Moving discourse instance to a new server

Product Support Self-hosting
4

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"