• Create a simple console program that monitors HTTP traffic on your machine
• Consume an actively-written-to w3c-formatted HTTP access log
• Every 10s, display in the console the sections of the web site with the most hits (a section is defined as being what’s before the second ‘/’ in a URL. i.e. the section for “http://my.site.com/pages/create’ is”http://my.site.com/pages“), as well as interesting summary statistics on the traffic as a whole.
• Make sure a user can keep the console app running and monitor traffic on their machine
• Whenever total traffic for the past 2 minutes exceeds a certain number on average, add a message saying that “High traffic generated an alert - hits = {value}, triggered at {time}”
• Whenever the total traffic drops again below that value on average for the past 2 minutes, add another message detailing when the alert recovered
• Make sure all messages showing when alerting thresholds are crossed remain visible on the page for historical reasons.

The project is designed as follows:

• First, a ConfigLoader will create the class parameters for each thread by reading the config file
• A Reader that reads each line of the log file, parses the lines and creates a dictionary thanks to the data extracted from the line, and then puts the data in a queue shared with a Displayer in order to print the stats. The Reader also shares a queue with the AlertSystem, containing the datetime of each line of the log file
• A Displayer that displays the statistics every 10 seconds, by reading the queue shared with the reader and prints the alert raised and recovered messages by getting the informations from a dictionary shared with the AlertSystem
• An AlertSystem that checks if an alert message should be raised by getting the elements from the queue shared with the Reader, and keeping only the elements that are at most 2 mins old
• An optional LogSimulator, that writes W3C-formatted lines to a log file

Each process is running in a different thread to enable reading the same log file, displaying the stats and the alert messages, and checking if an alert message should be raised. So the program is composed of three threads: the reader, the displayer and the alert system, and a extra optional thread with the log simulator. The advantage of this structure is that each element is independent from the others. If we want to change our reader, it will be easy. Moreover, we can add many readers to put the lines in the same queue. We can apply the same logic to the displayer and the alert system.

This program is using Python 3.5. First, you will need to install the required packages, by running the Makefile.

In order to see the algorithm works, you just need to go in the project folder, and launch the short_simulation file. This sample is running during 3 minutes with a Reader, a Displayer, an AlertSystem and a LogSimulator. During two minutes, the LogSimulator is running to enable the raising of an alert by putting a lower threshold than the real number of requests per second. Then, for the last minute, we just stop the LogSimulator to enable the number of requests per second to drop below the threshold and to display an alert recovery message.

To perform the monitoring of your own system, you will have to use the main file. But you can customize the system with the config.ini file. You can change

• Simulator: the file in which you want to write the log lines, the hostname, the number of sections on your website and if the Simulator has to be used or not
• Displayer: you can change the display interval (in the subject, it was 10 seconds)
• Reader: the path to access the log file
• AlertSystem: the threshold (maximum number of requests per second), the alert interval (in the subject, it was 2 minutes)

And then, after choosing your own parameters, you just need to launch the main file. The main file will start the thread.

I think the system can be improved with several things I didn't have time to make

• For now, the output is being printed to stdout, but we could add an option to write it to some log file instead (or any other output: emails for alerts, for instance)
• We can add a database, to handle more easily the calculation of the total traffic in the last 2 minutes, and also add other relevant statistics about the website
• We could package the script and make it executable by itself (thus removing the need to install python and dependencies)