Use custom output to break long log lines. Force encoding.

lib/vagrant/shared_helpers.rb

@@ -236,14 +236,15 @@ module Vagrant
   def self.enable_server_mode!
     if !server_mode?
       SERVER_MODE_CALLBACKS.each(&:call)
-      Log4r::Outputter.stderr.formatter = Util::HCLogFormatter.new
+      Util::HCLogOutputter.new("hclog")
+      Log4r::Outputter["hclog"].formatter = Util::HCLogFormatter.new
       Log4r::Logger.each_logger do |l|
-        l.outputters = Log4r::Outputter.stderr if l.parent == Log4r::RootLogger.instance
+        l.outputters = Log4r::Outputter["hclog"] if l.parent == Log4r::RootLogger.instance
       end
       Log4r::Logger::Repository.class_eval do
         def self.[]=(n, l)
           self.synchronize do
-            l.outputters = Log4r::Outputter.stderr if l.parent == Log4r::RootLogger.instance
+            l.outputters = Log4r::Outputter["hclog"] if l.parent == Log4r::RootLogger.instance
             instance.loggers[n] = l
           end
         end

lib/vagrant/util.rb

@@ -19,6 +19,7 @@ module Vagrant
     autoload :GuestInspection,           'vagrant/util/guest_inspection'
     autoload :HashWithIndifferentAccess, 'vagrant/util/hash_with_indifferent_access'
     autoload :HCLogFormatter,            'vagrant/util/logging_formatter'
+    autoload :HCLogOutputter,            'vagrant/util/logging_formatter'
     autoload :InstallShellConfig,        'vagrant/util/install_cli_autocomplete'
     autoload :InstallZSHShellConfig,     'vagrant/util/install_cli_autocomplete'
     autoload :InstallBashShellConfig,    'vagrant/util/install_cli_autocomplete'

lib/vagrant/util/logging_formatter.rb

@@ -27,18 +27,34 @@ module Vagrant
 
     class HCLogFormatter < Log4r::BasicFormatter
       def format(event)
-        d = {
-          "@timestamp" => Time.now.strftime("%Y-%m-%dT%H:%M:%S.%6N%:z"),
-          "@level" => Log4r::LNAMES[event.level].downcase,
-          "@module" => event.fullname.gsub("::", "."),
-          "@message" => format_object(event.data),
-        }
-        d["@caller"] = event.tracer[0] if event.tracer
+        message = format_object(event.data).
+          force_encoding('UTF-8').
+          scrub("?")
+        if message.count("\n") > 40
+          message = message.split("\n").each_slice(40).to_a
+          message = [message.shift.join("\n")] + message.map { |m|
+            "continued...\n" + m.join("\n") }
+        else
+          message = [message]
+        end
 
-        # TODO(spox): fix this with force encoding on the message
-        begin
+        message.map do |msg|
+          d = {
+            "@timestamp" => Time.now.strftime("%Y-%m-%dT%H:%M:%S.%6N%:z"),
+            "@level" => Log4r::LNAMES[event.level].downcase,
+            "@module" => event.fullname.gsub("::", "."),
+            "@message" => msg,
+          }
+          d["@caller"] = event.tracer[0] if event.tracer
           d.to_json + "\n"
-        rescue
+        end
+      end
+    end
+
+    class HCLogOutputter < Log4r::StderrOutputter
+      def write(data)
+        data.each do |d|
+          super(d)
         end
       end
     end