Merge branch 'alloy_db_usage_ping' into 'master'

Add AlloyDB support to DB usage ping

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/98601



Merged-by: Aleksei Lipniagov <alipniagov@gitlab.com>
Approved-by: Manoj M J <mmj@gitlab.com>
Approved-by: Krasimir Angelov <kangelov@gitlab.com>
Approved-by: Aleksei Lipniagov <alipniagov@gitlab.com>
Co-authored-by: Jon Jenkins <jjenkins@gitlab.com>

config/metrics/settings/20211201012652_flavor.yml

@@ -3,7 +3,7 @@ key_path: database.flavor
 description: What PostgreSQL flavor is being used. Possible values are
   "Amazon Aurora PostgreSQL", "PostgreSQL on Amazon RDS", "Cloud SQL for PostgreSQL",
   "Azure Database for PostgreSQL - Single Server", "Azure Database for PostgreSQL - Flexible Server",
-  or "null".
+  "AlloyDB for PostgreSQL", or "null".
 product_section: enablement
 product_stage: enablement
 product_group: database

lib/gitlab/database/reflection.rb

@@ -124,7 +124,11 @@ def flavor
           #   - https://docs.microsoft.com/en-us/azure/postgresql/flexible-server/concepts-servers
           #   - https://docs.microsoft.com/en-us/azure/postgresql/concepts-servers#managing-your-server
           # this database is present on both Flexible and Single server, so we should check the former first.
-          'Azure Database for PostgreSQL - Single Server' => { statement: "SELECT datname FROM pg_database WHERE datname = 'azure_maintenance'" }
+          'Azure Database for PostgreSQL - Single Server' => { statement: "SELECT datname FROM pg_database WHERE datname = 'azure_maintenance'" },
+          # Based on
+          #   - https://cloud.google.com/sql/docs/postgres/flags
+          # running a query to detect flag names that begin with 'alloydb
+          'AlloyDB for PostgreSQL' => { statement: "SELECT name FROM pg_settings WHERE name LIKE 'alloydb%'" }
         }.each do |flavor, conditions|
           return flavor if connection.execute(conditions[:statement]).to_a.present?
         rescue ActiveRecord::StatementInvalid => e

spec/lib/gitlab/database/reflection_spec.rb

@@ -314,6 +314,12 @@ def stub_statements(statements)
       expect(database.flavor).to eq('Azure Database for PostgreSQL - Single Server')
     end
 
+    it 'recognizes AlloyDB for PostgreSQL' do
+      stub_statements("SELECT name FROM pg_settings WHERE name LIKE 'alloydb%'")
+
+      expect(database.flavor).to eq('AlloyDB for PostgreSQL')
+    end
+
     it 'returns nil if can not recognize the flavor' do
       expect(database.flavor).to be_nil
     end