Use fluentd infrastructure for tracing

Previously WendelinClient's tracing was controlled by global $trace
variable and was not correlated to current Fluentd log level, or current
plugin log level and thus it was harder for users to use.

Improve it and rework the tracing to use fluentd logging infrastructure.

This way tracing is disabled by default, but can be either globally
enabled with

    fluentd -v -v

or only for wendelin_out plugin via adding

    log_level   trace

to <match ...> section which routes messages to wendelin_out.

/cc @klaus

lib/fluent/plugin/out_wendelin.rb

@@ -47,7 +47,7 @@ module Fluent
             credentials['user']     = @user
             credentials['password'] = @password
         end
-        @wendelin = WendelinClient.new(@streamtool_uri, credentials)
+        @wendelin = WendelinClient.new(@streamtool_uri, credentials, @log)
     end
 
     def start

lib/fluent/plugin/wendelin_client.rb

@@ -19,18 +19,17 @@
 require 'net/http'
 require 'openssl'
 
-# show request/response traces or not
-$trace    = false
-
 
 # class representing a Wendelin client
 class WendelinClient
 
   # `streamtool_uri` - URI pointing to portal_input_data_stream "mountpoint"
   # `credentials`    # {'user' => _, 'password' => _}     TODO change to certificate
-  def initialize(streamtool_uri, credentials)
+  # `log` - logger to use
+  def initialize(streamtool_uri, credentials, log)
     @streamtool_uri = streamtool_uri
     @credentials    = credentials
+    @log            = log
   end
 
 
@@ -48,15 +47,15 @@ class WendelinClient
       # req.content_type = 'application/octet-stream'
       req.set_form_data('data_chunk' => data_chunk)
 
-      if $trace
-          puts '>>> REQUEST'
-          puts "method\t=> #{req.method}"
-          puts "path\t=> #{req.path}"
-          puts "uri\t=> #{req.uri}"
-          puts "body\t=> #{req.body}"
-          puts "body_stream\t=> #{req.body_stream}"
-          req.each {|h| puts "#{h}:\t#{req[h]}"}
-          puts
+      @log.on_trace do
+          @log.trace '>>> REQUEST'
+          @log.trace "method\t=> #{req.method}"
+          @log.trace "path\t=> #{req.path}"
+          @log.trace "uri\t=> #{req.uri}"
+          @log.trace "body\t=> #{req.body}"
+          @log.trace "body_stream\t=> #{req.body_stream}"
+          req.each {|h| @log.trace "#{h}:\t#{req[h]}"}
+          @log.trace
       end
 
       begin
@@ -73,23 +72,23 @@ class WendelinClient
 
       rescue
           # some http/ssl/other connection error
-          puts "HTTP ERROR:"
+          @log.warn "HTTP ERROR:"
           raise
 
       else
-          if $trace
-              puts '>>> RESPONSE'
-              res.each {|h| puts "#{h}:\t#{res[h]}"}
-              puts "code\t=> #{res.code}"
-              puts "msg\t=> #{res.message}"
-              puts "class\t=> #{res.class}"
-              puts "body:", res.body
+          @log.on_trace do
+              @log.trace '>>> RESPONSE'
+              res.each {|h| @log.trace "#{h}:\t#{res[h]}"}
+              @log.trace "code\t=> #{res.code}"
+              @log.trace "msg\t=> #{res.message}"
+              @log.trace "class\t=> #{res.class}"
+              @log.trace "body:", res.body
           end
 
           if res.kind_of?(Net::HTTPSuccess)       # res.code is 2XX
-              #puts "ingested ok"
+              #@log.info "ingested ok"
           else
-              puts "FAIL:"
+              @log.warn "FAIL:"
               res.value
           end
       end

test/wendelin_test.rb

@@ -5,6 +5,10 @@
 here = File.dirname(__FILE__)
 $LOAD_PATH << File.expand_path(File.join(here, '../lib'))
 require 'fluent/plugin/wendelin_client'
+require 'fluent/log'
+require 'fluent/engine' # for log
+
+log       = Fluent::Log.new(out=STDERR, level=Fluent::Log::LEVEL_TRACE)
 
 # FIXME hardcoded
 $user     = 'user'
@@ -14,7 +18,7 @@ $password = 'password'
 $erp5       = "https://example.com/erp5"                # erp5 root
 $streamtool = "#{$erp5}/portal_input_data_streams"      # where Input Stream Tool is mounted
 
-$wendelin   = WendelinClient.new($streamtool, {'user' => $user, 'password' => $password})
+$wendelin   = WendelinClient.new($streamtool, {'user' => $user, 'password' => $password}, log)
 
 
 def ingest(input_stream_ref, data_chunk)