A simple Ruby on Rails health check endpoint

health_controller.rb

# ./app/controllers/health_controller.rb

class HealthController < ApplicationController
  skip_before_action :authenticate!

  def index
    current_time_str = ActiveRecord::Base.connection.execute("SELECT CURRENT_TIME;").first["current_time"]
    current_time = current_time_str.to_datetime

    render json: {
      success: true,
      now: current_time.utc
    }

  rescue => e
    puts e
    Rollbar.error(e) # or another error monitoring service

    render json: {
      success: false,
    }, status: 500
  end
end

health_controller_spec.rb

# ./spec/controllers/health_controller_spec.rb

require 'rails_helper'

RSpec.describe HealthController do
  describe '#index' do
    def go!
      get :index
    end

    it_behaves_like 'ok'

    it 'returns valid JSON' do
      go!

      expect(response_json[:success]).to eq(true)
    end

    it 'gets the date from Postgres' do
      go!

      expect(response_json[:now]).not_to be_nil
      expect(response_json[:now].to_datetime).not_to be_nil
    end
  end
end

shared_examples.rb

# ./spec/support/shared_examples.rb

RSpec.shared_examples 'ok' do
  it 'returns OK' do
    go!
    expect(response).to be_ok
    expect(response_json[:error]).to be_nil
  end
end

test_helpers.rb

# ./spec/support/helpers/test_helpers.rb

module Helpers
  module Test
    def response_json
      JSON(response.body).with_indifferent_access
    end
  end
end