Rails Postgres reconnection on failover for RDS

Question

I have a Rails application with a Postgres database under AWS RDS with multi-az architecture. The HA architecture used by RDS is master/slave and they provide the service with a single endpoint that points to the current master.

Whenever there's a database failover, Active Record will continue to try to connect to the same server, instead of retrying the connection in order to pick up the new IP for the master.

Is there a way to create a "global" rescue for the ActiveRecord::StatementInvalid: PG::ConnectionBad: PQsocket() can't get socket descriptor error that simply runs ActiveRecord::Base.connection_pool.disconnect! that will make the next query to work?

Answer 1

Using a monkey patch to postgres_adapter, I was able to reconnect the Active Record.

lib/core_ext/active_record/postgresql_adapter.rb:

require 'active_record/connection_adapters/postgresql_adapter'

 

class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

  private

  def exec_no_cache(sql, name, binds)

    log(sql, name, binds) { @connection.async_exec(sql, []) }

  rescue ActiveRecord::StatementInvalid => e

    if e.to_s.include?('PG::ConnectionBad')

      ActiveRecord::Base.connection_pool.disconnect!

    end

    raise e

  end

end