Styjun

I have a rails application that accesses two databases: a read replica and it's own database configured through a standard database.yml file.

There are certain models that access the read replica, and I use establish_connection to dynamically switch over to the replica:

class MyReadReplicaDbBase < ActiveRecord::Base
 self.abstract_class = true
 establish_connection READ_REPLICA_DB
end

class User < MyReadReplicaDbBase
end

Actual environments work well with this setup, but while testing on travis, I need to set up two databases using an approach like this:

language: ruby

cache: bundler

rvm:
 - 2.5.1

services:
 - docker
 - redis-server

env:
 global:
 - DB_URL=postgres://postgres@localhost/travis_ci_test
 - READ_REPLICA_DB_URL=postgres://postgres@localhost/travis_ci_read_replica_test


# https://github.com/travis-ci/travis-ci/issues/9624#issuecomment-389537036
before_install:
 - sudo sed -i -e '/local.*peer/s/postgres/all/' -e 's/peer|md5/trust/g' /etc/postgresql/*/main/pg_hba.conf
 - sudo service postgresql restart
 - sleep 1
 - gem update --system
 - gem install bundler

sudo: required
dist: xenial
addons:
 postgresql: "10"
 apt:
 packages:
 - postgresql-10
 - postgresql-client-10
 env:
 global:
 - PGPORT=5433

before_script:
 - cp config/database.yml.travis config/database.yml
 - psql -c 'create database travis_ci_test;' -U postgres
 - psql -c 'create database travis_ci_read_replica_test' -U postgres


script:
 - bundle exec rails db:migrate RAILS_ENV=test
 - bundle exec rspec -f d

Is there a standard approach to load the schema in the replica database for testing? Can I run something like the following?

rake:db:schema:load --database read_replica_db

I understand this won't work because it will pull the default environment to set up that database.

So I got it working using a Personal access token and copying the schema over using this script

#load_read_replica_schema.rb
#!/home/travis/.rvm/rubies/ruby-2.5.1/bin/ruby

def install_gems()
 system('gem install pg')
 system('gem install activerecord -v=5.2.2')
end

def get_read_replica_schema_file
 require 'active_record'
 require 'active_record/tasks/database_tasks'
 require 'active_record/tasks/postgresql_database_tasks'

 curl_command = "curl -s https://#ENV['PERSONAL_ACCESS_TOKEN']@raw.githubusercontent.com/<owner>/<repo>/master/db/schema.rb -o read_replica_schema.rb"
 system(curl_command)


 ActiveRecord::Tasks::DatabaseTasks.load_schema('postgres://postgres:@localhost/travis_ci_read_replica_test', :ruby, 'read_replica_schema.rb', :test)
end


install_gems()
get_read_replica_schema_file()

Similarly updated the script to run on the travis.yaml script with a script

before_script:
 - cp config/database.yml.travis config/database.yml
 - psql -c 'create database travis_ci_test;' -U postgres
 - psql -c 'create database travis_ci_read_replica_test' -U postgres

script:
 - ./load_read_replica_api_schema.rb
 - bundle exec rails db:migrate RAILS_ENV=test
 - bundle exec rspec -f d