Import common metrics into database.

This MR backports PrometheusMetric model to CE
and adds: common, identifier to figure out what kind of metric is used.

1 files changed, 101 insertions, 0 deletions

diff --git a/db/importers/common_metrics_importer.rb b/db/importers/common_metrics_importer.rb
new file mode 100644
index 00000000000..9e6d2dd0518
--- /dev/null
+++ b/db/importers/common_metrics_importer.rb
@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+module Importers
+  class PrometheusMetric < ActiveRecord::Base
+    enum group: {
+      # built-in groups
+      nginx_ingress: -1,
+      ha_proxy: -2,
+      aws_elb: -3,
+      nginx: -4,
+      kubernetes: -5,
+  
+      # custom groups
+      business: 0,
+      response: 1,
+      system: 2,
+    }
+
+    scope :common, -> { where(common: true) }
+
+    GROUP_TITLES = {
+      business: _('Business metrics (Custom)'),
+      response: _('Response metrics (Custom)'),
+      system: _('System metrics (Custom)'),
+      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)')
+    }.freeze
+  end
+
+  class CommonMetricsImporter
+    MissingQueryId = Class.new(StandardError)
+
+    attr_reader :content
+
+    def initialize(file = 'config/prometheus/common_metrics.yml')
+      @content = YAML.load_file(file)
+    end
+    
+    def execute
+      process_content do |id, attributes|
+        find_or_build_metric!(id)
+          .update!(**attributes)
+      end
+    end
+
+    private
+
+    def process_content(&blk)
+      content.map do |group|
+        process_group(group, &blk)
+      end
+    end
+
+    def process_group(group, &blk)
+      attributes = {
+        group: find_group_title_key(group['group'])
+      }
+
+      group['metrics'].map do |metric|
+        process_metric(metric, attributes, &blk)
+      end
+    end
+
+    def process_metric(metric, attributes, &blk)
+      attributes = attributes.merge(
+        title: metric['title'],
+        y_label: metric['y_label'])
+
+      metric['queries'].map do |query|
+        process_metric_query(query, attributes, &blk)
+      end
+    end
+
+    def process_metric_query(query, attributes, &blk)
+      attributes = attributes.merge(
+        legend: query['label'],
+        query: query['query_range'],
+        unit: query['unit'])
+
+      blk.call(query['id'], attributes)
+    end
+
+    def find_or_build_metric!(id)
+      raise MissingQueryId unless id
+    
+      PrometheusMetric.common.find_by(identifier: id) ||
+        PrometheusMetric.new(common: true, identifier: id)
+    end
+
+    def find_group_title_key(title)
+      PrometheusMetric.groups[find_group_title(title)]
+    end
+
+    def find_group_title(title)
+      PrometheusMetric::GROUP_TITLES.invert[title]
+    end
+  end
+end