Added Prometheus Service and Prometheus graphs

app/assets/javascripts/dispatcher.js

+import PrometheusGraph from './monitoring/prometheus_graph'; // TODO: Maybe Make this a bundle
 /* eslint-disable func-names, space-before-function-paren, no-var, prefer-arrow-callback, wrap-iife, no-shadow, consistent-return, one-var, one-var-declaration-per-line, camelcase, default-case, no-new, quotes, no-duplicate-case, no-case-declarations, no-fallthrough, max-len */
 /* global UsernameValidator */
 /* global ActiveTabMemoizer */
@@ -297,6 +298,8 @@ const UserCallout = require('./user_callout');
         case 'ci:lints:show':
           new gl.CILintEditor();
           break;
+        case 'projects:environments:metrics':
+          new PrometheusGraph();
         case 'users:show':
           new UserCallout();
           break;

app/assets/stylesheets/pages/environments.scss

@@ -143,3 +143,71 @@
     }
   }
 }
+
+.prometheus-graph {
+  text {
+    fill: $stat-graph-axis-fill;
+  }
+}
+
+.x-axis path,
+.y-axis path,
+.label-x-axis-line,
+.label-y-axis-line {
+  fill: none;
+  stroke-width: 1;
+  shape-rendering: crispEdges;
+}
+
+.x-axis path,
+.y-axis path {
+  stroke: $stat-graph-axis-fill;
+}
+
+.label-x-axis-line,
+.label-y-axis-line {
+  stroke: $border-color;
+}
+
+.y-axis {
+  line {
+    stroke: $stat-graph-axis-fill;
+    stroke-width: 1;
+  }
+}
+
+.metric-area {
+  opacity: 0.8;
+}
+
+.prometheus-graph-overlay {
+  fill: none;
+  opacity: 0.0;
+  pointer-events: all;
+}
+
+.rect-text-metric {
+  fill: $white-light;
+  stroke-width: 1;
+  stroke: $black;
+}
+
+.rect-axis-text {
+  fill: $white-light;
+}
+
+.text-metric,
+.text-median-metric,
+.text-metric-usage,
+.text-metric-date {
+  fill: $black;
+}
+
+.text-metric-date {
+  font-weight: 200;
+}
+
+.selected-metric-line {
+  stroke: $black;
+  stroke-width: 1;
+}

app/controllers/projects/environments_controller.rb

@@ -5,7 +5,7 @@ class Projects::EnvironmentsController < Projects::ApplicationController
   before_action :authorize_create_deployment!, only: [:stop]
   before_action :authorize_update_environment!, only: [:edit, :update]
   before_action :authorize_admin_environment!, only: [:terminal, :terminal_websocket_authorize]
-  before_action :environment, only: [:show, :edit, :update, :stop, :terminal, :terminal_websocket_authorize]
+  before_action :environment, only: [:show, :edit, :update, :stop, :terminal, :terminal_websocket_authorize, :metrics]
   before_action :verify_api_request!, only: :terminal_websocket_authorize
 
   def index
@@ -109,6 +109,19 @@ class Projects::EnvironmentsController < Projects::ApplicationController
     end
   end
 
+  def metrics
+    # Currently, this acts as a hint to load the metrics details into the cache
+    # if they aren't there already
+    @metrics = environment.metrics || {}
+
+    respond_to do |format|
+      format.html
+      format.json do
+        render json: @metrics, status: @metrics.any? ? :ok : :no_content
+      end
+    end
+  end
+
   private
 
   def verify_api_request!

app/helpers/gitlab_routing_helper.rb

@@ -74,6 +74,10 @@ module GitlabRoutingHelper
     namespace_project_environment_path(environment.project.namespace, environment.project, environment, *args)
   end
 
+  def environment_metrics_path(environment, *args)
+    metrics_namespace_project_environment_path(environment.project.namespace, environment.project, environment, *args)
+  end
+
   def issue_path(entity, *args)
     namespace_project_issue_path(entity.project.namespace, entity.project, entity, *args)
   end

app/models/environment.rb

@@ -145,6 +145,14 @@ class Environment < ActiveRecord::Base
     project.deployment_service.terminals(self) if has_terminals?
   end
 
+  def has_metrics?
+    project.monitoring_service.present? && available? && last_deployment.present?
+  end
+
+  def metrics
+    project.monitoring_service.metrics(self) if has_metrics?
+  end
+
   # An environment name is not necessarily suitable for use in URLs, DNS
   # or other third-party contexts, so provide a slugified version. A slug has
   # the following properties:

app/models/project.rb

@@ -113,6 +113,7 @@ class Project < ActiveRecord::Base
   has_one :gitlab_issue_tracker_service, dependent: :destroy, inverse_of: :project
   has_one :external_wiki_service, dependent: :destroy
   has_one :kubernetes_service, dependent: :destroy, inverse_of: :project
+  has_one :prometheus_service, dependent: :destroy, inverse_of: :project
   has_one :mock_ci_service, dependent: :destroy
 
   has_one  :forked_project_link,  dependent: :destroy, foreign_key: "forked_to_project_id"
@@ -771,6 +772,14 @@ class Project < ActiveRecord::Base
     @deployment_service ||= deployment_services.reorder(nil).find_by(active: true)
   end
 
+  def monitoring_services
+    services.where(category: :monitoring)
+  end
+
+  def monitoring_service
+    @monitoring_service ||= monitoring_services.reorder(nil).find_by(active: true)
+  end
+
   def jira_tracker?
     issues_tracker.to_param == 'jira'
   end

app/models/project_services/monitoring_service.rb

+# Base class for monitoring services
+#
+# These services integrate with a deployment solution like Prometheus
+# to provide additional features for environments.
+class MonitoringService < Service
+  default_value_for :category, 'monitoring'
+
+  def self.supported_events
+    %w()
+  end
+
+  # Environments have a number of metrics
+  def metrics(environment)
+    raise NotImplementedError
+  end
+end

app/models/project_services/prometheus_service.rb

+class PrometheusService < MonitoringService
+  include ReactiveCaching
+
+  self.reactive_cache_key = ->(service) { [service.class.model_name.singular, service.project_id] }
+  self.reactive_cache_lease_timeout = 30.seconds
+  self.reactive_cache_refresh_interval = 30.seconds
+  self.reactive_cache_lifetime = 1.minute
+
+  #  Access to prometheus is directly through the API
+  prop_accessor :api_url
+
+  with_options presence: true, if: :activated? do
+    validates :api_url, url: true
+  end
+
+  after_save :clear_reactive_cache!
+
+  def initialize_properties
+    if properties.nil?
+      self.properties = {}
+    end
+  end
+
+  def title
+    'Prometheus'
+  end
+
+  def description
+    'Prometheus monitoring'
+  end
+
+  def help
+    'Retrieves `container_cpu_usage_seconds_total` and `container_memory_usage_bytes` from the configured Prometheus server. An `environment` label is required on each metric to identify the Environment.'
+  end
+
+  def self.to_param
+    'prometheus'
+  end
+
+  def fields
+    [
+      {
+        type: 'text',
+        name: 'api_url',
+        title: 'API URL',
+        placeholder: 'Prometheus API Base URL, like http://prometheus.example.com/'
+      }
+    ]
+  end
+
+  # Check we can connect to the Prometheus API
+  def test(*args)
+    client.ping
+
+    { success: true, result: 'Checked API endpoint' }
+  rescue Gitlab::PrometheusError => err
+    { success: false, result: err }
+  end
+
+  def metrics(environment)
+    with_reactive_cache(environment.slug) do |data|
+      data
+    end
+  end
+
+  # Cache metrics for specific environment
+  def calculate_reactive_cache(environment_slug)
+    return unless active? && project && !project.pending_delete?
+
+    memory_query = %{sum(container_memory_usage_bytes{container_name="app",environment="#{environment_slug}"})/1024/1024}
+    cpu_query = %{sum(rate(container_cpu_usage_seconds_total{container_name="app",environment="#{environment_slug}"}[2m]))}
+
+    {
+      success: true,
+      metrics: {
+        # Memory used in MB
+        memory_values: client.query_range(memory_query, start: 8.hours.ago),
+        memory_current: client.query(memory_query),
+        # CPU Usage rate in cores.
+        cpu_values: client.query_range(cpu_query, start: 8.hours.ago),
+        cpu_current: client.query(cpu_query)
+      },
+      last_update: Time.now.utc
+    }
+
+  rescue Gitlab::PrometheusError => err
+    { success: false, result: err.message }
+  end
+
+  def client
+    @prometheus ||= Gitlab::Prometheus.new(api_url: api_url)
+  end
+end

app/models/service.rb

@@ -232,6 +232,7 @@ class Service < ActiveRecord::Base
       mattermost
       pipelines_email
       pivotaltracker
+      prometheus
       pushover
       redmine
       slack_slash_commands

app/views/projects/environments/_metrics_button.html.haml

+- environment = local_assigns.fetch(:environment)
+
+- return unless environment.has_metrics? && can?(current_user, :read_environment, environment)
+
+= link_to environment_metrics_path(environment), title: 'See metrics', class: 'btn metrics-button' do
+  = icon('area-chart')

app/views/projects/environments/metrics.html.haml

+- @no_container = true
+- page_title "Metrics for environment", @environment.name
+= render "projects/pipelines/head"
+
+%div{ class: container_class }
+  .top-area
+    .row
+      .col-sm-6
+        %h3.page-title
+          Environment:
+          = @environment.name
+
+      .col-sm-6
+        .nav-controls
+          = render 'projects/deployments/actions', deployment: @environment.last_deployment
+  .row
+    .col-sm-12
+      %svg.prometheus-graph{ 'graph-type' => 'cpu_values' }
+  .row
+    .col-sm-12
+      %svg.prometheus-graph{ 'graph-type' => 'memory_values' }

app/views/projects/environments/show.html.haml

@@ -8,6 +8,7 @@
       %h3.page-title= @environment.name
     .col-md-3
       .nav-controls
+        = render 'projects/environments/metrics_button', environment: @environment
         = render 'projects/environments/terminal_button', environment: @environment
         = render 'projects/environments/external_url', environment: @environment
         - if can?(current_user, :update_environment, @environment)

config/routes/project.rb

@@ -159,6 +159,7 @@ constraints(ProjectUrlConstrainer.new) do
         member do
           post :stop
           get :terminal
+          get :metrics
           get '/terminal.ws/authorize', to: 'environments#terminal_websocket_authorize', constraints: { format: nil }
         end
 

lib/api/services.rb

@@ -422,6 +422,14 @@ module API
           desc: 'Comma-separated list of branches which will be automatically inspected. Leave blank to include all branches.'
         }
       ],
+      'prometheus' => [
+        {
+          required: true,
+          name: :api_url,
+          type: String,
+          desc: 'Prometheus API Base URL, like http://prometheus.example.com/'
+        }
+      ],
       'pushover' => [
         {
           required: true,
@@ -558,6 +566,7 @@ module API
       SlackSlashCommandsService,
       PipelinesEmailService,
       PivotaltrackerService,
+      PrometheusService,
       PushoverService,
       RedmineService,
       SlackService,

lib/gitlab/prometheus.rb

+module Gitlab
+  PrometheusError = Class.new(StandardError)
+
+  # Helper methods to interact with Prometheus network services & resources
+  class Prometheus
+    attr_reader :api_url
+
+    def initialize(api_url:)
+      @api_url = api_url
+    end
+
+    def ping
+      json_api_get('query', query: '1')
+    end
+
+    def query(query)
+      get_result('vector') do
+        json_api_get('query', query: query)
+      end
+    end
+
+    def query_range(query, start: 8.hours.ago)
+      get_result('matrix') do
+        json_api_get('query_range',
+          query: query,
+          start: start.to_f,
+          end: Time.now.utc.to_f,
+          step: 1.minute.to_i)
+      end
+    end
+
+    private
+
+    def json_api_get(type, args = {})
+      get(join_api_url(type, args))
+    rescue Errno::ECONNREFUSED
+      raise PrometheusError, 'Connection refused'
+    end
+
+    def join_api_url(type, args = {})
+      url = URI.parse(api_url)
+    rescue URI::Error
+      raise PrometheusError, "Invalid API URL: #{api_url}"
+    else
+      url.path = [url.path.sub(%r{/+\z}, ''), 'api', 'v1', type].join('/')
+      url.query = args.to_query
+
+      url.to_s
+    end
+
+    def get(url)
+      handle_response(HTTParty.get(url))
+    end
+
+    def handle_response(response)
+      if response.code == 200 && response['status'] == 'success'
+        response['data'] || {}
+      elsif response.code == 400
+        raise PrometheusError, response['error'] || 'Bad data received'
+      else
+        raise PrometheusError, "#{response.code} - #{response.body}"
+      end
+    end
+
+    def get_result(expected_type)
+      data = yield
+      data['result'] if data['resultType'] == expected_type
+    end
+  end
+end

spec/controllers/projects/environments_controller_spec.rb

@@ -187,6 +187,52 @@ describe Projects::EnvironmentsController do
     end
   end
 
+  describe 'GET #metrics' do
+    before do
+      allow(controller).to receive(:environment).and_return(environment)
+    end
+
+    context 'when environment has no metrics' do
+      before do
+        expect(environment).to receive(:metrics).and_return(nil)
+      end
+
+      it 'returns a metrics page' do
+        get :metrics, environment_params
+
+        expect(response).to be_ok
+      end
+
+      context 'when requesting metrics as JSON' do
+        it 'returns a metrics JSON document' do
+          get :metrics, environment_params(format: :json)
+
+          expect(response).to have_http_status(204)
+          expect(json_response).to eq({})
+        end
+      end
+    end
+
+    context 'when environment has some metrics' do
+      before do
+        expect(environment).to receive(:metrics).and_return({
+          success: true,
+          metrics: {},
+          last_update: 42
+        })
+      end
+
+      it 'returns a metrics JSON document' do
+        get :metrics, environment_params(format: :json)
+
+        expect(response).to be_ok
+        expect(json_response['success']).to be(true)
+        expect(json_response['metrics']).to eq({})
+        expect(json_response['last_update']).to eq(42)
+      end
+    end
+  end
+
   def environment_params(opts = {})
     opts.reverse_merge(namespace_id: project.namespace,
                        project_id: project,

spec/factories/projects.rb

@@ -195,4 +195,15 @@ FactoryGirl.define do
   factory :kubernetes_project, parent: :empty_project do
     kubernetes_service
   end
+
+  factory :prometheus_project, parent: :empty_project do
+    after :create do |project|
+      project.create_prometheus_service(
+        active: true,
+        properties: {
+          api_url: 'https://prometheus.example.com'
+        }
+      )
+    end
+  end
 end

spec/features/projects/environments/environment_metrics_spec.rb

+require 'spec_helper'
+
+feature 'Environment > Metrics', :feature do
+  include PrometheusHelpers
+
+  given(:user) { create(:user) }
+  given(:project) { create(:prometheus_project) }
+  given(:pipeline) { create(:ci_pipeline, project: project) }
+  given(:build) { create(:ci_build, pipeline: pipeline) }
+  given(:environment) { create(:environment, project: project) }
+  given(:current_time) { Time.now.utc }
+
+  background do
+    project.add_developer(user)
+    create(:deployment, environment: environment, deployable: build)
+    stub_all_prometheus_requests(environment.slug)
+
+    login_as(user)
+    visit_environment(environment)
+  end
+
+  around do |example|
+    Timecop.freeze(current_time) { example.run }
+  end
+
+  context 'with deployments and related deployable present' do
+    scenario 'shows metrics' do
+      click_link('See metrics')
+
+      expect(page).to have_css('svg.prometheus-graph')
+    end
+  end
+
+  def visit_environment(environment)
+    visit namespace_project_environment_path(environment.project.namespace,
+                                             environment.project,
+                                             environment)
+  end
+end

spec/features/environment_spec.rb → spec/features/projects/environments/environment_spec.rb

@@ -37,13 +37,7 @@ feature 'Environment', :feature do
 
         scenario 'does show deployment SHA' do
           expect(page).to have_link(deployment.short_sha)
-        end
-
-        scenario 'does not show a re-deploy button for deployment without build' do
           expect(page).not_to have_link('Re-deploy')
-        end
-
-        scenario 'does not show terminal button' do
           expect(page).not_to have_terminal_button
         end
       end
@@ -58,13 +52,7 @@ feature 'Environment', :feature do
 
         scenario 'does show build name' do
           expect(page).to have_link("#{build.name} (##{build.id})")
-        end
-
-        scenario 'does show re-deploy button' do
           expect(page).to have_link('Re-deploy')
-        end
-
-        scenario 'does not show terminal button' do
           expect(page).not_to have_terminal_button
         end
 
@@ -117,9 +105,6 @@ feature 'Environment', :feature do
 
                 it 'displays a web terminal' do
                   expect(page).to have_selector('#terminal')
-                end
-
-                it 'displays a link to the environment external url' do
                   expect(page).to have_link(nil, href: environment.external_url)
                 end
               end
@@ -147,10 +132,6 @@ feature 'Environment', :feature do
                                     on_stop: 'close_app')
               end
 
-              scenario 'does show stop button' do
-                expect(page).to have_link('Stop')
-              end
-
               scenario 'does allow to stop environment' do
                 click_link('Stop')
 

spec/javascripts/fixtures/environments/metrics.html.haml

+%div
+  .top-area
+    .row
+      .col-sm-6
+        %h3.page-title
+          Metrics for environment
+  .row
+    .col-sm-12
+      %svg.prometheus-graph{ 'graph-type' => 'cpu_values' }
+  .row
+    .col-sm-12
+      %svg.prometheus-graph{ 'graph-type' => 'memory_values' }
\ No newline at end of file

spec/javascripts/monitoring/prometheus_graph_spec.js

+import 'jquery';
+import es6Promise from 'es6-promise';
+import '~/lib/utils/common_utils';
+import PrometheusGraph from '~/monitoring/prometheus_graph';
+import { prometheusMockData } from './prometheus_mock_data';
+
+es6Promise.polyfill();
+
+describe('PrometheusGraph', () => {
+  const fixtureName = 'static/environments/metrics.html.raw';
+  const prometheusGraphContainer = '.prometheus-graph';
+  const prometheusGraphContents = `${prometheusGraphContainer}[graph-type=cpu_values]`;
+
+  preloadFixtures(fixtureName);
+
+  beforeEach(() => {
+    loadFixtures(fixtureName);
+    this.prometheusGraph = new PrometheusGraph();
+    const self = this;
+    const fakeInit = (metricsResponse) => {
+      self.prometheusGraph.transformData(metricsResponse);
+      self.prometheusGraph.createGraph();
+    };
+    spyOn(this.prometheusGraph, 'init').and.callFake(fakeInit);
+  });
+
+  it('initializes graph properties', () => {
+    // Test for the measurements
+    expect(this.prometheusGraph.margin).toBeDefined();
+    expect(this.prometheusGraph.marginLabelContainer).toBeDefined();
+    expect(this.prometheusGraph.originalWidth).toBeDefined();
+    expect(this.prometheusGraph.originalHeight).toBeDefined();
+    expect(this.prometheusGraph.height).toBeDefined();
+    expect(this.prometheusGraph.width).toBeDefined();
+    expect(this.prometheusGraph.backOffRequestCounter).toBeDefined();
+    // Test for the graph properties (colors, radius, etc.)
+    expect(this.prometheusGraph.graphSpecificProperties).toBeDefined();
+    expect(this.prometheusGraph.commonGraphProperties).toBeDefined();
+  });
+
+  it('transforms the data', () => {
+    this.prometheusGraph.init(prometheusMockData.metrics);
+    expect(this.prometheusGraph.data).toBeDefined();
+    expect(this.prometheusGraph.data.cpu_values.length).toBe(121);
+    expect(this.prometheusGraph.data.memory_values.length).toBe(121);
+  });
+
+  it('creates two graphs', () => {
+    this.prometheusGraph.init(prometheusMockData.metrics);
+    expect($(prometheusGraphContainer).length).toBe(2);
+  });
+
+  describe('Graph contents', () => {
+    beforeEach(() => {
+      this.prometheusGraph.init(prometheusMockData.metrics);
+    });
+
+    it('has axis, an area, a line and a overlay', () => {
+      const $graphContainer = $(prometheusGraphContents).find('.x-axis').parent();
+      expect($graphContainer.find('.x-axis')).toBeDefined();
+      expect($graphContainer.find('.y-axis')).toBeDefined();
+      expect($graphContainer.find('.prometheus-graph-overlay')).toBeDefined();
+      expect($graphContainer.find('.metric-line')).toBeDefined();
+      expect($graphContainer.find('.metric-area')).toBeDefined();
+    });
+
+    it('has legends, labels and an extra axis that labels the metrics', () => {
+      const $prometheusGraphContents = $(prometheusGraphContents);
+      const $axisLabelContainer = $(prometheusGraphContents).find('.label-x-axis-line').parent();
+      expect($prometheusGraphContents.find('.label-x-axis-line')).toBeDefined();
+      expect($prometheusGraphContents.find('.label-y-axis-line')).toBeDefined();
+      expect($prometheusGraphContents.find('.label-axis-text')).toBeDefined();
+      expect($prometheusGraphContents.find('.rect-axis-text')).toBeDefined();
+      expect($axisLabelContainer.find('rect').length).toBe(2);
+      expect($axisLabelContainer.find('text').length).toBe(4);
+    });
+  });
+});

spec/lib/gitlab/import_export/all_models.yml

@@ -136,6 +136,7 @@ project:
 - slack_slash_commands_service
 - irker_service
 - pivotaltracker_service
+- prometheus_service
 - hipchat_service
 - flowdock_service
 - assembla_service

spec/lib/gitlab/prometheus_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Prometheus, lib: true do
+  include PrometheusHelpers
+
+  subject { described_class.new(api_url: 'https://prometheus.example.com') }
+
+  describe '#ping' do
+    it 'issues a "query" request to the API endpoint' do
+      req_stub = stub_prometheus_request(prometheus_query_url('1'), body: prometheus_value_body('vector'))
+
+      expect(subject.ping).to eq({ "resultType" => "vector", "result" => [{ "metric" => {}, "value" => [1488772511.004, "0.000041021495238095323"] }] })
+      expect(req_stub).to have_been_requested
+    end
+  end
+
+  # This shared examples expect:
+  # - query_url: A query URL
+  # - execute_query: A query call
+  shared_examples 'failure response' do
+    context 'when request returns 400 with an error message' do
+      it 'raises a Gitlab::PrometheusError error' do
+        req_stub = stub_prometheus_request(query_url, status: 400, body: { error: 'bar!' })
+
+        expect { execute_query }
+          .to raise_error(Gitlab::PrometheusError, 'bar!')
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns 400 without an error message' do
+      it 'raises a Gitlab::PrometheusError error' do
+        req_stub = stub_prometheus_request(query_url, status: 400)
+
+        expect { execute_query }
+          .to raise_error(Gitlab::PrometheusError, 'Bad data received')
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns 500' do
+      it 'raises a Gitlab::PrometheusError error' do
+        req_stub = stub_prometheus_request(query_url, status: 500, body: { message: 'FAIL!' })
+
+        expect { execute_query }
+          .to raise_error(Gitlab::PrometheusError, '500 - {"message":"FAIL!"}')
+        expect(req_stub).to have_been_requested
+      end
+    end
+  end
+
+  describe '#query' do
+    let(:prometheus_query) { prometheus_cpu_query('env-slug') }
+    let(:query_url) { prometheus_query_url(prometheus_query) }
+
+    context 'when request returns vector results' do
+      it 'returns data from the API call' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_value_body('vector'))
+
+        expect(subject.query(prometheus_query)).to eq [{ "metric" => {}, "value" => [1488772511.004, "0.000041021495238095323"] }]
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns matrix results' do
+      it 'returns nil' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_value_body('matrix'))
+
+        expect(subject.query(prometheus_query)).to be_nil
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns no data' do
+      it 'returns []' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_empty_body('vector'))
+
+        expect(subject.query(prometheus_query)).to be_empty
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    it_behaves_like 'failure response' do
+      let(:execute_query) { subject.query(prometheus_query) }
+    end
+  end
+
+  describe '#query_range' do
+    let(:prometheus_query) { prometheus_memory_query('env-slug') }
+    let(:query_url) { prometheus_query_range_url(prometheus_query) }
+
+    around do |example|
+      Timecop.freeze { example.run }
+    end
+
+    context 'when a start time is passed' do
+      let(:query_url) { prometheus_query_range_url(prometheus_query, start: 2.hours.ago) }
+
+      it 'passed it in the requested URL' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_values_body('vector'))
+
+        subject.query_range(prometheus_query, start: 2.hours.ago)
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns vector results' do
+      it 'returns nil' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_values_body('vector'))
+
+        expect(subject.query_range(prometheus_query)).to be_nil
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns matrix results' do
+      it 'returns data from the API call' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_values_body('matrix'))
+
+        expect(subject.query_range(prometheus_query)).to eq([
+          {
+            "metric" => {},
+            "values" => [[1488758662.506, "0.00002996364761904785"], [1488758722.506, "0.00003090239047619091"]]
+          }
+        ])
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'when request returns no data' do
+      it 'returns []' do
+        req_stub = stub_prometheus_request(query_url, body: prometheus_empty_body('matrix'))
+
+        expect(subject.query_range(prometheus_query)).to be_empty
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    it_behaves_like 'failure response' do
+      let(:execute_query) { subject.query_range(prometheus_query) }
+    end
+  end
+end

spec/models/environment_spec.rb

@@ -271,7 +271,11 @@ describe Environment, models: true do
 
     context 'when the environment is unavailable' do
       let(:project) { create(:kubernetes_project) }
-      before { environment.stop }
+
+      before do
+        environment.stop
+      end
+
       it { is_expected.to be_falsy }
     end
   end
@@ -281,20 +285,85 @@ describe Environment, models: true do
     subject { environment.terminals }
 
     context 'when the environment has terminals' do
-      before { allow(environment).to receive(:has_terminals?).and_return(true) }
+      before do
+        allow(environment).to receive(:has_terminals?).and_return(true)
+      end
 
       it 'returns the terminals from the deployment service' do
-        expect(project.deployment_service).
-          to receive(:terminals).with(environment).
-          and_return(:fake_terminals)
+        expect(project.deployment_service)
+          .to receive(:terminals).with(environment)
+          .and_return(:fake_terminals)
 
         is_expected.to eq(:fake_terminals)
       end
     end
 
     context 'when the environment does not have terminals' do
-      before { allow(environment).to receive(:has_terminals?).and_return(false) }
-      it { is_expected.to eq(nil) }
+      before do
+        allow(environment).to receive(:has_terminals?).and_return(false)
+      end
+
+      it { is_expected.to be_nil }
+    end
+  end
+
+  describe '#has_metrics?' do
+    subject { environment.has_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 '#metrics' do
+    let(:project) { create(:prometheus_project) }
+    subject { environment.metrics }
+
+    context 'when the environment has metrics' do
+      before do
+        allow(environment).to receive(:has_metrics?).and_return(true)
+      end
+
+      it 'returns the metrics from the deployment service' do
+        expect(project.monitoring_service)
+          .to receive(:metrics).with(environment)
+          .and_return(:fake_metrics)
+
+        is_expected.to eq(:fake_metrics)
+      end
+    end
+
+    context 'when the environment does not have metrics' do
+      before do
+        allow(environment).to receive(:has_metrics?).and_return(false)
+      end
+
+      it { is_expected.to be_nil }
     end
   end
 

spec/models/project_services/prometheus_service_spec.rb

+require 'spec_helper'
+
+describe PrometheusService, models: true, caching: true do
+  include PrometheusHelpers
+  include ReactiveCachingHelpers
+
+  let(:project) { create(:prometheus_project) }
+  let(:service) { project.prometheus_service }
+
+  describe "Associations" do
+    it { is_expected.to belong_to :project }
+  end
+
+  describe 'Validations' do
+    context 'when service is active' do
+      before { subject.active = true }
+
+      it { is_expected.to validate_presence_of(:api_url) }
+    end
+
+    context 'when service is inactive' do
+      before { subject.active = false }
+
+      it { is_expected.not_to validate_presence_of(:api_url) }
+    end
+  end
+
+  describe '#test' do
+    let!(:req_stub) { stub_prometheus_request(prometheus_query_url('1'), body: prometheus_value_body('vector')) }
+
+    context 'success' do
+      it 'reads the discovery endpoint' do
+        expect(service.test[:success]).to be_truthy
+        expect(req_stub).to have_been_requested
+      end
+    end
+
+    context 'failure' do
+      let!(:req_stub) { stub_prometheus_request(prometheus_query_url('1'), status: 404) }
+
+      it 'fails to read the discovery endpoint' do
+        expect(service.test[:success]).to be_falsy
+        expect(req_stub).to have_been_requested
+      end
+    end
+  end
+
+  describe '#metrics' do
+    let(:environment) { build_stubbed(:environment, slug: 'env-slug') }
+    subject { service.metrics(environment) }
+
+    around do |example|
+      Timecop.freeze { example.run }
+    end
+
+    context 'with valid data' do
+      before do
+        stub_reactive_cache(service, prometheus_data, 'env-slug')
+      end
+
+      it 'returns reactive data' do
+        is_expected.to eq(prometheus_data)
+      end
+    end
+  end
+
+  describe '#calculate_reactive_cache' do
+    let(:environment) { build_stubbed(:environment, slug: 'env-slug') }
+
+    around do |example|
+      Timecop.freeze { example.run }
+    end
+
+    subject do
+      service.calculate_reactive_cache(environment.slug)
+    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) }
+    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

spec/requests/api/v3/services_spec.rb

@@ -6,7 +6,9 @@ describe API::V3::Services, api: true  do
   let(:user) { create(:user) }
   let(:project) { create(:empty_project, creator_id: user.id, namespace: user.namespace) }
 
-  Service.available_services_names.each do |service|
+  available_services = Service.available_services_names
+  available_services.delete('prometheus')
+  available_services.each do |service|
     describe "DELETE /projects/:id/services/#{service.dasherize}" do
       include_context service
 

spec/support/prometheus_helpers.rb

+module PrometheusHelpers
+  def prometheus_memory_query(environment_slug)
+    %{sum(container_memory_usage_bytes{container_name="app",environment="#{environment_slug}"})/1024/1024}
+  end
+
+  def prometheus_cpu_query(environment_slug)
+    %{sum(rate(container_cpu_usage_seconds_total{container_name="app",environment="#{environment_slug}"}[2m]))}
+  end
+
+  def prometheus_query_url(prometheus_query)
+    query = { query: prometheus_query }.to_query
+
+    "https://prometheus.example.com/api/v1/query?#{query}"
+  end
+
+  def prometheus_query_range_url(prometheus_query, start: 8.hours.ago)
+    query = {
+      query: prometheus_query,
+      start: start.to_f,
+      end: Time.now.utc.to_f,
+      step: 1.minute.to_i
+    }.to_query
+
+    "https://prometheus.example.com/api/v1/query_range?#{query}"
+  end
+
+  def stub_prometheus_request(url, body: {}, status: 200)
+    WebMock.stub_request(:get, url)
+      .to_return({
+        status: status,
+        headers: { 'Content-Type' => 'application/json' },
+        body: body.to_json
+      })
+  end
+
+  def stub_all_prometheus_requests(environment_slug, body: nil, status: 200)
+    stub_prometheus_request(
+      prometheus_query_url(prometheus_memory_query(environment_slug)),
+      status: status,
+      body: body || prometheus_value_body
+    )
+    stub_prometheus_request(
+      prometheus_query_range_url(prometheus_memory_query(environment_slug)),
+      status: status,
+      body: body || prometheus_values_body
+    )
+    stub_prometheus_request(
+      prometheus_query_url(prometheus_cpu_query(environment_slug)),
+      status: status,
+      body: body || prometheus_value_body
+    )
+    stub_prometheus_request(
+      prometheus_query_range_url(prometheus_cpu_query(environment_slug)),
+      status: status,
+      body: body || prometheus_values_body
+    )
+  end
+
+  def prometheus_data(last_update: Time.now.utc)
+    {
+      success: true,
+      metrics: {
+        memory_values: prometheus_values_body('matrix').dig(:data, :result),
+        memory_current: prometheus_value_body('vector').dig(:data, :result),
+        cpu_values: prometheus_values_body('matrix').dig(:data, :result),
+        cpu_current: prometheus_value_body('vector').dig(:data, :result)
+      },
+      last_update: last_update
+    }
+  end
+
+  def prometheus_empty_body(type)
+    {
+      "status": "success",
+      "data": {
+        "resultType": type,
+        "result": []
+      }
+    }
+  end
+
+  def prometheus_value_body(type = 'vector')
+    {
+      "status": "success",
+      "data": {
+        "resultType": type,
+        "result": [
+          {
+            "metric": {},
+            "value": [
+              1488772511.004,
+              "0.000041021495238095323"
+            ]
+          }
+        ]
+      }
+    }
+  end
+
+  def prometheus_values_body(type = 'matrix')
+    {
+      "status": "success",
+      "data": {
+        "resultType": type,
+        "result": [
+          {
+            "metric": {},
+            "values": [
+              [1488758662.506, "0.00002996364761904785"],
+              [1488758722.506, "0.00003090239047619091"]
+            ]
+          }
+        ]
+      }
+    }
+  end
+end