Merge branch 'db_load_balancing_service_discovery_srv' into 'master'

DB Load Balancing: Support SRV lookups

See merge request gitlab-org/gitlab-ce!32135

doc/administration/database_load_balancing.md

@@ -122,6 +122,7 @@ production:
     discover:
       nameserver: localhost
       record: secondary.postgresql.service.consul
+      record_type: A
       port: 8600
       interval: 60
       disconnect_timeout: 120
@@ -137,12 +138,16 @@ The following options can be set:
 | Option               | Description                                                                                       | Default   |
 |----------------------|---------------------------------------------------------------------------------------------------|-----------|
 | `nameserver`         | The nameserver to use for looking up the DNS record.                                              | localhost |
-| `record`             | The A record to look up. This option is required for service discovery to work.                   |           |
+| `record`             | The record to look up. This option is required for service discovery to work.                     |           |
+| `record_type`        | Optional record type to look up, this can be either A or SRV (since GitLab 12.3)                  | A         |
 | `port`               | The port of the nameserver.                                                                       | 8600      |
 | `interval`           | The minimum time in seconds between checking the DNS record.                                      | 60        |
 | `disconnect_timeout` | The time in seconds after which an old connection is closed, after the list of hosts was updated. | 120       |
 | `use_tcp`            | Lookup DNS resources using TCP instead of UDP                                                     | false     |
 
+If `record_type` is set to `SRV`, GitLab will continue to use a round-robin algorithm
+and will ignore the `weight` and `priority` in the record.
+
 The `interval` value specifies the _minimum_ time between checks. If the A
 record has a TTL greater than this value, then service discovery will honor said
 TTL. For example, if the TTL of the A record is 90 seconds, then service

lib/gitlab/database.rb

@@ -195,13 +195,14 @@ module Gitlab
 
     # pool_size - The size of the DB pool.
     # host - An optional host name to use instead of the default one.
-    def self.create_connection_pool(pool_size, host = nil)
+    def self.create_connection_pool(pool_size, host = nil, port = nil)
       # See activerecord-4.2.7.1/lib/active_record/connection_adapters/connection_specification.rb
       env = Rails.env
       original_config = ActiveRecord::Base.configurations
 
       env_config = original_config[env].merge('pool' => pool_size)
       env_config['host'] = host if host
+      env_config['port'] = port if port
 
       config = original_config.merge(env => env_config)
 

spec/lib/gitlab/database_spec.rb

@@ -347,6 +347,17 @@ describe Gitlab::Database do
         pool.disconnect!
       end
     end
+
+    it 'allows setting of a custom hostname and port' do
+      pool = described_class.create_connection_pool(5, '127.0.0.1', 5432)
+
+      begin
+        expect(pool.spec.config[:host]).to eq('127.0.0.1')
+        expect(pool.spec.config[:port]).to eq(5432)
+      ensure
+        pool.disconnect!
+      end
+    end
   end
 
   describe '.cached_column_exists?' do