Compose file and unable to find user

Docker Engine Compose
1

I have simple compose file like this:

services:
  home-assistant:
	container_name: home-assistant
	image: homeassistant/armhf-homeassistant:0.84.3
	volumes:
	  - /opt/has/config:/config
	  - /etc/localtime:/etc/localtime:ro
	restart: on-failure
	network_mode: host
	user: has

I’d like to run this container as user “has” of course, according to specification https://docs.docker.com/compose/compose-file/compose-file-v2/#cpu-and-other-resources all I need is just to set username. But I went into troubles:

root@opi2:/opt/has# docker-compose -f ./docker-compose-hass.yml up -d
Starting home-assistant ...
Starting home-assistant ... error
ERROR: for home-assistant  Cannot start service home-assistant: linux spec user: unable to find user has: no matching entries in passwd file

I suppose container does not have user “has” inside /etc/passwd file. So I followed some tips just to set UID:

root@opi2:/opt/has# id -u has
1001

So let put it into compose file: user: 1001

And run docker-compose now:

root@opi2:/opt/has# docker-compose -f ./docker-compose-hass.yml up -d
ERROR: The Compose file '././docker-compose-hass.yml' is invalid because:
services.home-assistant.user contains an invalid type, it should be a string

Ups! Only string is allowed here. How to manage it? Is it possible to use UID somehow in compose file?

OS & installation details 
Server: Docker Engine - Community
 Engine:
  Version:          18.09.0
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.4
  Git commit:       4d60db4
  Built:            Wed Nov  7 00:17:57 2018
  OS/Arch:          linux/arm
  Experimental:     false

docker-compose version 1.17.1, build unknown
docker-py version: 2.5.1
CPython version: 2.7.15rc1
OpenSSL version: OpenSSL 1.1.0g  2 Nov 2017

Ubuntu 18.04.1 LTS
Linux opi2 4.14.84-sunxi #3 SMP Sat Dec 1 07:18:41 CET 2018 armv7l armv7l armv7l GNU/Linux
2

It clearly says, that it expects a string. If you enter a number, without surrounding it with single or double quotes, yaml will always recognize it as a number. Quotest will turn it into a string.

3

Yes, it’s quite clear itself. But UID/GID is a number, so it’s misleading.
Finally I quoted UID and it works!