Add a Prometheus API per environment

The api will proxy requests to the environment's prometheus server.
The Prometheus::ProxyService class can be reused when we add support for
group prometheus servers.

1 files changed, 147 insertions, 0 deletions

diff --git a/spec/controllers/projects/environments/prometheus_api_controller_spec.rb b/spec/controllers/projects/environments/prometheus_api_controller_spec.rb
new file mode 100644
index 00000000000..d943d006ae1
--- /dev/null
+++ b/spec/controllers/projects/environments/prometheus_api_controller_spec.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Projects::Environments::PrometheusApiController do
+  set(:project) { create(:project) }
+  set(:environment) { create(:environment, project: project) }
+  set(:user) { create(:user) }
+
+  before do
+    project.add_reporter(user)
+    sign_in(user)
+  end
+
+  describe 'GET #proxy' do
+    let(:prometheus_proxy_service) { instance_double(Prometheus::ProxyService) }
+    let(:prometheus_response) { { status: :success, body: response_body } }
+    let(:json_response_body) { JSON.parse(response_body) }
+
+    let(:response_body) do
+      "{\"status\":\"success\",\"data\":{\"resultType\":\"scalar\",\"result\":[1553864609.117,\"1\"]}}"
+    end
+
+    before do
+      allow(Prometheus::ProxyService).to receive(:new)
+        .with(environment, 'GET', 'query', anything)
+        .and_return(prometheus_proxy_service)
+
+      allow(prometheus_proxy_service).to receive(:execute)
+        .and_return(prometheus_response)
+    end
+
+    it 'returns prometheus response' do
+      get :proxy, params: environment_params
+
+      expect(response).to have_gitlab_http_status(:ok)
+      expect(json_response).to eq(json_response_body)
+    end
+
+    it 'filters params' do
+      get :proxy, params: environment_params({ extra_param: 'dangerous value' })
+
+      expect(Prometheus::ProxyService).to have_received(:new)
+        .with(environment, 'GET', 'query', ActionController::Parameters.new({ 'query' => '1' }).permit!)
+    end
+
+    context 'Prometheus::ProxyService returns nil' do
+      before do
+        allow(prometheus_proxy_service).to receive(:execute)
+          .and_return(nil)
+      end
+
+      it 'returns 202 accepted' do
+        get :proxy, params: environment_params
+
+        expect(json_response['status']).to eq('processing')
+        expect(json_response['message']).to eq('Not ready yet. Try again later.')
+        expect(response).to have_gitlab_http_status(:accepted)
+      end
+    end
+
+    context 'Prometheus::ProxyService returns status success' do
+      let(:service_response) { { http_status: 404, status: :success, body: '{"body": "value"}' } }
+
+      before do
+        allow(prometheus_proxy_service).to receive(:execute)
+          .and_return(service_response)
+      end
+
+      it 'returns body' do
+        get :proxy, params: environment_params
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['body']).to eq('value')
+      end
+    end
+
+    context 'Prometheus::ProxyService returns status error' do
+      before do
+        allow(prometheus_proxy_service).to receive(:execute)
+          .and_return(service_response)
+      end
+
+      context 'with http_status' do
+        let(:service_response) do
+          { http_status: :service_unavailable, status: :error, message: 'error message' }
+        end
+
+        it 'sets the http response status code' do
+          get :proxy, params: environment_params
+
+          expect(response).to have_gitlab_http_status(:service_unavailable)
+          expect(json_response['status']).to eq('error')
+          expect(json_response['message']).to eq('error message')
+        end
+      end
+
+      context 'without http_status' do
+        let(:service_response) { { status: :error, message: 'error message' } }
+
+        it 'returns message' do
+          get :proxy, params: environment_params
+
+          expect(response).to have_gitlab_http_status(:bad_request)
+          expect(json_response['status']).to eq('error')
+          expect(json_response['message']).to eq('error message')
+        end
+      end
+    end
+
+    context 'with anonymous user' do
+      before do
+        sign_out(user)
+      end
+
+      it 'redirects to signin page' do
+        get :proxy, params: environment_params
+
+        expect(response).to redirect_to(new_user_session_path)
+      end
+    end
+
+    context 'without correct permissions' do
+      before do
+        project.team.truncate
+      end
+
+      it 'returns 404' do
+        get :proxy, params: environment_params
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+  end
+
+  private
+
+  def environment_params(params = {})
+    {
+      id: environment.id,
+      namespace_id: project.namespace,
+      project_id: project,
+      proxy_path: 'query',
+      query: '1'
+    }.merge(params)
+  end
+end