Quick References

As a constant learner, I get to touch upon many ideas in different areas. This category is for me to capture those ideas which I felt people may reference to get ahead of their tasks. Most of the time, I do come back to this section of my blog to remember what I had learnt in the past.

How to deploy Python 3 Flask application on Raspberry Pi 3 with Raspbian Stretch Lite, Nginx, Supervisor, Virtualenv and Gunicorn

Raspberry Pi 3 Model B boards make good gifts for programmers and if someone had gifted you with one, you may want to use it as a control center for interacting with various IoT sensors and devices at home.

In such a situation, you may want to build a Python 3 Flask application to present the web interface for accessing the control center.

After you had built that Python 3 Flask application, the next step will be to deploy it on your Raspberry Pi 3 for serving HTTP requests.

This post discusses how you can deploy a Python 3 Flask application on Raspberry Pi 3 with Raspbian Stretch Lite, Nginx, Virtualenv and Gunicorn.

Configuring Nginx for PHP web applications

Nginx and PHP FastCGI Process Manager (FPM) are often used side by side for PHP applications. In such a setting, Nginx will be the first point of contact for incoming HTTP requests, acting as a reverse proxy server for the PHP FastCGI Process Manager.

The PHP FastCGI Process Manager then interprets the HTTP requests that it receives from Nginx and runs the PHP scripts for generating the corresponding HTTP responses for Nginx to return back to the HTTP client.

This post discusses a set of configurations that you can use for configuring Nginx for your PHP web applications.

Configuring Nginx to serve files for a static website

In the world of HTTP, static files are content hosted on a web server that does not change. Some examples of static files include images, CSS files, JavaScript files and HTML files.

Although it is not too hard to implement a dynamic website through a content management framework like WordPress on your own server, there are cases where it makes more sense to just host a couple of static files to realise your website.

Nginx is an excellent web server for serving static websites. If you already have Nginx running on a Raspberry Pi 3 or any other kinds of server, you may want to configure it to serve files for your static website.

How to migrate your MySQL / MariaDB database with mysqldump, tar and scp

If you had been building the content for your new WordPress site on a Raspberry Pi 3, there will come a time when you need to migrate the underlying MySQL database to another machine, for eg. a DigitalOcean droplet, for production usage.

MySQL provides us with the mongodump client utility to produce a set of SQL statements that can be executed to reproduce the original database object definitions and table data.

A simple MySQL database migration can be performed with the following steps:

  1. Use mysqldump to get the set of SQL statements that can be executed to reproduce the original database object definitions and table data.
  2. If the mysqldump output is too big, use the tar command to compress it.
  3. Use the scp command to send the mysqldump output from the source server to the destination server.
  4. If you had used the tar command to compress the mysqldump output, use the tar command at the destination server to decompress it.
  5. Execute the set of SQL commands in the mysqldump output at the destination server.

This post documents how you can migrate your MySQL / MariaDB database with utilities provided by MySQL and most Linux servers.

Building a reverse proxy server with Nginx, Certbot, Raspbian Stretch Lite and Raspberry Pi 3

The Nginx reverse proxy server runs well on Raspberry Pi 3 and you can use it behind a router to route HTTP traffic to upstream web applications.

A Raspberry Pi 3 reverse proxy server is a very useful appliance to help us host multiple websites from home.

Some examples of web applications that you may want to host at home includes:

This post discusses how you can build a reverse proxy server with nginx, Certbot, Raspbian Stretch Lite and Raspberry Pi 3 to proxy HTTP traffic directed at applications on your home network.

How to migrate your MongoDB database instance with mongodump, mongorestore, tar and scp

Migration of MongoDB database is part and parcel of DevOps, especially when you are running your own projects.

MongoDB provides us with two utilities for performing database migration – mongodump and mongorestore.

A simple MongoDB database migration can be performed in 5 steps:

  1. Use the mongodump command to export the data of a MongoDB database instance as files in the source server’s filesystem.
  2. Use the tar command to compress the exported files as a single .tar.gz file in the source server’s filesystem.
  3. Use the scp command to send the .tar.gz file from the source server to the destination server.
  4. Use the tar command to decompress the .tar.gz file at the destination server.
  5. Use the mongorestore to import the extracted files into the destination MongoDB database.

This post discusses how you can perform MongoDB database migration with utilities provided by MongoDB and most Linux servers.

Understanding the difference between the root and alias directives in Nginx

Nginx is a web server that is good for serving as a reverse proxy server, load balancer or HTTP cache.

One of the most important task in configuring Nginx to proxy HTTP / HTTPS traffic is telling Nginx where to look for files that it needs for serving HTTP / HTTPS requests.

This posts discusses the root and alias directives that we can use in Nginx configuration files for mapping a url from a HTTP request to a file on the server file system.

Installing Certbot on Raspbian Stretch Lite for obtaining Let’s Encrypt’s browser-trusted certificates

By offering free browser-trusted certificates, Let’s Encrypt makes it easy for ordinary folks like you and me to deploy secure web applications that serve HTTPS traffic 24-7.

The issuance of Let’s Encrypt certificates is automated by software participating in the ACME protocol. We will need to run such a software on devices which host web servers serving HTTPS traffic.

The Raspbian Stretch Lite operating system is a way to create performant web-based appliances with Raspberry Pis. If you need to secure your web-based applications on Raspbian Stretch Lite, you may choose to install Certbot on Raspbian Stretch Lite as a first step.

This post extends Certbot’s installation instruction on Debian Stretch to provide the steps for installing Certbot on Raspbian Stretch Lite.

How to setup Raspbian Stretch Lite on Raspberry Pi 3 to run Python 3 applications

Raspbian Stretch Lite operating system is the Raspberry Pi Foundation’s official supported operating system for running headless software. It is a good operating system for different Raspberry Pi 3 use cases. Some examples include:

If you are planning to use Raspberry Pi 3 GPIO to interface with the real world, it is recommended that you setup Raspbian Stretch Lite to run Python 3 applications.

This post provides the steps to setup Raspbian Stretch Lite on Raspberry Pi 3 for running Python 3 applications.