Move importers to lib folder

This moves our metric importers into the lib folder. This will allow
them to be autoloaded instead of having to explicitly require them.

4 files changed, 142 insertions, 0 deletions

diff --git a/lib/gitlab/importers/common_metrics.rb b/lib/gitlab/importers/common_metrics.rb
new file mode 100644
index 00000000000..210ae6cb14a
--- /dev/null
+++ b/lib/gitlab/importers/common_metrics.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Importers
+    module CommonMetrics
+    end
+  end
+end
+
+Gitlab::Importers::CommonMetrics.prepend(EE::Gitlab::Importers::CommonMetrics)
diff --git a/lib/gitlab/importers/common_metrics/importer.rb b/lib/gitlab/importers/common_metrics/importer.rb
new file mode 100644
index 00000000000..c916af58820
--- /dev/null
+++ b/lib/gitlab/importers/common_metrics/importer.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Importers
+    module CommonMetrics
+      class Importer
+        MissingQueryId = Class.new(StandardError)
+
+        attr_reader :content
+
+        def initialize(filename = 'common_metrics.yml')
+          @content = YAML.load_file(Rails.root.join('config', 'prometheus', filename))
+        end
+
+        def execute
+          PrometheusMetric.reset_column_information
+
+          process_content do |id, attributes|
+            find_or_build_metric!(id)
+              .update!(**attributes)
+          end
+        end
+
+        private
+
+        def process_content(&blk)
+          content['panel_groups'].map do |group|
+            process_group(group, &blk)
+          end
+        end
+
+        def process_group(group, &blk)
+          attributes = {
+            group: find_group_title_key(group['group'])
+          }
+
+          group['panels'].map do |panel|
+            process_panel(panel, attributes, &blk)
+          end
+        end
+
+        def process_panel(panel, attributes, &blk)
+          attributes = attributes.merge(
+            title: panel['title'],
+            y_label: panel['y_label'])
+
+          panel['metrics'].map do |metric_details|
+            process_metric_details(metric_details, attributes, &blk)
+          end
+        end
+
+        def process_metric_details(metric_details, attributes, &blk)
+          attributes = attributes.merge(
+            legend: metric_details['label'],
+            query: metric_details['query_range'],
+            unit: metric_details['unit'])
+
+          yield(metric_details['id'], attributes)
+        end
+
+        # rubocop: disable CodeReuse/ActiveRecord
+        def find_or_build_metric!(id)
+          raise MissingQueryId unless id
+
+          PrometheusMetric.common.find_by(identifier: id) ||
+            PrometheusMetric.new(common: true, identifier: id)
+        end
+        # rubocop: enable CodeReuse/ActiveRecord
+
+        def find_group_title_key(title)
+          PrometheusMetricEnums.groups[find_group_title(title)]
+        end
+
+        def find_group_title(title)
+          PrometheusMetricEnums.group_titles.invert[title]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/importers/common_metrics/prometheus_metric.rb b/lib/gitlab/importers/common_metrics/prometheus_metric.rb
new file mode 100644
index 00000000000..a9397f4c055
--- /dev/null
+++ b/lib/gitlab/importers/common_metrics/prometheus_metric.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Importers
+    module CommonMetrics
+      class PrometheusMetric < ApplicationRecord
+        enum group: PrometheusMetricEnums.groups
+        scope :common, -> { where(common: true) }
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/importers/common_metrics/prometheus_metric_enums.rb b/lib/gitlab/importers/common_metrics/prometheus_metric_enums.rb
new file mode 100644
index 00000000000..dbf4c9e9b55
--- /dev/null
+++ b/lib/gitlab/importers/common_metrics/prometheus_metric_enums.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Importers
+    module CommonMetrics
+      module PrometheusMetricEnums
+        def self.groups
+          {
+            # built-in groups
+            nginx_ingress_vts: -1,
+            ha_proxy: -2,
+            aws_elb: -3,
+            nginx: -4,
+            kubernetes: -5,
+            nginx_ingress: -6,
+
+            # custom groups
+            business: 0,
+            response: 1,
+            system: 2
+          }
+        end
+
+        def self.group_titles
+          {
+            business: _('Business metrics (Custom)'),
+            response: _('Response metrics (Custom)'),
+            system: _('System metrics (Custom)'),
+            nginx_ingress_vts: _('Response metrics (NGINX Ingress VTS)'),
+            nginx_ingress: _('Response metrics (NGINX Ingress)'),
+            ha_proxy: _('Response metrics (HA Proxy)'),
+            aws_elb: _('Response metrics (AWS ELB)'),
+            nginx: _('Response metrics (NGINX)'),
+            kubernetes: _('System metrics (Kubernetes)')
+          }
+        end
+      end
+    end
+  end
+end