Merge branch '5029-support-cluster-metrics-ce' into 'master'

Refactoring changes to support cluster metrics in EE

Closes #42820

See merge request gitlab-org/gitlab-ce!17336

11 files changed, 226 insertions, 244 deletions

diff --git a/spec/controllers/projects/deployments_controller_spec.rb b/spec/controllers/projects/deployments_controller_spec.rb
index 73e7921fab7..6c67dfde63a 100644
--- a/spec/controllers/projects/deployments_controller_spec.rb
+++ b/spec/controllers/projects/deployments_controller_spec.rb
@@ -129,10 +129,10 @@ describe Projects::DeploymentsController do
     end
 
     context 'when metrics are enabled' do
-      let(:prometheus_service) { double('prometheus_service') }
+      let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true) }
 
       before do
-        allow(deployment.project).to receive(:prometheus_service).and_return(prometheus_service)
+        allow(deployment).to receive(:prometheus_adapter).and_return(prometheus_adapter)
       end
 
       context 'when environment has no metrics' do
diff --git a/spec/controllers/projects/prometheus/metrics_controller_spec.rb b/spec/controllers/projects/prometheus/metrics_controller_spec.rb
index f17f819feee..b2b245dba90 100644
--- a/spec/controllers/projects/prometheus/metrics_controller_spec.rb
+++ b/spec/controllers/projects/prometheus/metrics_controller_spec.rb
@@ -4,21 +4,22 @@ describe Projects::Prometheus::MetricsController do
   let(:user) { create(:user) }
   let(:project) { create(:project) }
 
-  let(:prometheus_service) { double('prometheus_service') }
+  let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true) }
 
   before do
-    allow(controller).to receive(:project).and_return(project)
-    allow(project).to receive(:find_or_initialize_service).with('prometheus').and_return(prometheus_service)
-
     project.add_master(user)
     sign_in(user)
   end
 
   describe 'GET #active_common' do
+    before do
+      allow(controller).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+    end
+
     context 'when prometheus metrics are enabled' do
       context 'when data is not present' do
         before do
-          allow(prometheus_service).to receive(:matched_metrics).and_return({})
+          allow(prometheus_adapter).to receive(:query).with(:matched_metrics).and_return({})
         end
 
         it 'returns no content response' do
@@ -32,7 +33,7 @@ describe Projects::Prometheus::MetricsController do
         let(:sample_response) { { some_data: 1 } }
 
         before do
-          allow(prometheus_service).to receive(:matched_metrics).and_return(sample_response)
+          allow(prometheus_adapter).to receive(:query).with(:matched_metrics).and_return(sample_response)
         end
 
         it 'returns no content response' do
@@ -53,6 +54,18 @@ describe Projects::Prometheus::MetricsController do
     end
   end
 
+  describe '#prometheus_adapter' do
+    before do
+      allow(controller).to receive(:project).and_return(project)
+    end
+
+    it 'calls prometheus adapter service' do
+      expect_any_instance_of(::Prometheus::AdapterService).to receive(:prometheus_adapter)
+
+      subject.__send__(:prometheus_adapter)
+    end
+  end
+
   def project_params(opts = {})
     opts.reverse_merge(namespace_id: project.namespace, project_id: project)
   end
diff --git a/spec/lib/gitlab/prometheus/queries/additional_metrics_deployment_query_spec.rb b/spec/lib/gitlab/prometheus/queries/additional_metrics_deployment_query_spec.rb
index 0697cb2def6..c7169717fc1 100644
--- a/spec/lib/gitlab/prometheus/queries/additional_metrics_deployment_query_spec.rb
+++ b/spec/lib/gitlab/prometheus/queries/additional_metrics_deployment_query_spec.rb
@@ -7,7 +7,7 @@ describe Gitlab::Prometheus::Queries::AdditionalMetricsDeploymentQuery do
 
   include_examples 'additional metrics query' do
     let(:deployment) { create(:deployment, environment: environment) }
-    let(:query_params) { [environment.id, deployment.id] }
+    let(:query_params) { [deployment.id] }
 
     it 'queries using specific time' do
       expect(client).to receive(:query_range).with(anything,
diff --git a/spec/lib/gitlab/prometheus/queries/deployment_query_spec.rb b/spec/lib/gitlab/prometheus/queries/deployment_query_spec.rb
index 84dc31d9732..ffe3ad85baa 100644
--- a/spec/lib/gitlab/prometheus/queries/deployment_query_spec.rb
+++ b/spec/lib/gitlab/prometheus/queries/deployment_query_spec.rb
@@ -31,7 +31,7 @@ describe Gitlab::Prometheus::Queries::DeploymentQuery do
     expect(client).to receive(:query).with('avg(rate(container_cpu_usage_seconds_total{container_name!="POD",environment="environment-slug"}[30m])) * 100',
                                            time: stop_time)
 
-    expect(subject.query(environment.id, deployment.id)).to eq(memory_values: nil, memory_before: nil, memory_after: nil,
-                                                               cpu_values: nil, cpu_before: nil, cpu_after: nil)
+    expect(subject.query(deployment.id)).to eq(memory_values: nil, memory_before: nil, memory_after: nil,
+                                               cpu_values: nil, cpu_before: nil, cpu_after: nil)
   end
 end
diff --git a/spec/lib/gitlab/prometheus/queries/matched_metrics_query_spec.rb b/spec/lib/gitlab/prometheus/queries/matched_metric_query_spec.rb
index c95719eff1d..420218a695a 100644
--- a/spec/lib/gitlab/prometheus/queries/matched_metrics_query_spec.rb
+++ b/spec/lib/gitlab/prometheus/queries/matched_metric_query_spec.rb
@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe Gitlab::Prometheus::Queries::MatchedMetricsQuery do
+describe Gitlab::Prometheus::Queries::MatchedMetricQuery do
   include Prometheus::MetricBuilders
 
   let(:metric_group_class) { Gitlab::Prometheus::MetricGroup }
diff --git a/spec/models/clusters/applications/prometheus_spec.rb b/spec/models/clusters/applications/prometheus_spec.rb
index df8a508e021..2905b58066b 100644
--- a/spec/models/clusters/applications/prometheus_spec.rb
+++ b/spec/models/clusters/applications/prometheus_spec.rb
@@ -22,11 +22,11 @@ describe Clusters::Applications::Prometheus do
     end
   end
 
-  describe '#proxy_client' do
+  describe '#prometheus_client' do
     context 'cluster is nil' do
       it 'returns nil' do
         expect(subject.cluster).to be_nil
-        expect(subject.proxy_client).to be_nil
+        expect(subject.prometheus_client).to be_nil
       end
     end
 
@@ -35,7 +35,7 @@ describe Clusters::Applications::Prometheus do
       subject { create(:clusters_applications_prometheus, cluster: cluster) }
 
       it 'returns nil' do
-        expect(subject.proxy_client).to be_nil
+        expect(subject.prometheus_client).to be_nil
       end
     end
 
@@ -63,15 +63,15 @@ describe Clusters::Applications::Prometheus do
       end
 
       it 'creates proxy prometheus rest client' do
-        expect(subject.proxy_client).to be_instance_of(RestClient::Resource)
+        expect(subject.prometheus_client).to be_instance_of(RestClient::Resource)
       end
 
       it 'creates proper url' do
-        expect(subject.proxy_client.url).to eq('http://example.com/api/v1/proxy/namespaces/gitlab-managed-apps/service/prometheus-prometheus-server:80')
+        expect(subject.prometheus_client.url).to eq('http://example.com/api/v1/proxy/namespaces/gitlab-managed-apps/service/prometheus-prometheus-server:80')
       end
 
       it 'copies options and headers from kube client to proxy client' do
-        expect(subject.proxy_client.options).to eq(kube_client.rest_client.options.merge(headers: kube_client.headers))
+        expect(subject.prometheus_client.options).to eq(kube_client.rest_client.options.merge(headers: kube_client.headers))
       end
     end
   end
diff --git a/spec/models/concerns/prometheus_adapter_spec.rb b/spec/models/concerns/prometheus_adapter_spec.rb
new file mode 100644
index 00000000000..f4b9c57e71a
--- /dev/null
+++ b/spec/models/concerns/prometheus_adapter_spec.rb
@@ -0,0 +1,121 @@
+require 'spec_helper'
+
+describe PrometheusAdapter, :use_clean_rails_memory_store_caching do
+  include PrometheusHelpers
+  include ReactiveCachingHelpers
+
+  class TestClass
+    include PrometheusAdapter
+  end
+
+  let(:project) { create(:prometheus_project) }
+  let(:service) { project.prometheus_service }
+
+  let(:described_class) { TestClass }
+  let(:environment_query) { Gitlab::Prometheus::Queries::EnvironmentQuery }
+
+  describe '#query' do
+    describe 'environment' do
+      let(:environment) { build_stubbed(:environment, slug: 'env-slug') }
+
+      around do |example|
+        Timecop.freeze { example.run }
+      end
+
+      context 'with valid data' do
+        subject { service.query(:environment, environment) }
+
+        before do
+          stub_reactive_cache(service, prometheus_data, environment_query, environment.id)
+        end
+
+        it 'returns reactive data' do
+          is_expected.to eq(prometheus_metrics_data)
+        end
+      end
+    end
+
+    describe 'matched_metrics' do
+      let(:matched_metrics_query) { Gitlab::Prometheus::Queries::MatchedMetricQuery }
+      let(:prometheus_client_wrapper) { double(:prometheus_client_wrapper, label_values: nil) }
+
+      context 'with valid data' do
+        subject { service.query(:matched_metrics) }
+
+        before do
+          allow(service).to receive(:prometheus_client_wrapper).and_return(prometheus_client_wrapper)
+          synchronous_reactive_cache(service)
+        end
+
+        it 'returns reactive data' do
+          expect(subject[:success]).to be_truthy
+          expect(subject[:data]).to eq([])
+        end
+      end
+    end
+
+    describe 'deployment' do
+      let(:deployment) { build_stubbed(:deployment) }
+      let(:deployment_query) { Gitlab::Prometheus::Queries::DeploymentQuery }
+
+      around do |example|
+        Timecop.freeze { example.run }
+      end
+
+      context 'with valid data' do
+        subject { service.query(:deployment, deployment) }
+
+        before do
+          stub_reactive_cache(service, prometheus_data, deployment_query, deployment.id)
+        end
+
+        it 'returns reactive data' do
+          expect(subject).to eq(prometheus_metrics_data)
+        end
+      end
+    end
+  end
+
+  describe '#calculate_reactive_cache' do
+    let(:environment) { create(:environment, slug: 'env-slug') }
+    before do
+      service.manual_configuration = true
+      service.active = true
+    end
+
+    subject do
+      service.calculate_reactive_cache(environment_query.name, environment.id)
+    end
+
+    around do |example|
+      Timecop.freeze { example.run }
+    end
+
+    context 'when service is inactive' do
+      before do
+        service.active = false
+      end
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'when Prometheus responds with valid data' do
+      before do
+        stub_all_prometheus_requests(environment.slug)
+      end
+
+      it { expect(subject.to_json).to eq(prometheus_data.to_json) }
+      it { expect(subject.to_json).to eq(prometheus_data.to_json) }
+    end
+
+    [404, 500].each do |status|
+      context "when Prometheus responds with #{status}" do
+        before do
+          stub_all_prometheus_requests(environment.slug, status: status, body: "QUERY FAILED!")
+        end
+
+        it { is_expected.to eq(success: false, result: %(#{status} - "QUERY FAILED!")) }
+      end
+    end
+  end
+end
diff --git a/spec/models/deployment_spec.rb b/spec/models/deployment_spec.rb
index ba8aa13d5ad..ac30cd27e0c 100644
--- a/spec/models/deployment_spec.rb
+++ b/spec/models/deployment_spec.rb
@@ -64,6 +64,7 @@ describe Deployment do
 
   describe '#metrics' do
     let(:deployment) { create(:deployment) }
+    let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true) }
 
     subject { deployment.metrics }
 
@@ -76,17 +77,16 @@ describe Deployment do
         {
           success: true,
           metrics: {},
-          last_update: 42,
-          deployment_time: 1494408956
+          last_update: 42
         }
       end
 
       before do
-        allow(deployment.project).to receive_message_chain(:monitoring_service, :deployment_metrics)
-                                       .with(any_args).and_return(simple_metrics)
+        allow(deployment).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+        allow(prometheus_adapter).to receive(:query).with(:deployment, deployment).and_return(simple_metrics)
       end
 
-      it { is_expected.to eq(simple_metrics) }
+      it { is_expected.to eq(simple_metrics.merge({ deployment_time: deployment.created_at.to_i })) }
     end
   end
 
@@ -109,11 +109,11 @@ describe Deployment do
         }
       end
 
-      let(:prometheus_service) { double('prometheus_service') }
+      let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true) }
 
       before do
-        allow(project).to receive(:prometheus_service).and_return(prometheus_service)
-        allow(prometheus_service).to receive(:additional_deployment_metrics).and_return(simple_metrics)
+        allow(deployment).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+        allow(prometheus_adapter).to receive(:query).with(:additional_metrics_deployment, deployment).and_return(simple_metrics)
       end
 
       it { is_expected.to eq(simple_metrics.merge({ deployment_time: deployment.created_at.to_i })) }
diff --git a/spec/models/environment_spec.rb b/spec/models/environment_spec.rb
index 6f24a039998..ceb570ac777 100644
--- a/spec/models/environment_spec.rb
+++ b/spec/models/environment_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Environment do
-  set(:project) { create(:project) }
+  let(:project) { create(:project) }
   subject(:environment) { create(:environment, project: project) }
 
   it { is_expected.to belong_to(:project) }
@@ -452,8 +452,8 @@ describe Environment do
       end
 
       it 'returns the metrics from the deployment service' do
-        expect(project.monitoring_service)
-          .to receive(:environment_metrics).with(environment)
+        expect(environment.prometheus_adapter)
+          .to receive(:query).with(:environment, environment)
           .and_return(:fake_metrics)
 
         is_expected.to eq(:fake_metrics)
@@ -508,12 +508,12 @@ describe Environment do
 
     context 'when the environment has additional metrics' do
       before do
-        allow(environment).to receive(:has_additional_metrics?).and_return(true)
+        allow(environment).to receive(:has_metrics?).and_return(true)
       end
 
       it 'returns the additional metrics from the deployment service' do
-        expect(project.prometheus_service).to receive(:additional_environment_metrics)
-                                                .with(environment)
+        expect(environment.prometheus_adapter).to receive(:query)
+                                                .with(:additional_metrics_environment, environment)
                                                 .and_return(:fake_metrics)
 
         is_expected.to eq(:fake_metrics)
@@ -522,46 +522,13 @@ describe Environment do
 
     context 'when the environment does not have metrics' do
       before do
-        allow(environment).to receive(:has_additional_metrics?).and_return(false)
+        allow(environment).to receive(:has_metrics?).and_return(false)
       end
 
       it { is_expected.to be_nil }
     end
   end
 
-  describe '#has_additional_metrics??' do
-    subject { environment.has_additional_metrics? }
-
-    context 'when the enviroment is available' do
-      context 'with a deployment service' do
-        let(:project) { create(:prometheus_project) }
-
-        context 'and a deployment' do
-          let!(:deployment) { create(:deployment, environment: environment) }
-          it { is_expected.to be_truthy }
-        end
-
-        context 'but no deployments' do
-          it { is_expected.to be_falsy }
-        end
-      end
-
-      context 'without a monitoring service' do
-        it { is_expected.to be_falsy }
-      end
-    end
-
-    context 'when the environment is unavailable' do
-      let(:project) { create(:prometheus_project) }
-
-      before do
-        environment.stop
-      end
-
-      it { is_expected.to be_falsy }
-    end
-  end
-
   describe '#slug' do
     it "is automatically generated" do
       expect(environment.slug).not_to be_nil
@@ -654,4 +621,12 @@ describe Environment do
       end
     end
   end
+
+  describe '#prometheus_adapter' do
+    it 'calls prometheus adapter service' do
+      expect_any_instance_of(Prometheus::AdapterService).to receive(:prometheus_adapter)
+
+      subject.prometheus_adapter
+    end
+  end
 end
diff --git a/spec/models/project_services/prometheus_service_spec.rb b/spec/models/project_services/prometheus_service_spec.rb
index 6693e5783a5..7afb1b4a8e3 100644
--- a/spec/models/project_services/prometheus_service_spec.rb
+++ b/spec/models/project_services/prometheus_service_spec.rb
@@ -6,7 +6,6 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
 
   let(:project) { create(:prometheus_project) }
   let(:service) { project.prometheus_service }
-  let(:environment_query) { Gitlab::Prometheus::Queries::EnvironmentQuery }
 
   describe "Associations" do
     it { is_expected.to belong_to :project }
@@ -55,197 +54,31 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
     end
   end
 
-  describe '#environment_metrics' do
-    let(:environment) { build_stubbed(:environment, slug: 'env-slug') }
-
-    around do |example|
-      Timecop.freeze { example.run }
-    end
-
-    context 'with valid data' do
-      subject { service.environment_metrics(environment) }
-
-      before do
-        stub_reactive_cache(service, prometheus_data, environment_query, environment.id)
-      end
-
-      it 'returns reactive data' do
-        is_expected.to eq(prometheus_metrics_data)
-      end
-    end
-  end
-
-  describe '#matched_metrics' do
-    let(:matched_metrics_query) { Gitlab::Prometheus::Queries::MatchedMetricsQuery }
-    let(:client) { double(:client, label_values: nil) }
-
-    context 'with valid data' do
-      subject { service.matched_metrics }
-
-      before do
-        allow(service).to receive(:client).and_return(client)
-        synchronous_reactive_cache(service)
-      end
-
-      it 'returns reactive data' do
-        expect(subject[:success]).to be_truthy
-        expect(subject[:data]).to eq([])
-      end
-    end
-  end
-
-  describe '#deployment_metrics' do
-    let(:deployment) { build_stubbed(:deployment) }
-    let(:deployment_query) { Gitlab::Prometheus::Queries::DeploymentQuery }
-
-    around do |example|
-      Timecop.freeze { example.run }
-    end
-
-    context 'with valid data' do
-      subject { service.deployment_metrics(deployment) }
-      let(:fake_deployment_time) { 10 }
-
-      before do
-        stub_reactive_cache(service, prometheus_data, deployment_query, deployment.environment.id, deployment.id)
-      end
-
-      it 'returns reactive data' do
-        expect(deployment).to receive(:created_at).and_return(fake_deployment_time)
-
-        expect(subject).to eq(prometheus_metrics_data.merge(deployment_time: fake_deployment_time))
-      end
-    end
-  end
-
-  describe '#calculate_reactive_cache' do
-    let(:environment) { create(:environment, slug: 'env-slug') }
-    before do
-      service.manual_configuration = true
-      service.active = true
-    end
-
-    subject do
-      service.calculate_reactive_cache(environment_query.name, environment.id)
-    end
-
-    around do |example|
-      Timecop.freeze { example.run }
-    end
-
-    context 'when service is inactive' do
-      before do
-        service.active = false
-      end
-
-      it { is_expected.to be_nil }
-    end
-
-    context 'when Prometheus responds with valid data' do
-      before do
-        stub_all_prometheus_requests(environment.slug)
-      end
-
-      it { expect(subject.to_json).to eq(prometheus_data.to_json) }
-      it { expect(subject.to_json).to eq(prometheus_data.to_json) }
-    end
-
-    [404, 500].each do |status|
-      context "when Prometheus responds with #{status}" do
-        before do
-          stub_all_prometheus_requests(environment.slug, status: status, body: "QUERY FAILED!")
-        end
-
-        it { is_expected.to eq(success: false, result: %(#{status} - "QUERY FAILED!")) }
-      end
-    end
-  end
-
-  describe '#client' do
+  describe '#prometheus_client' do
     context 'manual configuration is enabled' do
       let(:api_url) { 'http://some_url' }
+
       before do
+        subject.active = true
         subject.manual_configuration = true
         subject.api_url = api_url
       end
 
-      it 'returns simple rest client from api_url' do
-        expect(subject.client).to be_instance_of(Gitlab::PrometheusClient)
-        expect(subject.client.rest_client.url).to eq(api_url)
+      it 'returns rest client from api_url' do
+        expect(subject.prometheus_client.url).to eq(api_url)
       end
     end
 
     context 'manual configuration is disabled' do
-      let!(:cluster_for_all) { create(:cluster, environment_scope: '*', projects: [project]) }
-      let!(:cluster_for_dev) { create(:cluster, environment_scope: 'dev', projects: [project]) }
-
-      let!(:prometheus_for_dev) { create(:clusters_applications_prometheus, :installed, cluster: cluster_for_dev) }
-      let(:proxy_client) { double('proxy_client') }
+      let(:api_url) { 'http://some_url' }
 
       before do
-        service.manual_configuration = false
-      end
-
-      context 'with cluster for all environments with prometheus installed' do
-        let!(:prometheus_for_all) { create(:clusters_applications_prometheus, :installed, cluster: cluster_for_all) }
-
-        context 'without environment supplied' do
-          it 'returns client handling all environments' do
-            expect(service).to receive(:client_from_cluster).with(cluster_for_all).and_return(proxy_client).twice
-
-            expect(service.client).to be_instance_of(Gitlab::PrometheusClient)
-            expect(service.client.rest_client).to eq(proxy_client)
-          end
-        end
-
-        context 'with dev environment supplied' do
-          let!(:environment) { create(:environment, project: project, name: 'dev') }
-
-          it 'returns dev cluster client' do
-            expect(service).to receive(:client_from_cluster).with(cluster_for_dev).and_return(proxy_client).twice
-
-            expect(service.client(environment.id)).to be_instance_of(Gitlab::PrometheusClient)
-            expect(service.client(environment.id).rest_client).to eq(proxy_client)
-          end
-        end
-
-        context 'with prod environment supplied' do
-          let!(:environment) { create(:environment, project: project, name: 'prod') }
-
-          it 'returns dev cluster client' do
-            expect(service).to receive(:client_from_cluster).with(cluster_for_all).and_return(proxy_client).twice
-
-            expect(service.client(environment.id)).to be_instance_of(Gitlab::PrometheusClient)
-            expect(service.client(environment.id).rest_client).to eq(proxy_client)
-          end
-        end
+        subject.manual_configuration = false
+        subject.api_url = api_url
       end
 
-      context 'with cluster for all environments without prometheus installed' do
-        context 'without environment supplied' do
-          it 'raises PrometheusClient::Error because cluster was not found' do
-            expect { service.client }.to raise_error(Gitlab::PrometheusClient::Error, /couldn't find cluster with Prometheus installed/)
-          end
-        end
-
-        context 'with dev environment supplied' do
-          let!(:environment) { create(:environment, project: project, name: 'dev') }
-
-          it 'returns dev cluster client' do
-            expect(service).to receive(:client_from_cluster).with(cluster_for_dev).and_return(proxy_client).twice
-
-            expect(service.client(environment.id)).to be_instance_of(Gitlab::PrometheusClient)
-            expect(service.client(environment.id).rest_client).to eq(proxy_client)
-          end
-        end
-
-        context 'with prod environment supplied' do
-          let!(:environment) { create(:environment, project: project, name: 'prod') }
-
-          it 'raises PrometheusClient::Error because cluster was not found' do
-            expect { service.client }.to raise_error(Gitlab::PrometheusClient::Error, /couldn't find cluster with Prometheus installed/)
-          end
-        end
+      it 'no client provided' do
+        expect(subject.prometheus_client).to be_nil
       end
     end
   end
@@ -284,7 +117,7 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
     end
   end
 
-  describe '#synchronize_service_state! before_save callback' do
+  describe '#synchronize_service_state before_save callback' do
     context 'no clusters with prometheus are installed' do
       context 'when service is inactive' do
         before do
diff --git a/spec/services/prometheus/adapter_service_spec.rb b/spec/services/prometheus/adapter_service_spec.rb
new file mode 100644
index 00000000000..335fc5844aa
--- /dev/null
+++ b/spec/services/prometheus/adapter_service_spec.rb
@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+describe Prometheus::AdapterService do
+  let(:project) { create(:project) }
+  subject { described_class.new(project) }
+
+  describe '#prometheus_adapter' do
+    let(:cluster) { create(:cluster, :provided_by_user, environment_scope: '*', projects: [project]) }
+
+    context 'prometheus service can execute queries' do
+      let(:prometheus_service) { double(:prometheus_service, can_query?: true) }
+
+      before do
+        allow(project).to receive(:find_or_initialize_service).with('prometheus').and_return prometheus_service
+      end
+
+      it 'return prometheus service as prometheus adapter' do
+        expect(subject.prometheus_adapter).to eq(prometheus_service)
+      end
+    end
+
+    context "prometheus service can't execute queries" do
+      let(:prometheus_service) { double(:prometheus_service, can_query?: false) }
+
+      context 'with cluster with prometheus installed' do
+        let!(:prometheus) { create(:clusters_applications_prometheus, :installed, cluster: cluster) }
+
+        it 'returns application handling all environments' do
+          expect(subject.prometheus_adapter).to eq(prometheus)
+        end
+      end
+
+      context 'with cluster without prometheus installed' do
+        it 'returns nil' do
+          expect(subject.prometheus_adapter).to be_nil
+        end
+      end
+    end
+  end
+end