Add a connection to the pool if there is only one for embedded ansible

[carbonin]

Before #6786 we used to have one connection specified in the connection pool in database.yml

Installations which have been upgraded from before this change still have that one connection pool in place.

The EmbeddedAnsible worker uses a thread rather than a new process so it shares the connection pool with the server. When the pool is set to only contain one connection, the EmbeddedAnsible worker will not be able to start.

This commit adds a connection to the pool in the same way that we do for workers which specify a specific connection pool size in their settings:

manageiq/app/models/miq_worker/runner.rb

Lines 71 to 78 in f6f7120

	def set_connection_pool_size
	cur_size = ActiveRecord::Base.connection_pool.instance_variable_get(:@size)
	new_size = worker_settings[:connection_pool_size] || cur_size
	return if cur_size == new_size
	ActiveRecord::Base.connection_pool.instance_variable_set(:@size, new_size)
	_log.info("#{log_prefix} Changed connection_pool size from #{cur_size} to #{new_size}")
	end

https://bugzilla.redhat.com/show_bug.cgi?id=1484150

[miq-bot]

Checked commit carbonin@a3f50f1 with ruby 2.3.3, rubocop 0.47.1, haml-lint 0.20.0, and yamllint 1.10.0
2 files checked, 0 offenses detected
Everything looks fine. 🍰

[jrafanie]

I savagely approve of this surgical change. It's better than visiting "hunert" appliances.

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit 7429f75c26c6beaeb37150b7d668fad118794865
Author: Joe Rafaniello <jrafanie@users.noreply.github.com>
Date:   Wed Nov 15 09:07:56 2017 -0500

    Merge pull request #16477 from carbonin/alter_connection_pool_for_embedded_ansible
    
    Add a connection to the pool if there is only one for embedded ansible
    (cherry picked from commit 57b5da5bde3227154d4e1173f28cd324ea266b01)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1513631

[simaishi]

Fine backport details:

$ git log -1
commit ff449ade007565cc8f5b3d53667b2e0c6bb94bf4
Author: Joe Rafaniello <jrafanie@users.noreply.github.com>
Date:   Wed Nov 15 09:07:56 2017 -0500

    Merge pull request #16477 from carbonin/alter_connection_pool_for_embedded_ansible
    
    Add a connection to the pool if there is only one for embedded ansible
    (cherry picked from commit 57b5da5bde3227154d4e1173f28cd324ea266b01)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1514139