testcontainers-postgres simplifies the creation and management of Postgres containers for testing purposes using the Testcontainers library.

Add the library to the test section in your application's Gemfile:

group :test do
  gem "testcontainers-postgres"
end

And then execute:

$ bundle install

Or install it yourself as:

$ gem install testcontainers-postgres

To use the library, you first need to require it:

require "testcontainers/postgres"

Create a new instance of the Testcontainers::PostgresContainer class:

container = Testcontainers::PostgresContainer.new

This creates a new container with the default Postgres image, user, password, and database. You can customize these by passing arguments to the constructor:

container = Testcontainers::PostgresContainer.new("postgres:11", username: "custom_user", password: "custom_pass", database: "custom_db")

Start the container:

container.start

Stop the container when you're done:

container.stop

Once the container is running, you can obtain the connection details using the following methods:

host = container.host
port = container.first_mapped_port

Or, you can generate a full database URL:

database_url = container.database_url

Use this URL to connect to the Postgres container using your preferred postgres client library.

You can also customize the container using the following methods:

container.with_database("custom_db")
container.with_username("custom_user")
container.with_password("custom_pass")

Here's a complete example of how to use testcontainers-postgres to create a container, connect to it, and run a simple query:

require "testcontainers/postgres"
require "pg"

container = Testcontainers::PostgresContainer.new
container.start

client = PG.connect(container.database_url)

result = client.exec("SELECT 1 AS number")
result.each do |row|
  puts row.inspect
end

client.close
container.stop

This example creates a Postgres container, connects to it using the pg gem, runs a simple SELECT 1 as number query, and then stops the container.

You can manage the container in the before(:suite) / after(:suite) blocks in your spec_helper.rb:

RSpec.configure do |config|
  # This helps us to have access to the `RSpec.configuration.postgres_container` without using global variables.
  config.add_setting :postgres_container, default: nil

  config.before(:suite) do
    config.postgres_container = Testcontainers::PostgresContainer.new.start
    ENV["DATABASE_URL"] = config.postgres_container.database_url # or you can expose it to a fixed port and use database.yml for configuration
  end

  config.after(:suite) do
    config.postgres_container&.stop
    config.postgres_container&.remove
  end
end

Bug reports and pull requests are welcome on GitHub at https://github.com/testcontainers/testcontainers-ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Testcontainers project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.