
    container_name: service_1-${VERSION}
    image: service_1:${VERSION}    
    build:
      context: .
      dockerfile: Dockerfile
      platforms: 
        - ${PLATFORM_1}
        - ${PLATFORM_2}

docker buildx create --name test1
docker compose build --builder test1 service_1 

[ndeloof]

We could indeed introduce builder, as a follow-up for compose-spec/compose-spec#233

[milas]

Compose v2.20.0+ respects the BUILDX_BUILDER env var and also supports build --builder=my-builder.

Note that other commands that (might) perform builds like up and run do not support the --builder flag currently.