Use anchors in docker-compose files

[joemaller]

YAML spec on Alias Nodes (&anchors and *aliases)

Something like this could work?

services:
  db:
    image: &db_img mariadb:11.0.3

  wp:
    image: &wp_img ideasonpurpose/wordpress:6.3

  other_db_service:
    image: *db_img   // reference returns "mariadb:11.0.3"

  other_wp_service:
    image: *wp_img // reference returns "ideasonpurpose/wordpress:6.3"