Kartones Blog

Be the change you wanna see in this world

Recommended Articles - 2017/01/08

  • Raspberry Pi’s PIXEL Linux desktop now available for x86 PCs: Linux is fast, but working with such a limited hardware by default means this desktop is probably even faster and smaller, perfect for old PCs and laptops.

  • Speed of development always wins. Performance problems will (eventually) get engineered away. This is nearly always how technology changes -@seldo

  • Stack on a budget: List of services with free tiers of interest to developers.

  • The Power of Less Code: Nice read. Highlights:

    • Try hard to get rid of anything that isn’t needed
    • Code is a liability. You and your teammates are responsible for each and every line of code you produce
    • Less code means less complexity, which means less bugs, which means less unexpected outcomes in production
    • Simplicity is a prerequisite for reliability. The more complex a system, the more difficult it is to build a mental model, and the harder it becomes to operate and debug it
    • [Regarding code] complete it or delete it
    • The best code is no code at all
  • Why Percentiles Don’t Work the Way you Think: One of those must reads to avoid common misconceptions, very revealing. Some highlights I wanted to keep for the future:

    • Looking at your average response time is like measuring the average temperature of a hospital. What you really care about is a patient’s temperature, and in particular, the patients who need the most help
    • Percentiles are computed from a population of data, and have to be recalculated every time the population changes. Time series databases average over varying amounts of time, and don’t have the original population.
    • Think of percentiles as wave marks on a beach
    • A distribution shows the shape of the entire population
    • Heatmaps: essentially 3d charts where histograms are turned sideways and stacked together, collected over time, and visualized with the darkness of a color
  • Everything You Know About Latency Is Wrong: Related with previous point but regarding latencies, also some fallacies and mistakes commonly made.

  • If Your Boss Could Do Your Job, You’re More Likely to Be Happy at Work

    • People don’t quit bad jobs, they quit bad bosses
    • Employees are far happier when they are led by people with deep expertise in the core activity of the business
    • Bottom line: Employees are happiest when the boss knows what she or he is talking about, and that drives performance
  • Chabuduo! Close enough...: Chabuduo means leaving things unfinished, the opposite of craftmanship. It is a sad but interesting reading, because China might be "the land of the cut corner" but this slowly is happening elsewhere.

    • "The quota, set for everything from wordcounts for journalists to arrests for policemen, is a powerful spur to value nothing about the product except the speed of its production" Doesn't it sound like KPIs?
  • The empty brain: Your brain does not process information and is not a computer: Really interesting read as it is true I often hear that we're "just very complex computers", and readings like this opens your eyes to radically different points of views (and very well argumented).

  • Take It to the Limit: Considerations for Building Reliable Systems: interesting introduction to platform limits and backpressure.

  • If you can't trust your employees to work flexibly, why hire them in the first place?: Self-explanatory title.

  • Free Design books from O'Reilly: The trick is that some are more "reports" than real books, and a few have names that sound like buzzwords, but probably there's also relevant information.

  • Don't Get Trampled: The Puzzle For "Unicorn" Employees: Good advices for equity/stock options grants to employees.

Basic Nginx snippets

I've recently migrated my hosting, finally severing all remaining ties with .NET after rewriting some remaining small experients and projects with Python. As I now have a full Linux instance to manage (at Amazon Lightsail, wanted to try it and looks I'm sticking with it), I've had to improve my Nginx skills from "barely make a site run under a Docker container" to "configure multiple static and dynamic sites running on different subdomains on the same machine". This post is a small recollection of things I needed to accomplish.

Error log default location:


Subsites inside the same root server block (note that alias paths end with / while a server root path do not):

location /mysubpath/ {
        alias /my/path/to/mysubpath/;
        try_files $uri $uri/index.html =404;

Note: It is easier to follow the recommended rule of one /etc/nginx/sites-available/<name> entry per site or subsite instead of having a root path + location and then children location with different subpaths (using alias). I made it work even combining uWSGI and static sites but the config files were more complex, so I reverted to everything in its single file with a single server block.

Proxy uWSGI Python apps through Nginx using system sockets (and as a bonus, disabling default Nginx index file matching):

index wontmatch;

location / {
        include uwsgi_params;
        uwsgi_pass unix:/tmp/mysocketname.sock;

Protect password and similar sensible files from being served:

location ~ /\. { deny  all; }

Making all path files have a default MIME type (CSV in the example):

location /mycsvs/ {
    types    { }
    default_type text/comma-separated-values;

Protecting with basic authentication (sample tutorial):

auth_basic "Password required";
auth_basic_user_file /mypathtopasswordfile/.htpasswd;

Subdomain aliases:

server_name myalias1.name.com myalias2.name.com name.com;

Custom headers:

# only for success http responses
add_header X-Custom-Header a_value;

# all http responses
add_header X-Custom-Header a_value always;


location /cv {
    return 302 $scheme://portfolio.kartones.net/curriculumvitae/;


Fully removing Server header (not only Nginx version):

sudo apt-get update
sudo apt-get install nginx-extras

sudo vim /etc/nginx/nginx.conf

# inside `http {}` section add:
server_tokens off;
more_set_headers 'Server: ';

# Save, exit and:
sudo service nginx restart

GZip all statics (Javascript, CSS, etcetera), as by default only HTML and a few others get compressed:

sudo vim /etc/nginx/ngnix.conf

# Search for `gzip_types` and replace it by:
gzip_types text/plain text/css text/js text/xml text/javascript application/javascript application/x-javascript application/json application/xml application/rss+xml image/svg+xml;

Cache expiration rules for static content: Include or adapt expires.conf inside http, server or location config blocks:

location ~* \.(?:rss|atom)$ {
        expires 1h;
location ~* \.(?:jpg|jpeg|gif|png|ico|cur|gz|zip|svg|webm|htc)$ {
        expires 1M;
        access_log off;
        add_header Cache-Control "public";
location ~* \.(?:css|js)$ {
        expires 1M;
        access_log off;

Serving Static Content: Official article, has interesting parameters if you serve big static content files (pdfs, zips and the like).

Book Review: Can holding a fart kill you?

Different book today, read recently this christmas.


Can holding a fart kill you?

Title: Can holding a fart kill you?

Author: Andrew Thompson

I've always loved science and learning where do things come from, how the work, etcetera. So I wanted to see if a "facts book" is interesting enough or not. The answer is that, while a quick read (few hours at most), it contains actually interesting questions (and answers) and not everything is as dull as the title suggests.

Some of the questions are myths, others mere history (of sentences, of events like Halloween...), other science or medicine. You can probably live without knowing them, but it wakes up your curiosity to learn more in general about life. Careful as not all the facts are for children, there are questions about drugs, guns and other violent topics.

Most descriptions are 3 small paragraphs long, and being varied topics you will surely skip some questions. I'd also would have prefered all more positive topics instead of the violence-related ones but... even so I think it adds value to general knowledge.

Recommended Articles - 2016/12/21

  • Tesla Self-Driving Demonstration: Despite the funny music, this video exemplifies why I'm happy to live in this era: Self-driving cars and how they "see" the world. Even if still has to improve, I'm amazed technology is at this stage.

  • Microsoft reboots war on sleep: Another misfortuned Microsoft campaign about Office 365, in which promotes working always, anywhere, even if they don't sleep. They should change that "creative" marketing department because it is getting quite some bad feedback...

  • Building and Motivating Engineering Teams: Based on three fundamental aspects:

    • Money
    • Purpose
    • Respect
  • Matrix Multiplication: Great website to learn or refresh matrix multiplications

  • Bruce Schneier: 'The internet era of fun and games is over': And sadly, is at least partially true, considering how inmature products that have software get to the market in general, I love technology but I'm quite reluctant to have any IoT device at home...

  • Neutralizing Intel’s Management Engine: One of those scary reads that make you not trust your computer... Didn't knew this event existed!

  • FunctionLength: Interesting opinion from the guru Fowler about writing short functions to increase legibility. Lately I'm adopting also this approach when I see either long or not easy to comprehend methods.

  • No, I have no side code projects to show you: Pretty similar to what happens to me, that my side-projects are quite small or dumb or useless, because I "work hard and go home" and when at home, not everything is coding. And it is good for mental health, I don't burnout, I do more tiny pet projects and experiments, I read more... So better focus on doing a good job and then do side-projects only if you really want to, not forcibly.

  • 'Clean your desk': My Amazon interview experience: Frightening interview story, which goes way beyond reasonable privacy limits (and anti-cheating measures). I wouldn't think a remote interview could go so bad, but on the other side, it is the clearest and quickest sign that you don't fit on that process.

  • What Makes A Senior Software Developer?: I fully agree with it, mostly because I've been on both sides of the scale (gut feeling and checklist based promotions) and both have those flaws and biasings. I won't spoil the advice of how to notice if somebody is senior to encourage reading the article, but I think it is a very good "metric".

  • On Being A Senior Engineer: Closely related with previous link, similar approach, easily summarized as "expect a “senior” engineer to be a mature engineer". But good insights and things to look at in the article, like "The Ten Commandments of Egoless Programming".

  • Geektyper: Funny but elaborated fake operating system UIs, like movie ones. You can type or open "apps" that do things on their own.

  • Work ethic has a lot more to do with showing up on time and being reliable than it does working 80 hours - @jasonfried

Pet project: Shopping Lists published

As I'm moving towards fully removing all .NET projects I had, I've spend some time migrating some C#/ASP.NET code over to Python + Flask. One of the projects that could be of some interest, if only as a sample of a simple Flask app and Python file I/O, is my Shopping Lists pet project.

It's a quick & dirty web solution but we use it at home almost daily so it serves its purpose. As at least my colleage @Saski asked me if I was going to publish the source code, now that it's migrated to Python, you can find it at my Github, alongside some simple instructions of how to setup and use it.


It was one of my new approaches to development, keeping things minimalistic and simple: the "database" are plain text files, it has minimal functionality but it works in mobile (as will be where it will be used most frequently), and while is not a code I would showcase, publishing it can help me in the future to remember some basic Flask routing and redirects syntax, reading and writing files, etcetera.

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