Configure Discourse to use a separate PostgreSQL server

No it doesn’t. 


Can you take the same approach for Redis?

remove “templates/redis.template.yml” & add a line in the app.yml file for DISCOURSE_REDIS_HOST

Thanks in advance


Is there an obvious benefit that I’m maybe missing?

(I assume running redis on a separate machine will just add unwanted latency if nothing else)

Just that its managed & 1 less thing to worry about

You don’t have to worry about redis that ships with discourse. I haven’t seen it failing on me in the last 1 year of self hosting discourse.


Thanks @itsbhanusharma,

Do you know what the process would be even if I did?

This article, albeit a little old says to add


which is the same format as the article you so kindly mentioned, so that all makes sense.

Just not sure where to put it (maybe underneath other changes made to the app.yml file or maybe in the "templates/redis.template.yml")

and also

what if any lines or files need to be deleted



That variable should go into the file where you declared postgres variables. Just be warned that exposing redis for a production environment is lethal. (Because of poor security practices of redis itself)


Anu reference or file need to be removed?

I needed to run development discourse (set up following Beginners Guide to Install Discourse for Development using Docker ) using database from another container. To do so, I had to modify the installation steps as follows:

  1. git clone
  2. cd discourse
  3. vim config/database.yml , on the top of the file, make it into:
  prepared_statements: false
  adapter: postgresql
  #database: <%= ENV['DISCOURSE_DEV_DB'] || 'discourse_development' %>
  database: discourse
  username: discourse
  password: yourdbpassword
  host: postgres
  min_messages: warning
  pool: 5
  timeout: 5000
  checkout_timeout: <%= ENV['CHECKOUT_TIMEOUT'] || 5 %>
    ### Don't include the port number here. Change the "port" site setting instead, at /admin/site_settings.
    ### If you change this setting you will need to
    ###   - restart sidekiq if you change this setting
    ###   - rebake all to posts using: `RAILS_ENV=production bundle exec rake posts:rebake`
    - "localhost"
  1. vim bin/docker/boot_dev, find the line starting with docker run, and add a network definition matching the docker network to which your postgres container is attached to: docker run --network my-docker_network-name -d -p 4305:...
  2. ./bin/docker/boot_dev
  3. ./bin/docker/unicorn
  4. you may need to run migrations: docker exec -it discourse_dev /bin/bash -c "cd /src; ./bin/rails db:migrate RAILS_ENV=development"
  5. visit http://localhost:9292/ and log in with credentials you set up earlier on that database

Is there a simpler way to do it, just with environment variables?


This failed for me. Any suggestions on how to fix it ?
I am able to access DB discourse remotely from command line so the connection to DB looks good

Pups::ExecError: cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate' failed with return #<Process::Status: pid 274 exit 1>
Location of failure: /pups/lib/pups/exec_command.rb:112:in `spawn'
exec failed with the params {"cd"=>"$home", "hook"=>"db_migrate", "cmd"=>["su discourse -c 'bundle exec rake db:migrate'"]}
** FAILED TO BOOTSTRAP ** please scroll up and look for earlier error messages, there may be more than one

I got the same error with the following lines in the log above:

rake aborted!
PG::ConnectionBad: could not connect to server: Connection refused
        Is the server running on host "" and accepting
        TCP/IP connections on port 5432?

Currently I am trying to find a fix.

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The only way for me to rebuild with external postgres was the command mentioned earlier:

 rebuild app --docker-args --net=host --skip-mac-address

But in this case unicorn is started with default port 3000. Exposing ports is disabled as well. I cannot explain exactly, but something has changed since Sep '17, probably in launcher code.


Hey guys,

what´s the best practice to migrate from docker based postgre db to dedicated?
The setup of the dedicated is described farther up this thread, right, but how can I then move the data from docker to dedicated db ?
Probably with backup & restore, but is there a tutorial for that available ?

Thanks and greetings,


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Ideally, you have discourse stopped.
Dump your database with pg_dump and restore with pg_restore.
see PostgreSQL Restore Database

Before starting up Discourse using the new database, issue as admin:

grant all privileges on database discourse to discourse;
alter schema public owner to discourse;
create extension if not exists hstore;
create extension if not exists pg_trgm;
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we can also use Hosts ip address instead of using --net=host is the default address for host machine from docker network on unix machines.
Using --net=host restricts us to use -p option as docker argument.


Thank you for really great guide.
Unfortunately I got an error while reproducing it.
Initially I created discourse using launcher for all - app/redis/postgres. And it worked fine.
But with external RDS launcher failed:

root@ip-172-31-42-129:/var/discourse# ./launcher rebuild app
Ensuring launcher is up to date
Fetching origin
Launcher is up-to-date
Stopping old container
+ /usr/bin/docker stop -t 60 app
cd /pups && git pull && git checkout v1.0.3 && /pups/bin/pups --stdin
docker: Error response from daemon: could not get container for No such container:
See 'docker run --help'.
cat: cids/app_bootstrap.cid: No such file or directory
"docker rm" requires at least 1 argument.
See 'docker rm --help'.

Usage:  docker rm [OPTIONS] CONTAINER [CONTAINER...]

Remove one or more containers
rm: cannot remove 'cids/app_bootstrap.cid': No such file or directory
** FAILED TO BOOTSTRAP ** please scroll up and look for earlier error messages, there may be more than one.
./discourse-doctor may help diagnose the problem.

Please advice how to resolve this issue.
Thank you,
Alexander K

Is there any way to pre-create and seed the database that doesn’t require going through the migration steps? We are running on AKS with external Postgres and the db setup seems to take what I consider to be an abnormally long amount of time (~8-9 minutes). Speeding this up would be great. Or is this a known issue in that configuration?

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That’s not a supported configuration.

If you’re building an image, a bunch more stuff than just the database is getting built like a bunch of templates are getting pre-compiled. I think that’s just how long it’s going to take.

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Yes, you can bootstrap it elsewhere and then move the data to your production PostgreSQL.

However this will make updates very cumbersome.


Three things to look for.

One: by default PostgreSQL listens on localhost. Change the listen address in postgresql.conf file as shown below.

listen_addresses = ‘localhost,’

Two: advise PostgreSQL to accept connections from docker images by adding following line to pg_hba.conf file.

host all all scram-sha-256

Restart PostgreSQL service after above two changes.

Three: If still unable to connect then check the firewall that might be blocking incoming connections on port 5432.

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