Create Prometheus::Internal lib

- Create the lib since it needs to be called in PrometheusService as
well as the current SelfMonitoring::Project::CreateService.

lib/gitlab/database_importers/self_monitoring/project/create_service.rb

@@ -176,19 +176,11 @@ module Gitlab
           end
 
           def prometheus_enabled?
-            Gitlab.config.prometheus.enable if Gitlab.config.prometheus
-          rescue Settingslogic::MissingSetting
-            log_error('prometheus.enable is not present in config/gitlab.yml')
-
-            false
+            ::Gitlab::Prometheus::Internal.prometheus_enabled?
           end
 
           def prometheus_listen_address
-            Gitlab.config.prometheus.listen_address.to_s if Gitlab.config.prometheus
-          rescue Settingslogic::MissingSetting
-            log_error('Prometheus listen_address is not present in config/gitlab.yml')
-
-            nil
+            ::Gitlab::Prometheus::Internal.listen_address
           end
 
           def instance_admins
@@ -231,23 +223,7 @@ module Gitlab
           end
 
           def internal_prometheus_listen_address_uri
-            if prometheus_listen_address.starts_with?('0.0.0.0:')
-              # 0.0.0.0:9090
-              port = ':' + prometheus_listen_address.split(':').second
-              'http://localhost' + port
-
-            elsif prometheus_listen_address.starts_with?(':')
-              # :9090
-              'http://localhost' + prometheus_listen_address
-
-            elsif prometheus_listen_address.starts_with?('http')
-              # https://localhost:9090
-              prometheus_listen_address
-
-            else
-              # localhost:9090
-              'http://' + prometheus_listen_address
-            end
+            ::Gitlab::Prometheus::Internal.uri
           end
 
           def prometheus_service_attributes

lib/gitlab/prometheus/internal.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Prometheus
+    class Internal
+      def self.uri
+        return if listen_address.blank?
+
+        if listen_address.starts_with?('0.0.0.0:')
+          # 0.0.0.0:9090
+          port = ':' + listen_address.split(':').second
+          'http://localhost' + port
+
+        elsif listen_address.starts_with?(':')
+          # :9090
+          'http://localhost' + listen_address
+
+        elsif listen_address.starts_with?('http')
+          # https://localhost:9090
+          listen_address
+
+        else
+          # localhost:9090
+          'http://' + listen_address
+        end
+      end
+
+      def self.listen_address
+        Gitlab.config.prometheus.listen_address.to_s if Gitlab.config.prometheus
+      rescue Settingslogic::MissingSetting
+        Gitlab::AppLogger.error('Prometheus listen_address is not present in config/gitlab.yml')
+
+        nil
+      end
+
+      def self.prometheus_enabled?
+        Gitlab.config.prometheus.enable if Gitlab.config.prometheus
+      rescue Settingslogic::MissingSetting
+        Gitlab::AppLogger.error('prometheus.enable is not present in config/gitlab.yml')
+
+        false
+      end
+    end
+  end
+end

spec/lib/gitlab/prometheus/internal_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Prometheus::Internal do
+  let(:listen_address) { 'localhost:9090' }
+
+  let(:prometheus_settings) do
+    {
+      enable: true,
+      listen_address: listen_address
+    }
+  end
+
+  before do
+    stub_config(prometheus: prometheus_settings)
+  end
+
+  describe '.uri' do
+    shared_examples 'returns valid uri' do |uri_string|
+      it do
+        expect(described_class.uri).to eq(uri_string)
+        expect { Addressable::URI.parse(described_class.uri) }.not_to raise_error
+      end
+    end
+
+    it_behaves_like 'returns valid uri', 'http://localhost:9090'
+
+    context 'with non default prometheus address' do
+      let(:listen_address) { 'https://localhost:9090' }
+
+      it_behaves_like 'returns valid uri', 'https://localhost:9090'
+
+      context 'with :9090 symbol' do
+        let(:listen_address) { :':9090' }
+
+        it_behaves_like 'returns valid uri', 'http://localhost:9090'
+      end
+
+      context 'with 0.0.0.0:9090' do
+        let(:listen_address) { '0.0.0.0:9090' }
+
+        it_behaves_like 'returns valid uri', 'http://localhost:9090'
+      end
+    end
+
+    context 'when listen_address is nil' do
+      let(:listen_address) { nil }
+
+      it 'does not fail' do
+        expect(described_class.uri).to eq(nil)
+      end
+    end
+
+    context 'when prometheus listen address is blank in gitlab.yml' do
+      let(:listen_address) { '' }
+
+      it 'does not configure prometheus' do
+        expect(described_class.uri).to eq(nil)
+      end
+    end
+  end
+
+  describe 'prometheus_enabled?' do
+    it 'returns correct value' do
+      expect(described_class.prometheus_enabled?).to eq(true)
+    end
+
+    context 'when prometheus setting is disabled in gitlab.yml' do
+      let(:prometheus_settings) do
+        {
+          enable: false,
+          listen_address: listen_address
+        }
+      end
+
+      it 'returns correct value' do
+        expect(described_class.prometheus_enabled?).to eq(false)
+      end
+    end
+
+    context 'when prometheus setting is not present in gitlab.yml' do
+      before do
+        allow(Gitlab.config).to receive(:prometheus).and_raise(Settingslogic::MissingSetting)
+      end
+
+      it 'does not fail' do
+        expect(described_class.prometheus_enabled?).to eq(false)
+      end
+    end
+  end
+
+  describe '.listen_address' do
+    it 'returns correct value' do
+      expect(described_class.listen_address).to eq(listen_address)
+    end
+
+    context 'when prometheus setting is not present in gitlab.yml' do
+      before do
+        allow(Gitlab.config).to receive(:prometheus).and_raise(Settingslogic::MissingSetting)
+      end
+
+      it 'does not fail' do
+        expect(described_class.listen_address).to eq(nil)
+      end
+    end
+  end
+end