1 files changed, 195 insertions, 0 deletions
diff --git a/spec/services/prometheus/proxy_service_spec.rb b/spec/services/prometheus/proxy_service_spec.rb
new file mode 100644
index 00000000000..4bdb20de4c9
--- /dev/null
+++ b/spec/services/prometheus/proxy_service_spec.rb
@@ -0,0 +1,195 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Prometheus::ProxyService do
+  include ReactiveCachingHelpers
+
+  set(:project) { create(:project) }
+  set(:environment) { create(:environment, project: project) }
+
+  describe '#initialize' do
+    let(:params) { ActionController::Parameters.new(query: '1').permit! }
+
+    it 'initializes attributes' do
+      result = described_class.new(environment, 'GET', 'query', params)
+
+      expect(result.proxyable).to eq(environment)
+      expect(result.method).to eq('GET')
+      expect(result.path).to eq('query')
+      expect(result.params).to eq('query' => '1')
+    end
+
+    it 'converts ActionController::Parameters into hash' do
+      result = described_class.new(environment, 'GET', 'query', params)
+
+      expect(result.params).to be_an_instance_of(Hash)
+    end
+
+    context 'with unknown params' do
+      let(:params) { ActionController::Parameters.new(query: '1', other_param: 'val').permit! }
+
+      it 'filters unknown params' do
+        result = described_class.new(environment, 'GET', 'query', params)
+
+        expect(result.params).to eq('query' => '1')
+      end
+    end
+  end
+
+  describe '#execute' do
+    let(:prometheus_adapter) { instance_double(PrometheusService) }
+    let(:params) { ActionController::Parameters.new(query: '1').permit! }
+
+    subject { described_class.new(environment, 'GET', 'query', params) }
+
+    context 'when prometheus_adapter is nil' do
+      before do
+        allow(environment).to receive(:prometheus_adapter).and_return(nil)
+      end
+
+      it 'returns error' do
+        expect(subject.execute).to eq(
+          status: :error,
+          message: 'No prometheus server found',
+          http_status: :service_unavailable
+        )
+      end
+    end
+
+    context 'when prometheus_adapter cannot query' do
+      before do
+        allow(environment).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+        allow(prometheus_adapter).to receive(:can_query?).and_return(false)
+      end
+
+      it 'returns error' do
+        expect(subject.execute).to eq(
+          status: :error,
+          message: 'No prometheus server found',
+          http_status: :service_unavailable
+        )
+      end
+    end
+
+    context 'cannot proxy' do
+      subject { described_class.new(environment, 'POST', 'garbage', params) }
+
+      it 'returns error' do
+        expect(subject.execute).to eq(
+          message: 'Proxy support for this API is not available currently',
+          status: :error
+        )
+      end
+    end
+
+    context 'with caching', :use_clean_rails_memory_store_caching do
+      let(:return_value) { { 'http_status' => 200, 'body' => 'body' } }
+
+      let(:opts) do
+        [environment.class.name, environment.id, 'GET', 'query', { 'query' => '1' }]
+      end
+
+      before do
+        allow(environment).to receive(:prometheus_adapter)
+          .and_return(prometheus_adapter)
+        allow(prometheus_adapter).to receive(:can_query?).and_return(true)
+      end
+
+      context 'when value present in cache' do
+        before do
+          stub_reactive_cache(subject, return_value, opts)
+        end
+
+        it 'returns cached value' do
+          result = subject.execute
+
+          expect(result[:http_status]).to eq(return_value[:http_status])
+          expect(result[:body]).to eq(return_value[:body])
+        end
+      end
+
+      context 'when value not present in cache' do
+        it 'returns nil' do
+          expect(ReactiveCachingWorker)
+            .to receive(:perform_async)
+            .with(subject.class, subject.id, *opts)
+
+          result = subject.execute
+
+          expect(result).to eq(nil)
+        end
+      end
+    end
+
+    context 'call prometheus api' do
+      let(:prometheus_client) { instance_double(Gitlab::PrometheusClient) }
+
+      before do
+        synchronous_reactive_cache(subject)
+
+        allow(environment).to receive(:prometheus_adapter)
+          .and_return(prometheus_adapter)
+        allow(prometheus_adapter).to receive(:can_query?).and_return(true)
+        allow(prometheus_adapter).to receive(:prometheus_client_wrapper)
+          .and_return(prometheus_client)
+      end
+
+      context 'connection to prometheus server succeeds' do
+        let(:rest_client_response) { instance_double(RestClient::Response) }
+        let(:prometheus_http_status_code) { 400 }
+
+        let(:response_body) do
+          '{"status":"error","errorType":"bad_data","error":"parse error at char 1: no expression found in input"}'
+        end
+
+        before do
+          allow(prometheus_client).to receive(:proxy).and_return(rest_client_response)
+
+          allow(rest_client_response).to receive(:code)
+            .and_return(prometheus_http_status_code)
+          allow(rest_client_response).to receive(:body).and_return(response_body)
+        end
+
+        it 'returns the http status code and body from prometheus' do
+          expect(subject.execute).to eq(
+            http_status: prometheus_http_status_code,
+            body: response_body,
+            status: :success
+          )
+        end
+      end
+
+      context 'connection to prometheus server fails' do
+        context 'prometheus client raises Gitlab::PrometheusClient::Error' do
+          before do
+            allow(prometheus_client).to receive(:proxy)
+              .and_raise(Gitlab::PrometheusClient::Error, 'Network connection error')
+          end
+
+          it 'returns error' do
+            expect(subject.execute).to eq(
+              status: :error,
+              message: 'Network connection error',
+              http_status: :service_unavailable
+            )
+          end
+        end
+      end
+    end
+  end
+
+  describe '.from_cache' do
+    it 'initializes an instance of ProxyService class' do
+      result = described_class.from_cache(
+        environment.class.name, environment.id, 'GET', 'query', { 'query' => '1' }
+      )
+
+      expect(result).to be_an_instance_of(described_class)
+      expect(result.proxyable).to eq(environment)
+      expect(result.method).to eq('GET')
+      expect(result.path).to eq('query')
+      expect(result.params).to eq('query' => '1')
+    end
+  end
+end