Moving discourse instance to a new server

[Headless]

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Hello,

I first want to thank you for any support you may offer. With that being said, I would like to discuss my issue and then my goals for my self-hosted Discourse instance.

Problem

I currently use Hetzner as my server that is hosting a discourse instance. I have attached volumes for Uploads , Backups. The current Docker containers and images, as well as the app.yml and etc, are hosted on the server itself under /var/discourse.

I have had this server over the course of 3-4+ years, and throughout that time, I have always run into the issue with space on the server itself (not volumes). Anytime I wanted to rebuild the app or relaunch the app, I would run into space issues as it would install the images and Docker containers to the local server rather than a volume. I would constantly need to remove Docker and any images/containers and do a fresh reinstall so I can rebuild. I also believe the SQL data is attached to the local server instead of a volume.

Goals

I am not sure what would be best for me going forward. Is it moving specific folders or files to a new volume for the Postgres DB and Docker images, and if so, I would love support on how to do that? Or starting from scratch with a fresh server, creating a backup of the server, and restoring on a new server with all volumes in properly configured locations?

---

With all this being said, I would love some support on configuring the app.yml to properly have volumes for everything that takes up space, so I can individually scale when backups, uploads, db, or docker images, for example, need it.

I can provide my app.yml file later today, as I am currently at work and looking to get ahead of the game.

[Lee_Ars]

I do my discourse hosting on AWS, and I have had great success so far in keeping /var/discourse on its own mountable EBS volume and attaching that volume to different EC2 instances as I’ve needed to migrate. I even fully changed architecture from x64 to ARM (I switched EC2 instances from a t3a.large to an r7g.large) and after re-mounting the /var/discourse volume, I was back online after a simple launcher rebuild app even with the architecture switch.

Bottom line, if your /var/discourse is stored in a mountable volume, then you have the entire state of your forum in an essentially swing-mountable state. As long as you can set up a host and install docker on it, you can mount /var/discourse to it, run a launcher rebuild app, and be up and running. (Assuming things like hostname and other stuff specified in app.yml remain constant between hosts.)

[Headless]

Could you possibly provide a example app.yml for this setup? As well as is it as simple as a move from “/var/discourse” content to a different volume or do I need to clone the repo into the new volume.

---

What also about the database files?

[Lee_Ars]

Here’s a sanitized copy of my current working app.yml:

## this is the all-in-one, standalone Discourse Docker container template
##
## After making changes to this file, you MUST rebuild
## /var/discourse/launcher rebuild app
##
## BE *VERY* CAREFUL WHEN EDITING!
## YAML FILES ARE SUPER SUPER SENSITIVE TO MISTAKES IN WHITESPACE OR ALIGNMENT!
## visit http://www.yamllint.com/ to validate this file as needed

templates:
  - "templates/postgres.template.yml"
  - "templates/redis.template.yml"
  - "templates/web.template.yml"
  - "templates/web.ratelimited.template.yml"
  - "templates/web.ssl.template.yml"
  - "templates/web.letsencrypt.ssl.template.yml"
  - "templates/cloudflare.template.yml"

## which TCP/IP ports should this container expose?
## If you want Discourse to share a port with another webserver like Apache or nginx,
## see https://meta.discourse.org/t/17247 for details
expose:
  - "80:80"   # http
  - "443:443" # https

params:
  db_default_text_search_config: "pg_catalog.english"

  ## Set db_shared_buffers to a max of 25% of the total memory.
  ## will be set automatically by bootstrap based on detected RAM, or you can override
  db_shared_buffers: "4096MB"

  ## can improve sorting performance, but adds memory usage per-connection
  db_work_mem: "40MB"

  ## Which Git revision should this container use? (default: tests-passed)
  #version: tests-passed

env:
  LC_ALL: en_US.UTF-8
  LANG: en_US.UTF-8
  LANGUAGE: en_US.UTF-8
  # DISCOURSE_DEFAULT_LOCALE: en

  ## How many concurrent web requests are supported? Depends on memory and CPU cores.
  ## will be set automatically by bootstrap based on detected CPUs, or you can override

  ## Changed by Lee on 2025/8/2
  # UNICORN_WORKERS: 8
  UNICORN_WORKERS: 10

  ## TODO: The domain name this Discourse instance will respond to
  ## Required. Discourse will not work with a bare IP number.
  DISCOURSE_HOSTNAME: discourse.spacecityweather.com

  ## TODO: List of comma delimited emails that will be made admin and developer
  ## on initial signup example 'user1@example.com,user2@example.com'
  DISCOURSE_DEVELOPER_EMAILS: [redacted]

  ## TODO: The SMTP mail server used to validate new accounts and send notifications
  # SMTP ADDRESS is required
  # WARNING: SMTP password should be wrapped in quotes to avoid problems
  DISCOURSE_SMTP_ADDRESS: [redacted]
  DISCOURSE_SMTP_PORT: [redacted]
  DISCOURSE_SMTP_USER_NAME: [redacted]
  DISCOURSE_SMTP_PASSWORD: [redacted]
  DISCOURSE_SMTP_DOMAIN: [redacted]
  DISCOURSE_NOTIFICATION_EMAIL: [redacted]

  ## If you added the Lets Encrypt template, uncomment below to get a free SSL certificate
  LETSENCRYPT_ACCOUNT_EMAIL: [redacted]

  ## The maxmind geolocation IP account ID and license key for IP address lookups
  ## see https://meta.discourse.org/t/-/173941 for details
  DISCOURSE_MAXMIND_ACCOUNT_ID: [redacted]
  DISCOURSE_MAXMIND_LICENSE_KEY: [redacted]

  ## S3 backup crap
  ## Added by Lee on 2025/7/20
  DISCOURSE_USE_S3: true
  DISCOURSE_S3_REGION: [redacted]
  DISCOURSE_S3_USE_IAM_PROFILE: true
  DISCOURSE_S3_BACKUP_BUCKET: [redacted]
  DISCOURSE_BACKUP_LOCATION: s3

  ## Maybe fix sidekiq using too much memory errors?
  UNICORN_SIDEKIQ_MAX_RSS: 1024

  ## Added by Lee on 2025/8/2
  SIDEKIQ_CONCURRENCY: 6
  RUBY_GC_HEAP_GROWTH_MAX_SLOTS: 40000
  RUBY_GC_HEAP_GROWTH_FACTOR: 1.1
  RUBY_GLOBAL_METHOD_CACHE_SIZE: 131072
  MALLOC_ARENA_MAX: 2

## The Docker container is stateless; all data is stored in /shared
volumes:
  - volume:
      host: /var/discourse/shared/standalone
      guest: /shared
  - volume:
      host: /var/discourse/shared/standalone/log/var-log
      guest: /var/log

## Docker args?
docker_args: "--add-host spacecityweather.com:[redacted] --add-host theeyewall.com:[redacted]"

## Plugins go here
## see https://meta.discourse.org/t/19157 for details
hooks:
  after_code:
    - exec:
        cd: $home/plugins
        cmd:
          - git clone https://github.com/discourse/docker_manager.git

## Any custom commands to run after building
run:
  - exec: echo "Beginning of custom commands"
  ## If you want to set the 'From' email address for your first registration, uncomment and change:
  ## After getting the first signup email, re-comment the line. It only needs to run once.
  #- exec: rails r "SiteSetting.notification_email='info@unconfigured.discourse.org'"
  - exec: echo "End of custom commands"

[Headless]

And all the contents of the DB are stored in /var/discourse? So if I move all the contents of /var/discourse to a mountable volume, it should continue to use all the existing data?

[Lee_Ars]

I’m using the standard single-container self hosted install, so it’s all set up however the defaults are set!

[Headless]

Question, even though I moved the /discourse folder over to a mountable volume, I still am struggling with docker. As containers and images are still being ran on the local drive instead of a volume. Any idea on how to fix this?