(PUP-11787) Warn if we fail to serialize and fallback

If puppetserver falls back to PSON when serializing a catalog, then conversion
of rich data will be lossy, but the problem won't be noticed until the catalog
is applied on the agent.

This converts the debug message to a warning to assist troubleshooting. This
affects both `find` and `search` operations for all indirected types.

Author: joshcooper

lib/puppet/network/http/api/indirected_routes.rb

@@ -124,7 +124,7 @@ def do_find(indirection, key, params, request, response)
 
     rendered_result = result
 
-    rendered_format = first_response_formatter_for(indirection.model, request) do |format|
+    rendered_format = first_response_formatter_for(indirection.model, request, key) do |format|
       if result.respond_to?(:render)
         Puppet::Util::Profiler.profile(_("Rendered result in %{format}") % { format: format }, [:http, :v3_render, format]) do
           rendered_result = result.render(format)
@@ -157,7 +157,7 @@ def do_search(indirection, key, params, request, response)
 
     rendered_result = nil
 
-    rendered_format = first_response_formatter_for(indirection.model, request) do |format|
+    rendered_format = first_response_formatter_for(indirection.model, request, key) do |format|
       rendered_result = indirection.model.render_multiple(format, result)
     end
 
@@ -185,14 +185,15 @@ def do_save(indirection, key, params, request, response)
 
   # Return the first response formatter that didn't cause the yielded
   # block to raise a FormatError.
-  def first_response_formatter_for(model, request, &block)
+  def first_response_formatter_for(model, request, key, &block)
     formats = accepted_response_formatters_for(model, request)
     formatter = formats.find do |format|
       begin
         yield format
         true
       rescue Puppet::Network::FormatHandler::FormatError => err
-        Puppet.log_exception(err, err.message, level: :debug)
+        Puppet.warning(_("Failed to serialize %{model} for '%{key}': %{detail}") %
+          {model: model, key: key, detail: err})
         false
       end
     end

spec/unit/network/http/api/indirected_routes_spec.rb

@@ -182,6 +182,7 @@
       indirection.save(data, "my data")
       request = a_request_that_finds(data, :accept_header => "application/json, text/pson")
       allow(data).to receive(:to_json).and_raise(Puppet::Network::FormatHandler::FormatError, 'Could not render to Puppet::Network::Format[json]: source sequence is illegal/malformed utf-8')
+      expect(Puppet).to receive(:warning).with(/Failed to serialize Puppet::IndirectorTesting for 'my data': Could not render to Puppet::Network::Format\[json\]/)
 
       handler.call(request, response)
 
@@ -228,6 +229,7 @@
       indirection.save(data, "my data")
       request = a_request_that_searches(Puppet::IndirectorTesting.new("my"), :accept_header => "application/json, text/pson")
       allow(data).to receive(:to_json).and_raise(Puppet::Network::FormatHandler::FormatError, 'Could not render to Puppet::Network::Format[json]: source sequence is illegal/malformed utf-8')
+      expect(Puppet).to receive(:warning).with(/Failed to serialize Puppet::IndirectorTesting for 'my': Could not render_multiple to Puppet::Network::Format\[json\]/)
 
       handler.call(request, response)