Feature request: anchors & aliases

[kpodsiad]

YAML anchors are a feature which let you identify an item and then reference it elsewhere in your file.

services:
  first:
    image: my-image:latest
    environment: &env
      - CONFIG_KEY
      - EXAMPLE_KEY
      - DEMO_VAR
  second:
    image: another-image:latest
    environment: *env