ECO-240/improved-healthcheck

app/controllers/health_controller.rb

@@ -1,5 +1,44 @@
 class HealthController < ApplicationController
+
   def index
-    head :ok
+    database_check_results = check_db_connections
+    if all_database_healthy?(database_check_results)
+      render json: {status: "ok"}, status: :ok
+    else
+      render json: {status: "fail"}, status: :internal_server_error
+    end
+  rescue StandardError
+    render json: {status: "fail"}, status: :internal_server_error
+  end
+
+  private
+  def all_database_healthy?(database_check_results)
+    database_check_results.values.all? { |status| status[:status] == "ok" }
+  end
+
+  def check_db_connections
+    db_status = {}
+    databases.each do |role, connection|
+      db_status[role] = perform_health_check(connection)
+    ensure
+      ActiveRecord::Base.clear_active_connections!
+    end
+    db_status
+  end
+
+  def databases
+    {
+      primary: ActiveRecord::Base.connected_to(role: :writing) { ApplicationRecord.connection },
+      datahub: ActiveRecord::Base.connected_to(role: :reading) { DatahubRecord.connection }
+    }
+  end
+
+  def perform_health_check(connection)
+    if connection
+      connection.execute('SELECT 1')
+      {status: 'ok'}
+    else
+      {status: 'fail'}
+    end
   end
 end

spec/features/health_spec.rb

@@ -1,9 +1,50 @@
 require 'rails_helper'
 
 RSpec.feature "Healthcheck", type: :feature do
-  scenario 'As a healthcheck bot I want to check if everything is ok' do
-    visit health_path
+  context 'when healthcheck passes' do
+    scenario 'With healthcheck I want to check if everything is ok' do
+      visit health_path
 
-    expect(page.status_code).to be(200)
+      expect(page.status_code).to be(200)
+
+      returned_data = JSON.parse(page.body)
+
+      expect(returned_data["status"]).to eq("ok")
+    end
+  end
+
+  context 'when healthcheck fails' do
+    scenario 'unexpected error in health check' do
+      allow_any_instance_of(HealthController).to receive(:all_database_healthy?).and_raise(StandardError, 'Unexpected error')
+
+      visit health_path
+
+      expect(page.status_code).to be(500)
+      returned_data = JSON.parse(page.body)
+
+      expect(returned_data["status"]).to eq("fail")
+    end
+
+    scenario 'primary database fails' do
+      allow(ApplicationRecord.connection).to receive(:execute).and_raise(StandardError, 'Something went wrong in primary db')
+
+      visit health_path
+
+      expect(page.status_code).to be(500)
+      returned_data = JSON.parse(page.body)
+
+      expect(returned_data["status"]).to eq("fail")
+    end
+
+    scenario 'datahub database fails' do
+      allow(DatahubRecord.connection).to receive(:execute).and_raise(StandardError, 'Something went wrong in datahub db')
+
+      visit health_path
+
+      expect(page.status_code).to be(500)
+      returned_data = JSON.parse(page.body)
+
+      expect(returned_data["status"]).to eq("fail")
+    end
   end
 end