Author Archives: Chris Kottmyer

Monitor: Graphite, Collectd, Statsd and Graphana

Dear Reader,

Need to monitor many computers at the same time? Are you worried about a pegged CPU, memory paging, lots of swap space activity or low disk space? What about high network traffic? These things are readily available on Amazon through AWS CloudWatch.

I decided to implement 1 of 2 major monitoring stacks. The first stack is: Logstash, Elasticsearch and Kibana (ELK stack). The second group of technologies is: Collectd/Statsd, Carbon/Whisper and Graphite/Graphana.  I implemented the later.

My pre-mature conclusion is:

  1. ELK stack: Is great for text heavy documents.  Elastic Search is based on Lucene, a popular open-source search engine.
  2. Graphana/Carbon: is great for time series analysis with an emphasis on near realtime data feeds.  Collectd provides a convenient plugin/interface to operating system statistics.

Below is the Front-end component monitoring the monitoring computer (not WordPress):

Graphana Server

Graphana Server


The components of the system are:

  1. Collectd – data collection software with a plugin architecture.  Common plugins seen above include: CPU, Memory, Disk Usage, Processes, Network Traffic, Apache metrics and much more.
  2. Statsd – Used more for application monitoring.  You can send custom metrics based on set intervals.  The common 4 metrics I saw: gauges, counts, sets and intervals.  The first one takes the last of measurement within an interval and reports it.  Counts aggregate data over 10 seconds.  Sets return a unique count of values encountered (via UDP).  Intervals are time-based calculations (like rates).
  3. Carbon/Whisper – A data store focused on time series aggregation.  Data is aggregated based on two configuration files.  The first sets up regex matches (used to categorize TCP traffic) followed by a data retention policies as well as specifying polling time-frames (typically in seconds or minutes).  The second file specifies the type of aggregations available: sum, min, and max.
  4. Graphite/Graphana – Graphite is a front-end dashboard tool for carbon.   Graphana serves a similar role, but with a sleek black UI (featured above).  Both are similar to Kibana.  They both provided dashboard and graphing utilities to their respective data stores.  With Graphana being able to access other sources (like ElasticSearch).

For my Graphana localhost dashboard, I used CPU, Memory, DF and Processes modules from Collectd.

If interested in trying out the service, I can recommend the following 4 articles (Ubuntu):

digital ocean: metric tracking tutorial

For Graphana, you have to follow these instructions:

Graphana Install




Interactive Programming Diagrams

Python Tutors


Philip J. Guo is a professor of Cognitive Science at UC San Diego, who focuses on teaching programming at interactively online.  He has produced great products for both programming beginners and those interested in Python internals (10-hour lecture).

He impressed me with Python Tutors website: python tutors. Python Tutors is: Python, Java, JavaScript, TypeScript, Ruby, C and C++.  Python tutors converts Python written on the left into data structures on the right.  This provides a deeper view of what Python is actually doing.  The diagrams are step-based, which means you can see the execution of each line of code and what happens beneath the covers.  Red and Green arrows show you the line to be executed and the line being executed.  An example below.

Example (click image to go to interactive page):

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Happy Holidays,


Statistics and Machine Learning Visualizations

Visually Explained

At work, a software engineer provided a link to interactive data visualizations.  The visualization shows a statistical model and their fit with data.  The data points can be moved/modified instantly influencing the model.  It’s a fun way of seeing how a model works.

Interactive Data Visualizations: Statistics Models

Example Interactive VisualizationExample Interactive Visualization

The models and concepts available are: PCA, OLS, Conditional probability, Markov Chains, Eigenvectors and Image Kernels.


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Machine Learning: Part 1

Introduction to Python Courses

Dear Reader,

I am providing free lectures on intro-to-python.  Salesforce supporting me through their voluntary time off program. under it’s 1-1-1 program gives each employee 7 days to work on voluntary projects.

You can find the lectures here:



Application Class

The 4th class will be held at Cambridge Innovation Center, 1 Broadway, Cambridge Ma on Saturday November 18th 2017.  They are held every 2nd Saturday afterwards.  Possible projects:

  1. A mini Q/A program.  It introduces the concept of regex using re.
  2. Opening a file in python, reading it’s lines and analyzing words.
  3. Utilizing SimpleHttp server host a basic webpage with <p>, <h1> and <div> tags.  This is a simple introduction to a one-line web server.

The curriculum is free and I encourage people to submit practice problems to the GitHub repository.

Moodle Platform

Moodle is an open-source learning platform. Often, Moodle is used in universities.  I plan on implementing a Moodle instance to host lectures online.

Spammy E-mails, Great!

Moodle implementation has stalled.  I decided to host e-mail service myself.  I did get smtp and e-mail server up.  The obstacle now is getting Google and other e-mail providers to realize my E-mail isn’t spam.

Why is it considered SPAM?

Evidently, you can send an E-mail from, but claim it originated from john  Web industry has developed two processes to prevent this: SPF and DKIM.  SPF creates a guarantee that a message from originates from  DKIM encrypts SMTP header preventing snoopers from changing that in transit.

Apache and VPL!

After resolving the spam crisis, I will have to deal with an annoying URL issue.  Moodle loves my IP address.  It loves it so much, it’s bound it to all the URLs.  I don’t like!  I’ll have to make either application-level change or re-route in Apache to resolve.

Having Moodle is great.  It doesn’t support programming assignments out of the box.  Luckily, some wonderful academics invented a plugin called the VPL.  It takes code presented to the web, submits it to a restrictive JVM-based sandbox and runs it.  It should prevent any malicious hackers from hijacking the server (crossing fingers).  It also supports automated grading of coding exercises (yay!).

Both issues aren’t blocking the lectures!  Hopefully everyone can enjoy those!




Yoast App

Yoast Application for WordPress

Yoast Application for WordPress


Yoast (website) is a group dedicated to SEO, which provides a free WordPress plugin to improve your website.  The plugin has useful features.  For example, it computes a readability score and scores your post for Google keywords:

Yoast plugin


Yoast plugin makes suggestions to improve readability of your blog posts.  On Yoasts website, you will see a summary of how to plan blog posts:

Practical tips to set up a clear text structure

Within the practical tips webpage, Yoast explains the importance of headers (<h1>,<h2>…).  Headers, larger text found above paragraphs, provide context about the paragraphs that follow.  This provides Google with benefit when matching search queries with your website.  The post discusses the use of transition words to connect and smoothen the flow of the paragraphs.  Yoast app automatically calculates this for the blog post you are typing.  It recommends that 30% of words be transition words.

Transition words are one of three main metrics I often work on to improve posts.  The other two are active vs passive voice and Flesch Reading Score.  Active voice places the emphasis of the sentence as the main object instead of the subject.  For example, “Chris plays the trumpet” is active voice vs passive “the trumpet is played by Chris.  Active voice is considered less confusing then passive voice. With passive voice, it is harder to figure out what the sentence is about.  More about passive voice below:

Passive voice

The last metric on readability is the Flesch Reading Ease test (wiki:Flesch-Kincaid readability test).  Flesch test provides a formula that is supposed to correlate with ease of use:


Flesch-Kincaid Formula


Flesch Score Results

Formula Conclusion

The major conclusion from this formula is that you want short sentences with few syllables.  This style of writing correlates with easier comprehension.  It also decreases the odds people will run away from your website.


Key Words

Another section of Yoast focuses on key words.  Key words are words in Google search queries that you would like your post to be associated with.  For example, I might want this specific blog post to show up when people type: “Improve blog post readability” or “Yoast features” into Google.  The underlined words would be my key words. The plugin provides key metrics on your chosen keyword:

Keyword Analysis

How do I look on Google?

The last cool feature worth mentioning is you can edit how you look like on Google.  Evidently, a website can provide some metadata (data about the webpage to Google), which tells Google how to present your webpage as a search result.  The below form provides SEO Title, the blue name (hyperlink) of your website.  A slug, which is the end of your url, in the below case (yoast is the slug):  As well as the description google uses for your webpage.

Google Metadata

Overall, Yoast provide a really cool tool set to improve your blog posts.  It also provides a study into what an expert thinks is great content.  Hoping this helps readers develop better content and improve their own readability!

Best luck blogging!


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