feature: compose config should purge nested x-* tags

[hholst80]

Version

docker-compose version 1.29.2, build 5becea4c
docker-py version: 5.0.0
CPython version: 3.7.10
OpenSSL version: OpenSSL 1.1.0l  10 Sep 2019

Description

docker-compose config should purge nested x-fields

Design idea

input

version: '2'

x-common: &common
  volumes: &common-volumes
  - /data:/data
  x-volumes: &common-cache-volumes
  - /data:/data
  - /cache:/cache

services:
  service-foo:
   <<: *common
   image: docker.io/hello-world:latest

Expected output:

$ docker-compose config
version: '2'
services:
  service-foo:
    image: docker.io/hello-world:latest
    volumes:
    - /data:/data:rw

Actual output:

services:
  service-foo:
    image: docker.io/hello-world:latest
    volumes:
    - /data:/data:rw
    x-volumes:
    - /data:/data
    - /cache:/cache
version: '2'

[ndeloof]

x-* syntax is actually used by the Compose Specification to let Compose implementations define custom extensions (like x-aws-cluster for ECS deployment). Is there any reason you use x-volumes in this example for anchored element?

[hholst80]

Why does compose config remove the top level x- but not the nested x- fields? Inconsistent. If compose care about sub top level extensions it should obliviously also keep the top level, correct?

The reason why I used x-volumes was to keep volumes definitions together in one place for visibility.

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[stale[bot]]

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