Discourse docker container has trouble reaching DNS

@sam I can get internet by IP adress

wget http://178.172.160.5
--2018-04-30 07:39:05--  http://178.172.160.5/
Connecting to 178.172.160.5:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://www.tut.by/ [following]
--2018-04-30 07:39:06--  https://www.tut.by/
Resolving www.tut.by (www.tut.by)... failed: Temporary failure in name resolution.
wget: unable to resolve host address ‘www.tut.by’

Could you help me setup DNS settings for docker?