Monthly Archives: February 2022

News from the Blog 2022-02-22

My Open Source projects

zpool watch

zpool watch is a small Python program for Linux workstations with graphical environment and ZFS, that checks every 30 seconds if your OpenZFS pools are Ok.

If a pool is not healthy, it displays a message in a window using tk inter.

Basically allows you to skip checking from the terminal zpool status continuously or to having to customize the ZED service to send an email and having to figure out how to it can spawn a window alert to the graphical system or what to do if the session has not been initiated.

carleslibs

Since last News from the Blog I’ve released carleslibs v.1.06, v.1.0.5 and v.1.0.4.

v.1.0.6 adds a new class OsUtils to deal with mostly-Linux Os tasks, like knowing the userid, the username, if it’s root, the distribution name and kernel version.

It also adds:

DatetimeUtils.sleep(i_seconds)

In v.1.0.5 I’ve included a new method for getting the Datetime in Unix Epoc format as Integer and increased Code Coverage to 95% for ScreenUtils class.

v. 1.0.4 contains a minor update, a method in StringUtils to escape html from a string.

It uses the library html (part of Python core) so it was small work to do for me to create this method, and the Unit Test for it, but I wanted to use carleslibs in more projects and adding it as core functionality, makes the code of these projects I’m working on, much more clear.

I’m working in the future v.1.0.7.

CTOP.py

I released the stable version 0.8.8 and tagged it.

Minor refactors and adding more Code Coverage (Unit Testing), and protection in the code for division per zero when seconds passed as int are 0. (this was not an actual error, but is worth protecting the code just in case for the future)

Working on branch 0.8.9.

Currently in Master there is a stable version of 0.8.9 mainly fixing https://gitlab.com/carles.mateo/ctop/-/issues/51 which was not detecting when CTOP was running inside a Docker Container (reporting Unable to decode DMI).

My Books

Docker Combat Guide

Added 20 new pages with some tricks, like clearing the logs (1.6GB in my workstation), using some cool tools, using bind mounts and using Docker in Windows from command line without activating Docker Desktop or WSL.

https://leanpub.com/docker-combat-guide/

BTW if you work with Windows and you cannot use Docker Desktop due to the new license, in this article I explain how to use docker stand alone in Windows, without using WSL.

ZFS on Ubuntu

One of my SATA 2TB 2.5″ 5,400 rpm drive got damaged and so was generating errors, so that was a fantastic opportunity to show how to detect and deal with the situation to replace it with a new SATA 2TB 3.5″ 7,200 rpm and fix the pool.

So I updated my ZFS on Ubuntu 20.04 LTS book.

Python 3

I’ve updated Python 3 Exercises for Beginners and added a new example of how to parse the <title> tag from an HTML page, using Beautifulsoup package, to the repository of Python 3 Combat Guide book.

A simple example to grab the title of a page using Python and beautifulsoup4

I also added three new exercises, and solved them.

My friend Michela is translating the book to Italian. Thanks! :)

If you already purchased any of my books, you can download the updates of them when I upload them to LeanPub.

Free courses

Code Challenges

One of my students sent me this platform, which is kinda hackerrank, but oriented to video games. To solve code challenges by programming video games.

He is having plenty of fun:

https://www.codingame.com/start

More Symfony, APIs

If you enjoyed the Free Videos about Symfony, there is more.

https://symfonycast.com/screencast/api-platform

It talks about a bundle for building APIs.

And this tutorial explains in detail how to work with Webpack Encore:

https://symfonycasts.com/screencast/webpack-encore

100 Days of Code: Python Bootcamp

A friend of mine, and colleague, Michela, is following this bootcamp and recommends it for people learning from ground 0.

https://udemy.com/course/100-days-of-code/

My work at Blizzard

The company sent me the Stein, which is sent to the employees that serve for two years, with a recognition and a celebration called “The Circle of Honor”.

Books purchased

I bought this book as often I discover new ways, better, to explain the things to my students.

Sometimes I buy books for beginners, as I can get explained what I want to do super fast and some times they teach nice tricks that I didn’t know. I have huge Django books, and it took a lot to finish them.

A simpler book may only talk about how to install and work with it under a platform (Windows or Mac, as instance) but it is all that I require as the command to create projects are the same cross platform.

For example, you can get to install and to create a simple project with ORM, connected to the database, very quickly.

Software

So I just discovered that Zoom has an option to draw in the shared screen, like Slack has. It is called Annotate. It is super useful for my classes. :)

Also discovered the icons in the Chat. It seems that not all the video calls accept it.

Hardware

As Working From Home I needed an scanner, I looked in Amazon and all of them were costing more than €200.

I changed my strategy and I bought a All-In-One from HP, which costed me €68.

So I’ll have a scanner and a backup printer, which always comes handy.

The nightmare started after I tried to connect it with Ubuntu.

Ubuntu was not recognizing it. Checking the manuals they force to configure the printer from an Android/iPhone app or from their web page, my understanding is for windows only. In any case I would not install the proprietary drivers in my Linux system.

Annoyed, I installed the Android application, and it was requesting to get Location permissions to configure it. No way. There was not possible to configure the printer without giving GPS/Location permissions to the app, so I cancelled the process.

I grabbed a Windows 10 laptop and plugged the All-in-one through the USB. I ran the wizard to search for Scanners and Printers and was not unable to use my scanner, only to configure as a printer, so I was forced to install HP drivers.

Irritated I did, and they were suggesting to configure the printer so I can print from Internet or from the phone. Thanks HP, you’ll be the next SolarWinds big-security-hole. I said no way, and in order to use the Wifi I have to agree to open that security door which is that the printer would be connected to Internet permanently, sending and receiving information. I said no, I’ll use only via USB.

Even selecting that, in order to scan, the Software forces me to create an account.

Disappointing. HP is doing very big stupid mistakes. They used to be a good company.

Since they stopped doing the drivers in Barcelona years ago, their Software and solutions (not the hardware) went to hell.

I checked the reviews in the App Store and so many people gave them 1 star and have problems… what a shame the way they created this solution.

Donations

I made a donation to OpenShot Video Editor.

This is a great Open Source, multi-platform editor, so I wanted to support the creator.

Security

Attacks: looking for exploits

This is just a sample of a set of attacks to the blog in a 3 minutes interval.

Another one this morning:

Now all are blocked in the Firewall.

This is a non stop practice from spammers and pirates that has been going on for years.

It was almost three decades ago, when I was the Linux responsible of an ISP, and I was installing a brand new Linux system connected to a service called “infovia”, at the time when Internet was used with dial-up and modems, and in the interval of time of the installation, it got hacked. I had the Ethernet connected. So then already, this was happening.

The morning I was writing this, I blocked thousands of offending Ip Addresses.

Protection solutions

I recommend you to use CloudFlare, is a CDN/Cache/Accelerator with DoS protection and even in its Free version is really useful.

Fun/Games

So I come with a game kind of Quiz that you can play with your friends, family or work colleagues working from home (WFH).

The idea is that the master shares screen and sound in Zoom, and then the rest connect to jackbox.tv and enter the code displayed on the master’s screen on their own browser, and an interactive game is started.

It is recommended that the master has two monitors so they can also play.

The games are so fun as a phrase appearing and people having to complete with a lie. If your friends vote your phrase, believing is true, you get points. If you vote the true answer, you get points too.

Very funny and recommendable.

Stuff

<humor>Skynet sent another terminator to end me, but I terminated it. Its processor lays exhibited in my home now</humor>

I bought a laminator.

It has also a ruler and a trimmer to cut the paper.

It was only €39 and I’ve to say that I’m very happy with the results.

It takes around 5 minutes to be ready, it takes to get to the hot-enough temperature, and feeds the pages slowly, around 50 secs a DIN-A4, but the results are worth the time.

I’ve protected my medical receipts and other value documents and the work was perfect. No bubbles at all. No big deal if the plastic covers are introduced not 100% straight. Even if you pass again an already plasticized document, all is good.

Fun

Databases

One of my friends sent me this image.

It is old, but still it’s fun. So it assumes the cameras of the parking or speed cameras, will OCR the plate to build a query, and that the code is not well protected. So basically is exploiting a Sql Injection.

Anybody working on the systems side, and with databases, knows how annoying are those potential situations.

Python and coding

One of my colleagues shared this :)

Using Docker in Windows 10 without Windows Desktop with Docker Engine and without WSL

I added this article to my Docker Combat Guide book.

The change of license of Docker Desktop for Windows has been a low punch, a dirty one.

Many big companies use Windows as for the laptops and workstations, we like it or not.

You can setup a Linux development computer or Virtual Machine, you may argue, but things are not as easier.

Big companies have Software licenses assigned to corporation machines, so you may not use your Pycharm license in a Linux VM.

You may no use Docker Desktop either, if your company did not license it.

And finally you may need to have access to internal resources, like Artifactory, or Servers where access is granted via ACL, so only you, from your Development machine can access it. So you have to be able to run Docker locally.

After Docker introduced this changed of license I was using VirtualBox with NAT attached to the VPN Virtual Ethernet, and I port forwarded to be able to SSH, deploy, test, etc… from outside to my Linux VM, and it was working for a while, until with the last VirtualBox update and some Windows updates where pushed to my Windows box and my VirtualBox VMs stopped booting most of the times and having random problems.

I configured a new Linux VM in a Development Server, and I opened Docker API so my Pycharm’s workstation was able to deploy there and I was able to test. But the Dev Ip’s do not have access to the same Test Servers I need my Python Automation projects to reach (and quickly I used 50 GB of space), so I tried WSL. I like Pycharm I didn’t want to switch to VStudio Code because of their good Docker extensions, in any case I could not run my code locally with venv cause some of the packages where not available for Windows, so I needed Linux to run the Unit Testing and see the Code Coverage, run the code, etc…

I tried Hyper-V, tried with NAT External, but it was incompatible with my VPN.

Note: WSL can be used, but I wanted to use Docker Engine, not docker in WSL.

Installing Docker Command line binaries

The first thing I checked was the Docker downloads page.

I found the stand alone binary.

https://docs.docker.com/engine/install/binaries/#install-server-and-client-binaries-on-windows

In order to install it:

  1. Download the zip file from the page, in my case docker-20.10.12.zip
  2. Open PowerShell as Administrator
  3. Run: Expand-Archive C:\Users\carlesmateo\Downloads\docker-20.10.12.zip  -DestinationPath $Env:ProgramFiles\DockerCLI
  4. Run: cd $Env:ProgramFiles\DockerCLI\docker
  5. Run: .\dockerd.exe –register-service
  6. Run: Start-Service docker
  7. Check that Docker lists the running Containers (no errors) with: docker ps
  8. Check that the Service is running with: Get-Service docker
    You should expect something like:
Status Name DisplayName
------ ---- -----------
Running docker Docker Engine

Attempt to pull an Image with: docker pull ubuntu or docker pull php

If it works, you’re done, but most probably you will get it starting and get this error:

Error response from daemon: unsupported os linux

or this other error:

no matching manifest for windows/amd64 10.0.19042 in the manifest list entries

Depending on your system you may need to do certain things:

Turn Windows features on or off

I would make sure that are enabled:

  • Containers
  • Hyper-V
  • Virtual Machine Platform
  • Windows Hypervisor Platform
As you see WSL is not enabled

Press OK, and restart your computer.

Try Again to docker pull ubuntu

Enable Experimental Mode

Edit this file to enable experimental, you can run from the PowerShell:

notepad C:\ProgramData\Docker\config\daemon.json
Change experimental from false to: true

Save the file and restart the Service:

Restart-Service docker

Check if it works

Get-Service docker
Status   Name               DisplayName
------   ----               -----------
Running  docker             Docker Engine

Try if now it works.

Switch Daemon

If it is not working, try running:

cd "C:\Program Files\Docker\Docker\"
.\DockerCli.exe -SwitchDaemon

Give it two minutes and try to pull an image.

If it is still not working reboot, and try again:

cd "C:\Program Files\Docker\Docker\"
.\DockerCli.exe -SwitchDaemon

After it is working

I recommend you to add the new stand alone docker to the path, so you can call it from the terminal at any moment.

Edit the variable PATH of your user profile (not System wide)

I recommend you to have it on top after Python.

A simple example to grab the title of a page using Python and beautifulsoup4

A really simple code I added to my Python 3 Exercises for Beginners book, to grab the title of a Web page.

from urllib import request
from bs4 import BeautifulSoup

s_url = "https://blog.carlesmateo.com/movies-i-saw/"
s_html = request.urlopen(s_url).read().decode('utf8')

o_soup = BeautifulSoup(s_html, 'html.parser')
o_title = o_soup.find('title')

print(o_title.string) # Prints the tag string content

# Another possible way
if o_soup.title is not None:
    s_title = o_soup.title.string
else:
    s_title = o_title.title
print(s_title)

I also included this code in the code repository for Python 3 Combat Guide book.

https://gitlab.com/carles.mateo/python_combat_guide/-/blob/master/src/html_parse_beautifulsoup4.py