Revert changes to config/database.yml.postgresql

This is temporary change to ensure
that application works properly
till we start using `main:` everywhere

config/database.yml.postgresql

@@ -2,60 +2,56 @@
 # PRODUCTION
 #
 production:
-  main:
-    adapter: postgresql
-    encoding: unicode
-    database: gitlabhq_production
-    username: git
-    password: "secure password"
-    host: localhost
-    # load_balancing:
-    #   hosts:
-    #     - host1.example.com
-    #     - host2.example.com
-    #   discover:
-    #     nameserver: 1.2.3.4
-    #     port: 8600
-    #     record: secondary.postgresql.service.consul
-    #     interval: 300
+  adapter: postgresql
+  encoding: unicode
+  database: gitlabhq_production
+  username: git
+  password: "secure password"
+  host: localhost
+  # load_balancing:
+  #   hosts:
+  #     - host1.example.com
+  #     - host2.example.com
+  #   discover:
+  #     nameserver: 1.2.3.4
+  #     port: 8600
+  #     record: secondary.postgresql.service.consul
+  #     interval: 300
 
 #
 # Development specific
 #
 development:
-  main:
-    adapter: postgresql
-    encoding: unicode
-    database: gitlabhq_development
-    username: postgres
-    password: "secure password"
-    host: localhost
-    variables:
-      statement_timeout: 15s
+  adapter: postgresql
+  encoding: unicode
+  database: gitlabhq_development
+  username: postgres
+  password: "secure password"
+  host: localhost
+  variables:
+    statement_timeout: 15s
 
 #
 # Staging specific
 #
 staging:
-  main:
-    adapter: postgresql
-    encoding: unicode
-    database: gitlabhq_staging
-    username: git
-    password: "secure password"
-    host: localhost
+  adapter: postgresql
+  encoding: unicode
+  database: gitlabhq_staging
+  username: git
+  password: "secure password"
+  host: localhost
 
 # Warning: The database defined as "test" will be erased and
 # re-generated from your development database when you run "rake".
 # Do not set this db to the same as development or production.
 test: &test
-  main:
-    adapter: postgresql
-    encoding: unicode
-    database: gitlabhq_test
-    username: postgres
-    password:
-    host: localhost
-    prepared_statements: false
-    variables:
-      statement_timeout: 15s
+  adapter: postgresql
+  encoding: unicode
+  database: gitlabhq_test
+  username: postgres
+  password:
+  host: localhost
+  prepared_statements: false
+  variables:
+    statement_timeout: 15s

lib/gitlab/database.rb

@@ -76,7 +76,11 @@ module Gitlab
       # The database is `main` if it is a first entry in `database.yml`
       # Rails internally names them `primary` to avoid confusion
       # with broad `primary` usage we use `main` instead
-      ActiveRecord::Base.configurations.primary?(name.to_s)
+      #
+      # TODO: The explicit `== 'main'` is needed in a transition period till
+      # the `database.yml` is not migrated into `main:` syntax
+      # https://gitlab.com/gitlab-org/gitlab/-/merge_requests/65243
+      ActiveRecord::Base.configurations.primary?(name.to_s) || name.to_s == 'main'
     end
 
     def self.ci_database?(name)

spec/lib/gitlab/database/postgresql_adapter/type_map_cache_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Database::PostgresqlAdapter::TypeMapCache do
-  let(:db_config) { ActiveRecord::Base.configurations.configs_for(env_name: 'test', name: 'main').configuration_hash }
+  let(:db_config) { ActiveRecord::Base.configurations.find_db_config(env_name: 'test').configuration_hash }
   let(:adapter_class) { ActiveRecord::ConnectionAdapters::PostgreSQLAdapter }
 
   before do