Flask App: Display iPerf3 Logs in Real-Time

This Flask application demonstrates how to display iPerf3 logs in real-time on a webpage. It utilizes server-sent events (SSE) to stream the output of the iPerf3 command to the client.

To achieve this, we modify the start and stream routes in the Flask application:

1. start Route:

   In the start route, we append each output line from the iPerf3 command to both the stream_list and a new list called output_list. The stream_list is used for streaming the output to the client, while output_list will be used to store and display the logs on the page.

   @app.route('/start', methods=['POST'])
   def start():
       global process, output_list, stream_list
       if process:
           return jsonify({'message': 'Command already running.'})
   
       process = subprocess.Popen(['iperf3', '-s', '-p', '1111'], stdout=subprocess.PIPE, universal_newlines=True)
   
       def stream():
           while process and process.poll() is None:
               output = process.stdout.readline().strip()
               output_list.append(output)  # Add output to output_list
               stream_list.append(output)
               yield output + '\n'
   
       return Response(stream_with_context(stream()), mimetype='text/plain')
   

2. stream Route:

   In the stream route, we return the contents of the output_list as an event stream. We then clear the output_list to prevent duplicate log entries.

   @app.route('/stream')
   def stream():
       global output_list
       if output_list:
           def generate():
               while output_list:
                   output = output_list.pop(0)
                   yield output + '\n'
           return Response(generate(), mimetype='text/event-stream')
       else:
           def empty_stream():
               yield 'data: \n\n'
           return Response(empty_stream(), mimetype='text/event-stream')
   

3. Frontend JavaScript:

   In the frontend page, we use JavaScript to listen for messages from the /stream route. When a message is received, we display it on the page. Here's an example:

   var eventSource = new EventSource('/stream');
   eventSource.onmessage = function(event) {
       var log = event.data;
       // Display log on the page
   };
   

By implementing these changes, the Flask application will now stream the output of the iPerf3 command in real-time and display it on the webpage.