Improve difference reporting in debug log

Use Case

As reported in slack, the resource API's debug output could be more helpful when applying changes. Here's the original report:

[1] pry(#<Puppet::Provider::CalicoGlobalNetworkPolicy::CalicoGlobalNetworkPolicy>)> continue                                                                                                [34/38693]
Debug: Current State: {:name=>"web", :order=>10, :ingress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{"nets"=>["10.0.2.0/24"]}, "destination"=>{"ports"=>[443]}}], :egress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{}, "destination"=>{"nets"=>["0.0.0.0/0"]}}], :selector=>"app == \"web\"", :types=>["Ingress", "Egress"], :pre_dnat=>false, :apply_on_forward=>false, :ensure=>"present"}                                                                                                                                                                                                   Notice: /Stage[main]/Main/Node[default]/Calico_global_network_policy[web]/ingress: ingress changed [
  {
    'action' => 'Allow',
    'protocol' => 'TCP',
    'source' => {
      'nets' => ['10.0.2.0/24']
    },
    'destination' => {
      'ports' => [443]
    }
  }] to [
  {
    'action' => 'Allow',
    'protocol' => 'TCP',
    'source' => {
      'nets' => ['10.0.2.0/24']
    },
    'destination' => {
      'ports' => ['443']
    }
  }]
Debug: Target State: {:name=>"web", :types=>["Ingress", "Egress"], :selector=>"app == \"web\"", :ingress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{"nets"=>["10.0.2.0/24"]}, "destination"=> {"ports"=>["443"]}}], :egress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{}, "destination"=>{"nets"=>["0.0.0.0/0"]}}], :order=>10, :ensure=>"present", :pre_dnat=>false, :apply_on_forward=>false}
Debug: calico_global_network_policy[web]: Updating: Start
Notice: calico_global_network_policy[web]: Updating: Updating 'web' with {:name=>"web", :types=>["Ingress", "Egress"], :selector=>"app == \"web\"", :ingress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{"nets"=>["10.0.2.0/24"]}, "destination"=>{"ports"=>["443"]}}], :egress=>[{"action"=>"Allow", "protocol"=>"TCP", "source"=>{}, "destination"=>{"nets"=>["0.0.0.0/0"]}}], :order=>10, :ensure=>"present", :pre_dnat=>false, :apply_on_forward=>false}
Debug: Executing: '/usr/local/bin/calicoctl patch globalnetworkpolicy web -p '{"spec":{"order":10,"ingress":[{"action":"Allow","protocol":"TCP","source":{"nets":["10.0.2.0/24"]},"destination":{"ports":["443"]}}],"egress":[{"action":"Allow","protocol":"TCP","source":{},"destination":{"nets":["0.0.0.0/0"]}}],"selector":"app == \"web\"","types":["Ingress","Egress"],"preDNAT":false,"applyOnForward":false}}''
Notice: calico_global_network_policy[web]: Updating: Finished in 0.033700 seconds

Try finding why above is triggering a change without looking at the solution below.

Describe the Solution You Would Like

Around

https://github.com/puppetlabs/puppet-resource_api/blob/bd93dbac616baa4ffa18c99a0b45946c9d474fec/lib/puppet/resource_api.rb#L330-L334

implement a debug-optional diff on the full data structures in @rsapi_current_state vs target_state using a similar technique as rspec's matchers:

  expected: {"action"=>"Allow", "destination"=>{"ports"=>["443"]}, "protocol"=>"TCP", "source"=>{"nets"=>["10.0.2.0/24"]}}
      got: {"action"=>"Allow", "destination"=>{"ports"=>[443]}, "protocol"=>"TCP", "source"=>{"nets"=>["10.0.2.0/24"]}}

  (compared using ==)

  Diff:
  @@ -1,5 +1,5 @@
   "action" => "Allow",
  -"destination" => {"ports"=>["443"]},
  +"destination" => {"ports"=>[443]},
   "protocol" => "TCP",
   "source" => {"nets"=>["10.0.2.0/24"]},

produced by

it {
  expect({
    'action' => 'Allow',
    'protocol' => 'TCP',
    'source' => {
      'nets' => ['10.0.2.0/24']
    },
    'destination' => {
      'ports' => [443]
    }
  }).to eq({
    'action' => 'Allow',
    'protocol' => 'TCP',
    'source' => {
      'nets' => ['10.0.2.0/24']
    },
    'destination' => {
      'ports' => ['443']
    }
  })
}

Start in lib/puppet/resource_api.rb around lines 330-334, where @rsapi_current_state is compared with target_state. Review the requested RSpec-style expected, got, and diff output and determine how it should be enabled for debug logging. Done means differing nested structures produce a focused diff instead of only the broad change report.