My DuggOut Forum is hosted on a subdomain. Though I have verified the parent domain (duggout.com) with Google Webmaster already, it still asked me to verify this subdomain.
Since all the other methods (Google Analytics, CNAME, TXT record, meta tag) failed, I had to go with HTML file upload based verification.
1. SSH into your host machine
2. SSH into the docker container
cd /var/discourse (or wherever discourse is installed)
./launcher ssh app
3. Create the Google provided HTML file under /var/www/discourse/public directory
Now, go and hit the URL –
You will see it working and your Webmaster verification is complete.