Update microservice-orchestration/Step6 for live logs. (#238)

Signed-off-by: Travis Hunt <[email protected]>

_posts/2018-09-22-microservice-orchestration.markdown

@@ -964,7 +964,6 @@ set :protection, :except=>:path_traversal
 redis = Redis.new(url: ENV["REDIS_URL"] || "redis://localhost:6379")
 
 Dir.mkdir("logs") unless Dir.exist?("logs")
-cache_log = File.new("logs/extraction.log", "a")
 
 get "/" do
   "Usage: http://<hostname>[:<prt>]/api/<url>"
@@ -980,7 +979,9 @@ get "/api/*" do
     redis.set(url, jsonlinks)
   end
 
+  cache_log = File.open("logs/extraction.log", "a")
   cache_log.puts "#{Time.now.to_i}\t#{cache_status}\t#{url}"
+  cache_log.close
 
   status 200
   headers "content-type" => "application/json"
@@ -1104,6 +1105,16 @@ Now, open the web interface by [clicking the Link Extractor](/){:data-term=".ter
 Also, try to repeat these attempts for some URLs.
 If everything is alright, the web application should behave as before without noticing any changes in the API service (which is completely replaced).
 
+We can use the `tail` command with the `-f` or `--follow` option to follow the log output live.
+
+```.term1
+tail -f logs/extraction.log
+```
+
+Try a few more URLs in the web interface. You should see the new log entries appear in the terminal.
+
+To stop following the log, press `Ctrl + C` keys while the interactive terminal is in focus.
+
 We can shut the stack down now:
 
 ```.term1