Add support for alert-based metric embeds in GFM

The GFM pipeline supports embeds for various types of metrics.
This adds support for embedding dashboards based on a firing
alert.

changelogs/unreleased/sy-alert-embeds.yml

+---
+title: Add support for alert-based metric embeds in GFM
+merge_request: 25075
+author:
+type: added

ee/lib/banzai/filter/inline_alert_metrics_filter.rb

+# frozen_string_literal: true
+
+module Banzai
+  module Filter
+    # HTML filter that inserts a placeholder element for each
+    # reference to an alert dashboard.
+    class InlineAlertMetricsFilter < ::Banzai::Filter::InlineEmbedsFilter
+      include ::Gitlab::Routing
+
+      # Placeholder element for the frontend to use as an
+      # injection point for charts.
+      def create_element(params)
+        doc.document.create_element(
+          'div',
+          class: 'js-render-metrics',
+          'data-dashboard-url': metrics_dashboard_url(params)
+        )
+      end
+
+      # Search params for selecting alert metrics links. A few
+      # simple checks is enough to boost performance without
+      # the cost of doing a full regex match.
+      def xpath_search
+        "descendant-or-self::a[contains(@href,'metrics_dashboard') and \
+          contains(@href,'prometheus/alerts') and \
+          starts-with(@href, '#{::Gitlab.config.gitlab.url}')]"
+      end
+
+      # Regular expression matching alert dashboard urls
+      def link_pattern
+        ::Gitlab::Metrics::Dashboard::Url.alert_regex
+      end
+
+      private
+
+      # Endpoint FE should hit to collect the appropriate
+      # chart information
+      def metrics_dashboard_url(params)
+        metrics_dashboard_namespace_project_prometheus_alert_url(
+          params['namespace'],
+          params['project'],
+          params['alert'],
+          embedded: true,
+          format: :json,
+          **query_params(params['url'])
+        )
+      end
+
+      # Parses query params out from full url string into hash.
+      #
+      # Ex) 'https://<root>/<project>/metrics_dashboard?title=Title&group=Group'
+      #       --> { title: 'Title', group: 'Group' }
+      def query_params(url)
+        ::Gitlab::Metrics::Dashboard::Url.parse_query(url)
+      end
+    end
+  end
+end

ee/lib/ee/banzai/filter/inline_metrics_redactor_filter.rb

+# frozen_string_literal: true
+
+module EE
+  module Banzai
+    module Filter
+      module InlineMetricsRedactorFilter
+        extend ::Gitlab::Utils::Override
+
+        ROUTE = ::Banzai::Filter::InlineMetricsRedactorFilter::Route
+
+        override :permissions_by_route
+        def permissions_by_route
+          super.concat([
+            ROUTE.new(::Gitlab::Metrics::Dashboard::Url.alert_regex, :read_prometheus_alerts)
+          ])
+        end
+      end
+    end
+  end
+end

ee/lib/ee/banzai/pipeline/gfm_pipeline.rb

@@ -7,6 +7,13 @@ module EE
         extend ActiveSupport::Concern
 
         class_methods do
+          def metrics_filters
+            [
+              ::Banzai::Filter::InlineAlertMetricsFilter,
+              *super
+            ]
+          end
+
           def reference_filters
             [
               ::Banzai::Filter::EpicReferenceFilter,

ee/spec/features/markdown/metrics_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Metrics rendering', :js, :use_clean_rails_memory_store_caching, :sidekiq_inline do
+  include PrometheusHelpers
+  include MetricsDashboardUrlHelpers
+
+  let_it_be(:user) { create(:user) }
+  let_it_be(:project) { create(:prometheus_project) }
+
+  let(:issue) { create(:issue, project: project, description: description) }
+
+  before do
+    clear_host_from_memoized_variables
+
+    allow(::Gitlab.config.gitlab)
+      .to receive(:url)
+      .and_return(urls.root_url.chomp('/'))
+
+    stub_licensed_features(prometheus_alerts: true)
+
+    project.add_maintainer(user)
+    sign_in(user)
+
+    import_common_metrics
+    stub_any_prometheus_request_with_response
+  end
+
+  after do
+    clear_host_from_memoized_variables
+  end
+
+  # This context block can be moved as-is to inside the
+  # 'internal metrics embeds' block in spec/features/markdown/metrics_spec.rb
+  # while migrating alerting to CE. Add `:alert_regex` to
+  # clear_host_from_memoized_variables
+  context 'for GitLab-managed alerting rules' do
+    let(:metric) { PrometheusMetric.last }
+    let!(:alert) { create(:prometheus_alert, project: project, prometheus_metric: metric) }
+
+    let(:description) { "# Summary \n[](#{metrics_url})" }
+    let(:metrics_url) do
+      urls.metrics_dashboard_project_prometheus_alert_url(
+        project,
+        metric.id,
+        environment_id: alert.environment_id,
+        embedded: true
+      )
+    end
+
+    it 'shows embedded metrics' do
+      visit project_issue_path(project, issue)
+
+      expect(page).to have_css('div.prometheus-graph')
+      expect(page).to have_text(metric.title)
+      expect(page).to have_text(metric.y_label)
+      expect(page).not_to have_text(metrics_url)
+    end
+  end
+
+  def import_common_metrics
+    ::Gitlab::DatabaseImporters::CommonMetrics::Importer.new.execute
+  end
+end

ee/spec/lib/banzai/filter/inline_alert_metrics_filter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Banzai::Filter::InlineAlertMetricsFilter do
+  include FilterSpecHelper
+
+  let(:params) { ['foo', 'bar', 12] }
+  let(:query_params) { {} }
+
+  let(:trigger_url) { urls.metrics_dashboard_namespace_project_prometheus_alert_url(*params, query_params) }
+  let(:dashboard_url) { urls.metrics_dashboard_namespace_project_prometheus_alert_url(*params, **query_params, embedded: true, format: :json) }
+
+  it_behaves_like 'a metrics embed filter'
+
+  context 'with query params specified' do
+    let(:query_params) { { timestamp: 'yesterday' } }
+
+    it_behaves_like 'a metrics embed filter'
+  end
+end

ee/spec/lib/banzai/filter/inline_metrics_redactor_filter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Banzai::Filter::InlineMetricsRedactorFilter do
+  include FilterSpecHelper
+
+  let_it_be(:project) { create(:project) }
+  let(:input) { %(<div class="js-render-metrics" data-dashboard-url="#{url}"></div>) }
+  let(:doc) { filter(input) }
+
+  context 'for an alert embed' do
+    let_it_be(:alert) { create(:prometheus_alert, project: project) }
+    let(:url) do
+      urls.metrics_dashboard_project_prometheus_alert_url(
+        project,
+        alert.prometheus_metric_id,
+        environment_id: alert.environment_id,
+        embedded: true
+      )
+    end
+
+    before do
+      stub_licensed_features(prometheus_alerts: true)
+    end
+
+    it_behaves_like 'redacts the embed placeholder'
+    it_behaves_like 'retains the embed placeholder when applicable'
+  end
+end

lib/banzai/filter/inline_metrics_redactor_filter.rb

@@ -143,3 +143,5 @@ module Banzai
     end
   end
 end
+
+Banzai::Filter::InlineMetricsRedactorFilter.prepend_if_ee('EE::Banzai::Filter::InlineMetricsRedactorFilter')

spec/features/markdown/metrics_spec.rb

@@ -2,25 +2,32 @@
 
 require 'spec_helper'
 
-describe 'Metrics rendering', :js, :use_clean_rails_memory_store_caching, :sidekiq_might_not_need_inline do
+describe 'Metrics rendering', :js, :use_clean_rails_memory_store_caching, :sidekiq_inline do
   include PrometheusHelpers
   include GrafanaApiHelpers
+  include MetricsDashboardUrlHelpers
+
+  let_it_be(:user) { create(:user) }
+  let_it_be(:project) { create(:prometheus_project) }
+  let_it_be(:environment) { create(:environment, project: project) }
 
-  let(:user) { create(:user) }
-  let(:project) { create(:prometheus_project) }
-  let(:environment) { create(:environment, project: project) }
   let(:issue) { create(:issue, project: project, description: description) }
   let(:description) { "See [metrics dashboard](#{metrics_url}) for info." }
-  let(:metrics_url) { metrics_project_environment_url(project, environment) }
+  let(:metrics_url) { urls.metrics_project_environment_url(project, environment) }
 
   before do
-    configure_host
+    clear_host_from_memoized_variables
+
+    allow(::Gitlab.config.gitlab)
+      .to receive(:url)
+      .and_return(urls.root_url.chomp('/'))
+
     project.add_developer(user)
     sign_in(user)
   end
 
   after do
-    restore_host
+    clear_host_from_memoized_variables
   end
 
   context 'internal metrics embeds' do
@@ -38,7 +45,7 @@ describe 'Metrics rendering', :js, :use_clean_rails_memory_store_caching, :sidek
     end
 
     context 'when dashboard params are in included the url' do
-      let(:metrics_url) { metrics_project_environment_url(project, environment, **chart_params) }
+      let(:metrics_url) { urls.metrics_project_environment_url(project, environment, **chart_params) }
 
       let(:chart_params) do
         {
@@ -81,32 +88,4 @@ describe 'Metrics rendering', :js, :use_clean_rails_memory_store_caching, :sidek
   def import_common_metrics
     ::Gitlab::DatabaseImporters::CommonMetrics::Importer.new.execute
   end
-
-  def configure_host
-    @original_default_host = default_url_options[:host]
-    @original_gitlab_url = Gitlab.config.gitlab[:url]
-
-    # Ensure we create a metrics url with the right host.
-    # Configure host for route helpers in specs (also updates root_url):
-    default_url_options[:host] = Capybara.server_host
-
-    # Ensure we identify urls with the appropriate host.
-    # Configure host to include port in app:
-    Gitlab.config.gitlab[:url] = root_url.chomp('/')
-
-    clear_host_from_memoized_variables
-  end
-
-  def restore_host
-    default_url_options[:host] = @original_default_host
-    Gitlab.config.gitlab[:url] = @original_gitlab_url
-
-    clear_host_from_memoized_variables
-  end
-
-  def clear_host_from_memoized_variables
-    [:metrics_regex, :grafana_regex].each do |method_name|
-      Gitlab::Metrics::Dashboard::Url.clear_memoization(method_name)
-    end
-  end
 end

spec/support/helpers/metrics_dashboard_url_helpers.rb

+# frozen_string_literal: true
+
+module MetricsDashboardUrlHelpers
+  # Using the url_helpers available in the test suite uses
+  # the sample host, but the urls generated may need to
+  # point to the configured host in the :js trait
+  def urls
+    ::Gitlab::Routing.url_helpers
+  end
+
+  def clear_host_from_memoized_variables
+    [:metrics_regex, :grafana_regex, :cluster_metrics, :alerts_regex].each do |method_name|
+      Gitlab::Metrics::Dashboard::Url.clear_memoization(method_name)
+    end
+  end
+end