MiqSshUtil updates

[djberg96]

This PR fixes a bug in the MiqSshUtil#exec method, and makes a few tweaks to the constructor and exec method in general.

Fixes:

Error handling is currently semi-busted. The on_extended_data hook is missing a yield param. The net result is that there is never any data in the error output. In addition, the status check could break since it defaults to nil, with the result that it will try to call .zero? on a nil object, which will raise an exception. So, I changed the default from nil to 0.

Updates:

• Some unused code that was commented out was removed, i.e. logging.
• Some workaround code for older versions of net-ssh that is no longer relevant was removed.
• You can now configure the use_agent option. It still defaults to false for backwards compatibility.
• The error handling was updated slightly. It now no longer relies on activesupport methods, and checks the error buffer, too.

You can see these issues in practice with this simple script:

# Assuming you're in the manageiq-gems-pending repo
$:.unshift('lib/gems/pending/util')
require 'MiqSshUtil'
require 'etc'

# Adjust as desired
hostname = 'localhost'
username = Etc.getlogin
password = 'xxxxxxx'
command  = 'bogus'

pubkey = IO.read(File.join(Dir.home, '.ssh', 'id_rsa.pub'))

# You will have to edit MiqSshUtil.rb if you're on master and need 'use_agent'.
opts = {
  :key_data => pubkey,
  :use_agent => true
}

ssh = MiqSshUtil.new(hostname, username, password)

begin
  result = ssh.exec(command)
rescue => err
  puts "OOPS: #{err.message}"
else
  puts "RESULT: #{result}"
end

BEFORE:

RESULT: <---- Blank! And not registered as an error!

AFTER:

OOPS: MiqSshUtil::exec - Command 'bogus' failed: bash: bogus: command not found, status: 127

Partially addresses https://bugzilla.redhat.com/show_bug.cgi?id=1719689

[miq-bot]

Checked commit https://github.com/djberg96/manageiq-gems-pending/commit/c950fa8fede20a014dcc9b3bc885978adbdababd with ruby 2.3.3, rubocop 0.69.0, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 1 offense detected

lib/gems/pending/util/MiqSshUtil.rb

• ❗ - Line 144, Col 13 - Layout/EmptyLineAfterGuardClause - Add empty line after guard clause.

[djberg96]

@roliveri How's it look?

[djberg96]

@miq-bot add_reviewer @bdunne

[djberg96]

@miq-bot add_label bug, changelog/yes

[djberg96]

@miq-bot add_label hammer/yes

[djberg96]

@carbonin Alright, I've added some specs that should demonstrate that it behaves as expected. I didn't want to go down this road originally because I knew it would mean making a couple other refactorings.

Namely, the Channel#exec block had to be moved up (so that channel failure could be checked before command failure), and I had to strip the signal check result because it can (apparently) return a blank string of more than 1 character.

[Fryguy]

LGTM, but leaving the final merge to @carbonin

[simaishi]

Hammer backport details:

$ git log -1
commit 7300bf53e17784a7c12dc1133239bc8b76a61f8a
Author: Jason Frey <jfrey@redhat.com>
Date:   Tue Jul 2 16:16:08 2019 -0400

    Merge pull request #437 from djberg96/miq_ssh_util_updates
    
    MiqSshUtil updates
    
    (cherry picked from commit 02c9fb67797331640e2840682d8234f2f4a5415c)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1726439