How to do rails db:migrate on multiple shards that are not master slave relationship at once on rails?

Question

I have an app which which uses different database based on the subdomain. So essentially, the schema would be the same, but the data would differ for each databases. But when I release some new features and it would require some schema changes, I would need to run a command that would run on all databases configured in the shards.yml.

database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  pool: 15
  host: localhost
  port: 5432
  username: postgres
  password:

development:
  <<: *default
  database: app_default
production:
  <<: *default
  database: app_default
  username: <%= ENV['BACKEND_DATABASE_USERNAME'] %>
  password: <%= ENV['BACKEND_DATABASE_PASSWORD'] %>

shards.yml

shared: &shared
  adapter: postgresql
  encoding: unicode
  pool: 15
  host: localhost
  username: postgres
  password: 
  port: 5432

octopus:
  environments:
    - development
    - test
    - production
  development:
    default:
      <<: *shared
      database: app
    first:
      <<: *shared
      database: first
    second:
      <<: *shared
      database: second
    ....
  test:
    test:
      host: postgres
      adapter: postgresql
      database: app_test
  production:
    default:
      <<: *shared
      database: app
    first:
      <<: *shared
      database: first
    second:
      <<: *shared
      database: second
    ....

I am using Octopus to set the shard based on subdomain, which works fine. The problems I have are:

1. I cannot do rails db:reset . Getting the error ActiveRecord::StatementInvalid: PG::ObjectInUse: ERROR: cannot drop the currently open database
2. I cannot do rails db:migrate that would migrate on all databases

Traditionalism

Answer 1

You have to add using to your migrations

class CreateComments < ActiveRecord::Migration
  using :first, :second

  def change
    create_table :comments do |t|
      t.belongs_to :page, index: true
      t.text :body

      t.timestamps
    end
  end
end

the above migration will run on both first and second

Misfire

Thanks for taking your time to answer the question. Unfortunately, this solution still won't resolve the rails db:reset error. Although this might just work for the specified shards, I was looking for the migrations to be applied to all the shards. – Traditionalism