Ruby and Ruby on Rails

Introduction

We provide images for Ruby 3.0 and above, built on the official Ruby alpine Docker images.

Below we assume that you're attempting to get a Rails app deployed on Lagoon, although most of the details described are really framework-neutral.

Getting Rails running on Lagoon

Responding to requests

The Ruby on Rails example in the Lagoon examples repository is instructive here.

In the docker-compose.yml we set up a service named ruby, which is the primary service that will be processing any dynamic requests.

If you look at the dockerfile specified for the ruby service, you'll see that we're exposing port 3000. The nginx service will direct any requests for non-static assets to the ruby service on this port (see the nginx configuration file for more details).

Logging

The Lagoon logging infrastructure is described in the docs here. Essentially, in order to make use of the infrastructure, logs need to be sent via a UDP message to udp://application-logs.lagoon.svc:5140.

In our Rails example, we're importing the logstash-logger gem, and then in our config/application.rb we're initializing it with the following:

config/application.rb

    if ENV.has_key?('LAGOON_PROJECT') && ENV.has_key?('LAGOON_ENVIRONMENT') then
      lagoon_namespace = ENV['LAGOON_PROJECT'] + "-" + ENV['LAGOON_ENVIRONMENT']
      LogStashLogger.configure do |config|
        config.customize_event do |event|
          event["type"] = lagoon_namespace
        end
      end

      config.logstash.host = 'application-logs.lagoon.svc'
      config.logstash.type = :udp
      config.logstash.port = 5140
    end

Database configuration

The example uses our PostgreSQL image (see the docker-compose.yml file). Configuring database access in Rails for Lagoon is very straightforward. Since Lagoon injects the database host, name, and credentials as environment variables, we can change our config/database.yml to be aware of these env vars, and consume them if they exist.

config/database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: <%= ENV.fetch("POSTGRES_USERNAME") { "drupal" } %>
  password: <%= ENV.fetch("POSTGRES_PASSWORD") { "drupal" } %>
  host: <%= ENV.fetch("POSTGRES_HOST") { "postgres" } %>
  database: <%= ENV.fetch("('POSTGRES_DATABASE'") { "drupal" } %>