NanoDano's blog

Recently I took a nice long 12-hour flight with United Airlines from the US to Tel Aviv, Israel. I was excited when I learned I could purchase wi-fi during the long flight. What would I do to kill the time? Probably the same things I normally waste my time on like browsing Reddit and chatting on Discord.

Well, too bad you can't do either of those because they are blocked. I thought maybe I could get around it by installing OpenVPN from the Google Play Store and connecting to one of my remote servers. Nope, you can't access the Google Play Store either. So I can't install any games or other apps, can't chat, and can't browse Reddit.

I paid almost $30 for wi-fi access and I can't access any of the primary things that I wanted to access on my Android tablet:

• Reddit
• Discord
• Google Play Store

Building Android apps can be really easy to get started with. There is a bit of a hurdle when it comes to jumping from the debug build to a release build because it requires keystores and private keys and app signing. It can be confusing. This guide will walk through all the steps needed to build a release APK that is fit for distribution and can be uploaded to the Google Play Store.

With the knowledge in this guide, you will be able to build signed release APKs that can be distributed and uploaded to the Google Play Store.

This guide assumes you already have an Android app or know how to create one, but only using debug builds. This guide will walk through the process of creating the keystore and signing APKs with self-signed certificates for distribution on the Google Play Store.

If you don't know hot to build Android apps, check out my Android related tutorials and streams:

• NativeScript Tutorial
• Python Kivy Tutorial
• Live Coding: Android Bitcoin Price Checker (Java, Kotlin, and Python)
• Live Coding: Android Port Scanner
• Live Coding: Mobile App with Flutter
• Live Coding: Mobile App with Cordova (GPS Tool)
• Live Coding: React Native GPS Bookmarker
• Live Coding: React Native with Django REST Framework (GPS Bookmarker)

You can also read up on the official Android Developer Documentation and Android Distribution Guide.

Java has a tool named keytool that lets you do common tasks like

• Generate RSA keys and self-signed SSL certificates
• Import and export certificates
• Print certificate information
• Generate and sign certificate signing requests

It also stores everything in a secure file that has a master password in addition to specific passwords for each key it stores. You can think of it kind of like a little password protected SQLite database with your keys and certs (though there is no SQL involved).

If you have ever written an Arduino sketch or function that you want to re-use or share, creating a library for it is a great idea. In this guide, we will look at creating, importing, and using libraries. We will also look at creating and using examples that come with a library. You wil learn all the basics about managing libraries and even create your own custom library.

This guide will help you understand how to:

• Create and distribute a Arduino library ZIP
  • With examples that can be opened via File -> Examples menu
  • That can be imported via the Sketch -> Include Library -> Add ZIP Library
• Create and open sketches that are found with the File -> Sketchbook menu
• Include libraries in to your sketches

Seeed Studio offers an Arduino-compatible Nano board, Seeeduino Nano. It is like an Arduino Nano, but with some noticeable differences:

• Seeeduino Nano currently costs $6.90 and the Arduino Nano $22.00
• Seeeduino Nano has a USB-C connector instead of Mini-USB
• Seeeduino Nano comes with a Grove connector

Otherwise, it has the same Atmega328P procesor, size, and pins. You can use Nano breakout boards like the Grove Shield for Arduino Nano.

This guide will look at the board features, how to compile and upload sketches using the Arduino CLI, and how to use the Grove system modules.

Kivy can build applications for desktop and mobile including Android and iOS. The same code base can be used for both desktop and mobile, depending on what hardware devices you are trying to access.

This guide will walk through the basics of installing Kivy, building simple applications, building and packaging them for desktop and Android.

For an example of a complete project, check out my Bitcoin Price Checker example with the Live Stream on YouTube.

Alternatives for desktop application programming with Python are PyQt5, Tkinter, and wxPython. Those packages have a more traditional desktop UI but lack the Android and iOS build capabilities the same way Kivy has. Qt technically supports Android but it is not easy to build with PyQt5.

There are occassions when you want to expose a local port to the world so it can be accessed publicly on the internet.

For example, if you want to:

• Share you local development environment publicly
• Be able to receive webhooks from external services for your local development environment like Stripe webhooks
• Expose a local database to the internet via a remote server

One option is to log in to your router, typically https://192.169.1.254/ or something similar, and configure port forwarding. That will let you tell the router to take incoming traffic for a specific port and send it your local computer. This can be annoying because you have to undo the change when you are done, which is easy to forget about, and you may not have access to your router with admin privileges at all. You can also run in to port conflicts.

Another option is to use a remote host, like a VPS rented from a service like Digital Ocean to expose your port to the internet. You can do this by using SSH port forwarding (tunneling) to securely forward a port from your local computer to a port on the Digital Ocean VPS. In turn, you can expose that port on the VPS to the internet.

This example is like an exercise in setting up your own ngrok service.

This is a simple guide to Python core logging package basics. The Python logging package is very powerful and widely used. For example, Django uses Python's built-in logging package.

For the most in-depth and up-to-date information, always refer to the official Python logging documentation. This guide will walk through a summary of the things I think are most important and useful in my regular work.

Operating systems recognize a couple special file descriptor IDs:

• STDIN - 0 - Input usally coming in from keyboard.
• STDOUT - 1 - Output from the application that is meant to consumed by the user, stored in a file, or piped to another application for parsing. Typically goes to terminal.
• STDERR - 2 - Used for info, debug, and error messages to the user that are not intended to specifically be part of the application output. Typically goes to terminal.

This guide will look at how you can redirect and pipe these streams for better application development and system administration.

When you use print() in python the output goes to standard output or sys.stdout. You can directly call sys.stdout.write() instead of using print(), but you can also completely replace sys.stdout with another stream. This example will show you how to use StringIO memory files to capture and view stdout.