DEV: Consolidate Unicorn error backtraces when logstash is enabled.

lib/unicorn_logstash_patch.rb

@@ -0,0 +1,12 @@
+# See https://github.com/defunkt/unicorn/commit/5f478f5a9a58f72c0a844258b8ee614bf24ea9f7
+# Unicorn originally logs backtrace line by line with `exc.backtrace.each { |line| logger.error(line) }`.
+# However, that means we get a separate logstash message for each backtrace which isn't what we want. The
+# monkey patch here overrides Unicorn's logging of error so that we log the error and backtrace in a
+# single message.
+module Unicorn
+  def self.log_error(logger, prefix, exc)
+    message = exc.message
+    message = message.dump if /[[:cntrl:]]/ =~ message
+    logger.error "#{prefix}: #{message} (#{exc.class})\n#{exc.backtrace.join("\n")}"
+  end
+end