Make production db pool size configurable

config/application.yml.example

@@ -79,6 +79,10 @@ development:
   database_host: ''
   database_name: ''
   database_password: ''
+  database_pool_idp: '5'
+  database_pool_worker: '5'
+  database_readonly_password: ''
+  database_readonly_username: ''
   database_timeout: '5000'
   database_username: ''
   domain_name: 'localhost:3000'
@@ -256,6 +260,10 @@ test:
   database_host: ''
   database_name: ''
   database_password: ''
+  database_pool_idp:
+  database_pool_worker:
+  database_readonly_password: ''
+  database_readonly_username: ''
   database_timeout: '5000'
   database_username: ''
   dashboard_api_token: '123ABC'

config/database.yml

@@ -1,3 +1,5 @@
+<% require 'production_database_configuration' %>
+
 postgresql: &postgresql
   adapter: postgresql
   encoding: utf8
@@ -33,6 +35,6 @@ production:
   username: <%= Figaro.env.database_username! %>
   host: <%= Figaro.env.database_host! %>
   password: <%= Figaro.env.database_password! %>
-  pool: <%= (File.exist?('/etc/login.gov/info') && File.read('/etc/login.gov/info/role').chomp == 'worker') ? 26 : 5 %>
+  pool: <%= ProductionDatabaseConfiguration.pool %>
   sslmode: 'verify-full'
   sslrootcert: '/usr/local/share/aws/rds-combined-ca-bundle.pem'

lib/production_database_configuration.rb

@@ -0,0 +1,14 @@
+class ProductionDatabaseConfiguration
+  def self.pool
+    env = Figaro.env
+    role = File.read('/etc/login.gov/info') if File.exist?('/etc/login.gov/info')
+    case role
+    when 'idp'
+      env.database_pool_idp.presence || 5
+    when 'worker'
+      env.database_pool_worker.presence || 26
+    else
+      5
+    end
+  end
+end

spec/lib/production_database_configuration_spec.rb

@@ -0,0 +1,69 @@
+require 'rails_helper'
+
+describe ProductionDatabaseConfiguration do
+  describe '.pool' do
+    context 'when the app is running on an idp host' do
+      before { stub_role_config('idp') }
+
+      it 'returns the idp pool size' do
+        allow(Figaro.env).to receive(:database_pool_idp).and_return(7)
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(7)
+      end
+
+      it 'defaults to 5' do
+        allow(Figaro.env).to receive(:database_pool_idp).and_return(nil)
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(5)
+
+        allow(Figaro.env).to receive(:database_pool_idp).and_return('')
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(5)
+      end
+    end
+
+    context 'when the app is running on a worker host' do
+      before { stub_role_config('worker') }
+
+      it 'returns the worker pool size' do
+        allow(Figaro.env).to receive(:database_pool_worker).and_return(8)
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(8)
+      end
+
+      it 'defaults to 26' do
+        allow(Figaro.env).to receive(:database_pool_worker).and_return(nil)
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(26)
+
+        allow(Figaro.env).to receive(:database_pool_worker).and_return('')
+
+        expect(ProductionDatabaseConfiguration.pool).to eq(26)
+      end
+    end
+
+    context 'when the app is running on an host with an ambigous role' do
+      before { stub_role_config('fake') }
+
+      it 'returns a default of 5' do
+        expect(ProductionDatabaseConfiguration.pool).to eq(5)
+      end
+    end
+
+    context 'when the app is running on a host without a role config file' do
+      before do
+        allow(File).to receive(:exist?).with('/etc/login.gov/info').and_return(false)
+      end
+
+      it 'returns 5 and does not read the role config' do
+        expect(File).to_not receive(:read)
+        expect(ProductionDatabaseConfiguration.pool).to eq(5)
+      end
+    end
+  end
+
+  def stub_role_config(role)
+    allow(File).to receive(:exist?).with('/etc/login.gov/info').and_return(true)
+    allow(File).to receive(:read).with('/etc/login.gov/info').and_return(role)
+  end
+end