Develop in Python Using VS Code and WSL

PS > wsl --install

PS > wsl --list --online

PS > wsl --install -d Ubuntu-22.04

PS > wsl --list --verbose

PS > wsl --setdefault Ubuntu-22.04

PS > wsl

# code .

Windows PowerShell, Get Oriented

• The prompt is PS C:\current\path>
• %VARIABLE_NAME% is a variable

Get the latest version of PowerShell

PS > winget search Microsoft.PowerShell

PS > winget install --id Microsoft.PowerShell --source winget

Scripting with PowerShell ISE

PS > Get-ExecutionPolicy -List

PS > Set-ExecutionPolicy -Scope Process RemoteSigned

Set Up Python from Scratch on Windows

Python is not natively-installed on Windows, unlike on Linux machines. This pretty much covers it: https://learn.microsoft.com/en-us/windows/python/web-frameworks

On a fresh Debian VPN. Per WordPress.org’s own list:

sudo apt install apache2

sudo apt install php

sudo apt install php-curl

sudo apt install php-[the rest of the recommended extensions]

php -m to see a list of the php extensions installed.

sudo apt install mariadb-server

sudo systemctl start apache2

sudo systemctl start mariadb

sudo mysql_secure_installation

mysql -u root -p

sudo apt install httpd mariadb mariadb-server php php-common php-mysql php-gd php-xml php-mbstring php-mcrypt php-xmlrpc unzip wget -y

Backup the Server

To make a backup file, sudo su root then navigate to root directory, and:

tar cvpzf backup.tgz --exclude=/proc --exclude=/lost+found --exclude=/backup.tgz --exclude=/mnt --exclude=/sys /

Download the resulting file.

To restore:

tar -xvpfz backup.tgz -C /

then, mkdir /proc, mkdir /lost+found, mkdir /mnt, mkdir /sys

reboot

A Server is a Physical Computer

There are various types of servers, but they all consist of a physical computer somewhere. This tutorial shows how to set up a server first with the simplest of physical devices you can have in your home for less than $20 and side-by-side with how to do it in its more abstract – and more common – form, a VPS (virtual private server) you can rent from a hosting service.

The two procedures are very analogous. Seeing them side-by-side helps make concrete what you are actually doing even though sometimes you can’t physically see it.

Server 1. Raspberry Pi Zero W Running Raspberry Pi OS (Debian, a flavor of Linux)

Can be purchased many places, such as Microcenter or Amazon.

Server 2. VPS (Virtual Private Server) Running Ubuntu 20.04 (a flavor of Linux)

I purchased a VPS from Hostwinds. There are various operating systems available. I used Ubuntu 20.04.

Connect to Your Server over a Network (or the Internet)

Connect Via Secure Shell (SSH)

I SSH login using the MobaXterm SSH Client. The server is usually a remote computer to which you do not have physical access, so instead of plugging in a keyboard, mouse and screen, you establish a connection that gives you access to the server’s command prompt. SSH stands for secure shell, meaning the data you transfer between your computer and the server are encrypted. SSH is enabled by default in Ubuntu, but not all Linux flavors.

Useful Linux Commands: https://vitux.com/40-most-used-ubuntu-commands/

1. Raspberry Pi Zero W

Connect the Raspberry Pi Zero to your LAN. There is a way to do this with command line but the Raspberry Pi OS connects to WiFi on the initial startup, so just do it on initialization. If you want, to view the saved password with the command line to know generally where WiFi passwords are stored, use

sudo grep psk= /etc/wpa_supplicant/*

which searches the appropriate directory for “psk=” and you see the stored WiFi keys.

Enable SSH. SSH is not enabled by default with Raspberry Pi Zero. Many tutorials tell you to add a blank file to the /boot folder called SSH (no extension at all). Use the command touch ssh, then reboot. If you do this, notice once SSH is enabled then the file gets deleted so you will not see any change other than the SSH login should work.

2. VPS

On a VPS, SSH is (should be) enabled by your host to allow the purchaser to access it. You will get a default username and password from the hosting service who established the VPS with its default settings.

In MobaXterm, “Remote host” is where you specify the IP address of your server, available in your Hostwinds account.

The username is “root”

The password is whatever you set in Hostwinds

Optional: Update Operating System

1. Raspberry Pi OS

sudo apt update is the Debian update command (Raspberry Pi OS is based on Debian).

2. VPS

Update Ubuntu (only required if there is a new version of Ubuntu).*

*First, be sure you can login as the non-root super-user before updating Ubuntu as the new install will default to not allow root login. This means if you were planning to just use the existing root user with infinite powers you are now infinitely locked out of your own VPS and have to have your host re-initialize it. Your VPS host changed this setting when it set up your VPS so you can login but when you update the Ubuntu OS, the OS returns to the OS default which is to not allow SSH root login! This is a GREAT example of why to do the user basics as the very first step.

sudo do-release-upgrade

Update the advanced package tool:

sudo apt-get update (without the -get is newer, so I use it)

sudo apt update

Make Website Available Outside Your LAN

1. Raspberry Pi Zero W

Once the Pi server is serving a site on its IP within the LAN, making the site available outside the LAN (on the internet) is as simple as directing site requests that arrive to your internet IP to the Pi server. Sounds complicated, but when a browser looks for a website on the internet, it looks on port 80. Most routers have an option to direct all traffic arriving on a specific port to a specific IP within the LAN. Connect to your network’s router to configure it, usually by entering its IP (often 192.168.1.1) into a browser and logging in with a password you set. You should see an option like this under the advanced settings.

To Do: Establish an SSH Connection with SSH Keys for the Non-Root User

Normally, you generate a public and private key on your local computer then copy the public key to the server along with some settings. Hostwinds has an option in server management to generate the key, download the private key, and install the public key on the server. Reboot required.

Mariadb forked from MySQL when Oracle bought MySQL, so I use MariaDB. The XAMPP controller that establishes localhost for developing uses MariaDB.

sudo apt install mariadb-server

sudo apt install libmariadb3 libmariadb-dev python3-dev

(I don’t think this was necessary) Enable mysqli in /etc/php/7.2/apache2/php.ini by removing comment ‘;’

extension=mysqli ; nate enabled this

also:

sudo phpenmod mysql

To login to MySQL from the Linux command prompt:

sudo mysql -u root or mysql -u username -p

From the MySQL command prompt, which is “MariaDB” – a version of MySQL, same thing, various self-explanatory commands:

MariaDB [(none)]> CREATE user 'new_username'@'localhost';

SELECT user, host, authentication_string FROM mysql.user;

DROP user 'new_username'@'localhost'

CREATE USER 'new_username'@'localhost' IDENTIFIED BY 'yourpassword';

or

CREATE USER 'new_username'@'%' IDENTIFIED BY 'yourpassword';

CREATE database yourdatabasename;

GRANT SELECT, INSERT, UPDATE ON yourdatabasename.* TO 'new_username'@'localhost';

or

GRANT ALL ON ...

SHOW GRANTS FOR new_username;

ALTER USER 'new_username'@'localhost' IDENTIFIED BY 'yournewpassword';

SHOW DATABASES;

USE yourdatabasename;

CREATE table

FLUSH PRIVILEGES not required if privileges were added with the GRANT command.

Connect to MariaDB Remotely

sudo nano /etc/mysql/mariadb.conf.d/50-server.cnf

and change the bind-address line to:

bind-address = 0.0.0.0

Connect to MariaDB with Python

https://mariadb.com/resources/blog/how-to-connect-python-programs-to-mariadb

https://mariadb.com/docs/server/connect/programming-languages/c/install/#Installation_via_Package_Repository_(Linux)

sudo apt install libmariadb3 libmariadb-dev

sudo apt install build-essential libssl-dev libffi-dev python3.13-dev

pip3 install mariadb

https://mariadb.com/resources/blog/how-to-connect-python-programs-to-mariadb

sudo apt install apache2 apache2-utils apache2-dev

Upload and Enable a Site

See linux commands post here.

With the commands above, you gave the non-root super-user sufficient permission to set up sites.

Upload any site directory to /var/www/html/your_site/

Go to /etc/apache2/sites-available/ and copy the default .conf file:

cp 000-default.conf your_site.conf

and modify with the following information:

ServerName your_site.com

ServerAlias www.your_site.com

ServerAdmin you@email.com

DocumentRoot /var/www/html/your_site

Use the following command to enable the site. What it actually does is copy the .conf file from /sites-available/ to /sites-enabled/:

sudo a2ensite your_site opposite is sudo a2dissite your_site

sudo systemctl reload apache2

to show some server information:

ps aux | grep apache2 | less

#q

to get out of this command.

Astropy

Installation instructions: https://docs.astropy.org/en/stable/install.html

Astropy required Python packages.

Astropy installation files archive with various ISA support. Download the appropriate wheel file, then install with the command pip3 install /home/pi/file_name.whl.

Astropy comes with the full Anaconda install. With Miniconda, the recommended way to install Astropy is using the command conda install astropy.

Astropy Version History

Astropy 0.3.0 is what Miniconda 3.5.5 installs. This is a much earlier version than I would have expected. Astropy 0.3 was released in Nov 2013.

Astropy 0.4 was released in Jul 2014. Therefore Astropy 0.3 was the latest version when Miniconda 3.5.5 was released and is probably why Miniconda 3.5.5 installs with Astropy 0.3.

Astropy v1.2 requires Python v2.7 or later and Numpy 1.7.0 or later.

Astropy v1.3: “vectors and coordinates can be reshaped like arrays.”

Astropy v2.0.0 started to implement Python 3 but specifically says does not change functionality with Python 2. However, from 2.0.0 to 2.0.18, Python 2 was gradually phased out.

Astropy v3.0 is the first version that supports only Python 3.

I think I want Astropy v1.3 – unless it won’t run for some reason. Why does Miniconda 3.5.5 install Astropy 0.3.0? Was it the current Astropy at the release time? Answer: yes, it was. Do the newer Astropy versions require newer ISA? At some point, I got a “need ARMv7” error so probably.

However, also unexpectedly, it updates Python from 2.7.7 to 2.7.8. Python 2.7.8 was released in Jul 2014.

Astroplan

A lot of this is about Astropy and Astroplan because that’s what I was doing at the time. The main issue I remember is having to install the correct Raspberry Pi build of certain programs (I don’t remember which exactly now but the information is in here somewhere if I do again).

https://www.python.org/downloads

Raspberry Pi OS and Python versions support and description here.

The command pip3 is made for Python 3, so use it, not just pip.

• Python 3.9.2 comes installed on the Raspberry Pi OS. Python 3.9.2 was released in Feb 2021.
• Miniconda 3.5.5 installs Python 2.7.7. Python 2.7.7 was released in Jun 2014 (same month as Miniconda 3.5.5)
• The Miniconda installation instructions specifically say you can leave Python installed do not remove it (see link below under Miniconda).
• Astroplan uses the Python package Numpy. Use either the Linux command pip3 list, or python -c "import numpy; print(numpy.__version__)" to find the Numpy version installed.
  • I have Numpy 1.19.5. Is that because the legacy Miniconda installed it or because of the Python 3.9.2 installed on the Raspberry Pi OS? I think it’s the Python 3.9.2 from the OS.
  • Numpy downloads for Raspberry Pi here.
  • On my first test with Astroplan (and Astropy) I had a Numpy error that sent me to this link. The correction was sudo apt-get install libatlas-base-dev. I also updated Numpy with pip3 install numpy --upgrade and it upgraded to Numpy 1.21.5

Astropy on a Raspberry Pi Zero W

This is step-by-step how to install Astropy and Astroplan on a Raspberry Pi Zero W (1st gen, not the ‘2’).

Raspberry Pi OS download here along with imager here.

sudo passwd (change from default as desired for security)

sudo raspi-config

Set up location, time zone, language, keyboard, Wi-Fi, SSH. Turn off Bluetooth? How?

python --version

>> Python 3.9.2

sudo apt install python3-pip – for the Raspberry Pi, it is better to not use pip because it installs software not compiled for the Pi (the Pi Zero ISA is ARMv6l).

sudo apt install python3-numpy

sudo apt install python3-astropy

Note! Astropy installs this one. Not the rc2 or any of the other ones.

sudo apt install python3-pyerfa (installs with Astropy – I think)

sudo apt install python3-pyyaml (installs with Astropy – I think)

sudo apt install python3-packaging (installs with Astropy – I think)

sudo apt install python3-astroplan

sudo apt install python3-pytz (installs with Astroplan)

Other Astroplan options here.

sudo apt install python3-astroquery

sudo apt install python3-scipy

sudo apt install python3-kivy

sudo apt install fim

sudo apt install kivy

sudo apt install libmtdev1

sudo apt autoremove

Hardware

The Raspberry Pi Zero W is 32-bit and uses ARMv6 instead of the newer ARMv7. The [biggest? only?] difference is in how the processor handles floating point operations.

The Raspberry Pi Zero 2 W is 64-bit.

The Raspberry Pi OS version 11 – the latest version still – is 32-bit. A 64-bit Raspberry Pi OS is in development but not available yet.

To check the version of Raspberry Pi OS installed, cat /etc/os-release.

Python

Python comes already installed with the Raspberry Pi OS. To verify, type python --version. You could install if necessary with sudo apt install python3.8x.

sudo apt update is also a good command to run.

Deploy Flask App with Apache

This required a lot of configuration to work with WSGI, but I finally made it work for the tlom project while working at Revi North and it was very stable in the end. However, Flask isn’t so great because you’re writing html with Python, then serving the html, which javascript is much better at.

sudo apt install libapache2-mod-wsgi-py3

sudo a2enmod wsgi

Disable apache2:

sudo update-rc.d apache2 disable

sudo update-rc.d apache2 enable

sudo service apache2 restart

sudo service apache2 start

sudo service apache2 stop

Serve a Flask App from Ubuntu Apache Server with WSGI

sudo apt-get install libapache2-mod-wsgi-py3

Put the files you have been using to dev in

/var/www/app_name

Install a Local Python from Source

sudo apt install -y make build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev xz-utils tk-dev

To install dependencies.

What the following does: download source code, unpack it, make directory ~/.localpython to install into, run the configuration file setting install going to install folder, compile, install compilation, create a virtualenv pointing to the install, switch to the virtualenv to use it:

mkdir ~/src

cd ~/src

$ wget http://www.python.org/ftp/python/3.11.0/Python-3.11.0.tgz

$ tar -zxvf Python-3.11.0.tgz

$ cd Python-3.11.0

$ mkdir ~/localpython3110

$ ./configure --prefix=$HOME/localpython3110 --enable-optimizations

https://realpython.com/installing-python/#how-to-build-python-from-source-code

$ make &&make altinstall

Set Up venv

$ ~/localpython3110/bin/python3.11 -m venv py3110_venv

$ source py3110_venv/bin/activate

$ sudo apt install python3-pip -y

$ pip install --upgrade pip

$ pip install tk pillow numpy astropy astroplan pandas pytz matplotlib scikit-learn

$ pip list

$ pip -V

$ which python

$ pip install --upgrade pip

$ pip freeze --local > requirements.txt

$ deactivate

$ rm -rf somename_env

$ pip install -r requirements.txt

Note the venv folder stores neither the Python installation nor your code for your project. It is only used to store version information about the Python installation used for your project.

virtualenv instead of venv

I ran into a not-so-obscure reason to use virtualenv instead of venv. If you ever want to serve a Flask app using Apache or some other production server, virtualenv creates a file called activate_this, which Apache can use to run the Flask app in the appropriate Python environment.

sudo apt install python3-pip -y

pip install virtualenv

python3 -m virtualenv py31012_virtualenv

source py31012_virtualenv/bin/activate

pip install --upgrade pip

Install Packages from Local Folder

pip download package1 package2 -d'~/src/python-packages'

pip install package1 package2 -f ~/src/python-packages --no-index

Python Path

To see the path to the current python installation:

python -c 'import os, sys; print(os.path.dirname(sys.executable))'

To see the path variable in Windows (readable format):

PS > $env:path -split ';'