These instructions should be considered beta and for those familiar with a standard setup
But right now (2023.02.11) these instructions do not work!! (See Set up Let’s Encrypt with multiple domains / redirects for how to update the letsencrypt setting to add the fullpath part. I’ll update this to reflect those changes Real Soon Now.)
I developed this howto a couple weeks ago but need someone to test and see if this works for someone else. Please reply if you try and let me know whether it works and if anything is unclear.
And on with the show. . .
This howto documents broadly how to set up a multisite setup with 2 additional hosts (3 total).
It assumes that you have a working Discourse official Standard Installation or 2-container installation (Move from standalone container to separate web and data containers).
Domain name for primary site
subdomain for the 2nd site
Suddomain for the 3rd site
Database password (same as DISCOURSE_DB_PASSWORD) or discourse in app.yml
For the sake of simplicity, this is for a main site called =domain=, with two additional sites =two=.=domain= and =three=.=domain=. You can use whatever names you want, but for the sake of this template, not having a different short name (for the database name and title for the sub-forum) and full hostname is a bit easier.
add in hooks after the plugins in app.yml or web_only.yml
before_bundle_exec:
- file:
path: $home/config/multisite.yml
contents: |
=two=:
adapter: postgresql
database: =two=
pool: 25
timeout: 5000
host: data
password: NThmZTNjZjZhOTczNmVj
host_names:
- =two=.=domain=
=three=:
adapter: postgresql
database: =three=
pool: 25
timeout: 5000
host: data
password: NThmZTNjZjZhOTczNmVj
host_names:
- =three=.=domain=
after_db_migrate:
- exec: cd /var/www/discourse && sudo -E -u discourse bundle exec rake multisite:migrate
after_ssl:
# tell letsencrypt what additional certs to get
- replace:
filename: "/etc/runit/1.d/letsencrypt"
from: /-d =domain= /
to: "-d =domain= -d =two=.=domain= -d =three=.=domain="
global: true
# do not redirect all hosts back to the main domain name
- replace:
filename: "/etc/nginx/conf.d/discourse.conf"
from: /if \(\$http_host[^\}]*\}/m
to: ""
Add to the after_postgres section in app.yml or data.yml
- exec: sudo -u postgres createdb =two= || exit 0
- exec:
stdin: |
grant all privileges on database =two= to discourse;
cmd: sudo -u postgres psql =two=
raise_on_fail: false
- exec: /bin/bash -c 'sudo -u postgres psql =two= <<< "alter schema public owner to discourse;"'
- exec: /bin/bash -c 'sudo -u postgres psql =two= <<< "create extension if not exists hstore;"'
- exec: /bin/bash -c 'sudo -u postgres psql =two= <<< "create extension if not exists pg_trgm;"'
- exec: sudo -u postgres createdb =three= || exit 0
- exec:
stdin: |
grant all privileges on database =three= to discourse;
cmd: sudo -u postgres psql =three=
raise_on_fail: false
- exec: /bin/bash -c 'sudo -u postgres psql =three= <<< "alter schema public owner to discourse;"'
- exec: /bin/bash -c 'sudo -u postgres psql =three= <<< "create extension if not exists hstore;"'
- exec: /bin/bash -c 'sudo -u postgres psql =three= <<< "create extension if not exists pg_trgm;"'
After that,
./launcher rebuild app
or
./launcher rebuild data
./launcher rebuild web_only
All I did was copying, adjusting the domains and password and then pasting into the respective files of a fresh installation with 2 containers. 
