secrets
https://docs.docker.com/compose/compose-file/compose-file-v3/#secrets
    ! docker system create
https://pythonspeed.com/articles/build-secrets-docker-compose/
    https://habr.com/ru/company/otus/blog/501580/

samples (short)

version: "3.9"
services:
  redis:
    image: redis:latest
    deploy:
      replicas: 1
    secrets:
      - my_secret
      - my_other_secret
secrets:
  my_secret:
    file: ./my_secret.txt
  my_other_secret:
    external: true

samples (long)

version: "3.9"
services:
  redis:
    image: redis:latest
    deploy:
      replicas: 1
    secrets:
      - source: my_secret
        target: redis_secret
        uid: '103'
        gid: '103'
        mode: 0440
secrets:
  my_secret:
    file: ./my_secret.txt
  my_other_secret:
    external: true