Category Archives: Web development

A super simple HTML jQuery JavaScript to hide a text

Some of my students are working on the Front End part, so I help them with JavaScript and jQuery.

Even if I’m super strong in Back End I’m not bad at JavaScript Front End.

So this super simple code will hide the paragraphs <p> using the hide animation from jQuery.

<html>
    <head>
    	<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
    </head>
    <body>
        <p>Text to hide</p>
        <input type="button" id="button" value="Hide the text" onclick='$("p").hide(1000);'>
    </body>
</html>

I think learning should be taken by steps, and starting by the most simple.

Front End (Beginners): Check if an AJAX request is made

I created this little video to show how to use the Web Developer Tools to check if jQuery AJAX request is being made.

This is to help beginners in their journey learning to program Front End.

Please be aware that the page I used makes their own calls for marketing purposes. I cleared several times the history to show what is the real AJAX request we are doing.

Note: The recording program did not capture correctly the mouse position and this video has no sound.

The page I shown is:

https://www.w3schools.com/jquery/tryit.asp?filename=tryjquery_ajax_ajax

And some more info about jQuery .ajax method:

https://www.w3schools.com/jquery/ajax_ajax.asp

Normally you can try your HTML and JavaScript from your browser, opening the HTML file. However there are Security restrictions when it applies to AJAX requests or trying to access a local file from the browser.

You’ll need to run your JavaScript from an HTML page server from a Web Server. You can install apache if you use Linux, or WAMP if you use Windows or MAMP (Mac Apache MySQL PHP) if you use Mac or if you know how to you can create a Docker Container.

When you’re programming and your code does not trigger, pay attention to errors:

Top right, red circle, shows one error

Renewing a SSL Certificate for Apache2 in Ubuntu 20.04

First you have to generate a new csr and key files.

It is not recommended to reuse your old CSR file.

openssl req -new -newkey rsa:2048 -nodes -keyout blog_carles_mateo_com_2022.key -out blog_carlesmateo_com_2022.csr

As you can see I used the name of the domain and the year for the new files to be generated to easily distinguish them.

When you’re asked for the password, in the additional fields, keep that password safe in case you need the Cert to be reissued to you.

You’ll need to submit the CSR file to your SSL provider. They will return you the CRT and the CA-BUNDLE files.

Edit your Apache config file for the SSL site.

For example:

/etc/apache2/sites-enabled/11-https-blog-carlesmateo-com.conf

Your conf file will look similar to this:

<VirtualHost *:443>
	ServerAdmin webmaster@yourdomain.cat

	DocumentRoot /opt/sites/www/blog.carlesmateo.com
	ServerName blog.carlesmateo.com
        SSLEngine on
        SSLCertificateFile /opt/sites/certs/2022/blog_carlesmateo_com_2022.crt
        SSLCertificateKeyFile /opt/sites/certs/2022/blog_carlesmateo_com_2022.key
        SSLCertificateChainFile /opt/sites/certs/2022/blog_carlesmateo_com_2022.ca-bundle
...

Before restarting Apache2, test the configuration for syntax errors with:

apache2ctl -t

If all is good, restart your Web Server with:

service apache2 restart

With a browser, verify that the information of the domain is right. I recommend you to check in Firefox and Chrome at least.

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.

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 :)

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

News from the Blog 2021-11-11

New Articles

How to communicate with your Python program running inside a Docker Container, using Linux Signals

Hope you’ll have fun reading this article:

Communicating with Docker Containers via Linux Signals and Python

I migrated my last services from Amazon and the blog to Google Compute Engine (GCE / GCP)

I wrote a Postmortem analysis about the process of migrating my last services from my 11 year old Amazon account.

Updates

Updates to articles

I updated the article about Python weird things that you may not know adding the Ellipsis …

I’ve been working in some Cassandra examples. I may publish an article soon about using it from Python and Docker.

Updates to My Books

I updated my Python and Docker books.

I’m currently writing a book about using Amazon AWS Python SDK (boto3).

Updates to Open Source projects

I have updated ctop, fixed two bugs and increased Code Coverage.

I made a new tag and released the last Stable Version:

https://gitlab.com/carles.mateo/ctop/-/tags/0.8.7

On top of my local Unit Testing, I have Jenkins checking that I don’t commit anything that breaks the Tests.

Some time ago I wrote some articles about how you can setup jenkins in a Docker Container.

Miscellaneous

Charity

I’ve donated to Wikipedia.

Only 2% of the viewers donate, so I answered the call every time it was made.

This is my 5th donation to Wikimedia.

I consider that Freedom is very important.

I bought these new books

One of my secrets to be on top is that I’m always studying.

I study all the time, at work and in my free time.

I use Linux Academy and I buy books in paper. I don’t connect with reading in tablets. I think information is stored better when read in paper. I use also a marker and pointers to keep a direct access to the most interesting points on the books.

And I study all kind of themes. Obviously I know a lot of Web Scraping, but there is always room for learning more. And whatever new I learn helps me to be better with my students and more clear writing my books.

I’ve never been a Front End, but I’ve been able to fix bugs in the Front End engines from the companies I worked for, like Privalia. I was passed a bug that prevented the Internet Explorer users to buy just one hour before we launching a massive campaign. I debugged and I found a variable named “value” so the html looked like <input name="value" value="">. In less than 30 minutes I proved to the incredulous Head of Development and the CTO that a bug in Internet Explored was causing a conflict when fetching the value from the input named value. We deployed to Production the update and the campaign was a total success. So I consider knowing Javascript and Front also a need, even if I don’t work directly with it. I want to be able to understand all the requirements and possibilities, and weaknesses, so I can fix bugs and save the day. That allowed me to fix scalability problems in Nodejs and Phantomjs projects too. (They are Javascript Server Side, event driven, projects)

It seems that Amazon.co.uk works well again for Ireland. My two last orders arrived on time and I had no problems of border taxes apparently.

Nice Python article

I enjoyed a lot this article, cause explains part of what I did with my student and friend Albert, in a project that analyzes the access logs from Apache for patterns of attempts of exploits, then feeds a database, and then blocks those offender Ip Addresses in the Firewall.

The article only covers the part of Pandas, of reading the access.log file and working with it, but is a very well redacted article:

https://mmas.github.io/read-apache-access-log-pandas

Nice Virtual Volumes article from VMware

I prefer Open Source, but there are very good commercial products too.

I liked this article about Virtual Volumes from VMWare:

Understanding Virtual Volumes (vVols) in VMware vSphere 6.7/7.0 (2113013)

https://kb.vmware.com/s/article/2113013

Thanks Blizzard (again)

There is a very nice initiative where we can nominate 4 colleagues a year, that we think that deserve a recognition.

My colleagues voted for me, so I received a gift voucher that I can spend in Ireland stores like Ikea, Pc World, Argos, Adidas, App Store & iTunes…

So thanks a million buds. :)

Migrating my 11 years Amazon AWS account services (Postmortem Analysis)

I started to explain that I was migrating some services from Amazon and that some of my sites were under Maintenance and that I would provide more information.

Here is the complete history of why I migrated all the services from my 11 years old Amazon account to other CSP.

Some lessons can be learned from my adventure.

I migrated my last services from Amazon to GCP

Amazon sent me an email on October 6th, this year 2021, telling me that they will disable EC2-Classic by August 2022. I thought I would not be able to keep my Static Ip’s as in the past VPC Ip’s and EC2-Classic Ip’s were not transferable, so considering that I would loss my Static Ip’s anyway I started to migrate to some to other providers like Digital Ocean.

Is not cool losing Static Ip (Elastic Ip in AWS) Addresses as this is bad for SEO, so given that I though I would lose my Static Ips that have been with me for years, I started to migrate certain services to providers much more economic.

Amazon is terrible communicating, and I talked with some product managers in the past about that, when they lost one of my Volumes, and the email was so cold and terrible that actually that hurt more than Amazon losing my Data. I believed that it was a poorly made Scam and when I realized it was true I reached one of my friends, that is manager there, as I know they care for doing things right, and he organized a meeting with two PM so I can pass my feedback.

The Cloud providers are changing things very fast, and nobody is able to be up to date with the changes, unless their work position allows plenty of time to get updated. Even if pages of documentation are provided, you have to react to an event that they externally generated forcing you to action. Action to read all the documentation about EC2-Classic migrations, action to prepare to have migrated by August 2022.

So August 2022… I was counting that I had plenty of time but I’m writing a new book about using the Amazon SDK for Python, boto3, and I was doing some API calls and they started to fail in a very unusual way, Exceptions with timeout, but only for the only region where I had EC2-Classic.

urllib3.exceptions.NewConnectionError: <botocore.awsrequest.AWSHTTPSConnection object at 0x7f0347d545e0>: Failed to establish a new connection: [Errno -2] Name or service not known

My config was:

        o_config = Config(
            region_name="us-east-1a",
            signature_version="v4",
            retries={
                'max_attempts': 10,
                'mode': 'standard'
            }
        )

But if I switched to another region name, it would work:

            region_name='us-west-2',

I made a mistake in here, the region name is “us-east-1” and not “us-east-1a“. “us-east-1a” is the availability zone. So the SDK was giving a timeout because in order to connect to the endpoint it uses the region name as part of the hostname. So it doesn’t find that endpoint because it doesn’t exist.

I never understood why a company like Amazon is unable to provide the SDK with a sample project or projects 100% working, with the source code so people has a base that works to build up.

Every API that I have created, I have provided it with documentation but also with example for several languages for how to use it.

In 2013 I was CTO of an online travel agency, and we had meta-searchers consuming our API and we were having several hundreds of thousands requests per second. Everything was perfectly documented, examples were provided for several languages, the document and the SDK had version numbers…

Everybody forgets about Developers and companies throw terrible and cold products to the poor Developers, so difficult to use. How many Developers would like to say: Listen Mr. President of the big Cloud Company XXXX, I only want to spawn a VM that works, and fast, with easy wizards. I don’t want to learn 50 hours before being able to use your overpriced platform, by doing 20 things before your Ip’s are reflexes of your infrastructure and based in Microservices. Modern JavaScript frameworks can create nice gently wizards even if you have supercold APIs.

Honestly, I didn’t realize my typo in the region and I connected to the Amazon Console to investigate and I saw this.

Honestly, when I read it I understood that they were going to end my EC2 Networking the 30th of October. It was 29th. I misunderstood.

It was my fault not reading it well to the end, I got shocked by the first part telling about shutdown and I didn’t fully understood as they were going to shutdown EC2-Classic for the zones I didn’t had anything running only.

From the long errors (3 exceptions chained) I didn’t realize that the endpoint is built with the region name. (And I was passing the availability zone)

botocore.exceptions.EndpointConnectionError: Could not connect to the endpoint URL: "https://ec2.us-east-1a.amazonaws.com/"

Here is when I say that a good SDM would had thought and cared for the Developers more, and would had made the SDK to check if that region exists. How difficult is to create a SDK a bit more clever that detects a invalid region id?. It is not difficult.

It is true that it was late in the evening and I was tired of all the day, and two days of the week between work and zoom university classes I work 15 hours and 13 hours respectively, not counting the assignments, so by the end of the week I am very tired. But that’s why it is very important to follow methodology and to read well. I think Amazon has 50% of the fault by the way they do things: how the created the SDK, how they communicate, and by the errors that the console returned me when I tried to create a VPC instance of an EC2-Classic AMI (they seem related to the fact I had old VPC Network objects with shorter hash than the current they use) and the other 50% was my fault for not identifying the source of the error, and not reading the message in their website well.

But the fact that there were having those errors in the API’s and timeouts made me believe they were going to cut the EC2-Classic Networking the next day.

All the mistakes fall together in a perfect storm.

I checked for documentation and I saw it was possible to migrate my Static Ip’s to VPC Static Ip’s.

It was Friday evening, and I cancelled my plans, in order to migrate the Blog to VPC in an attempt to keep running it with Amazon.

As Cloud Architect, I like to have running instances in several CSP as it allows me to stay up to date with the changes they do.

I checked the documentation for the migration. Disassociating the Static Ip (Elastic Ip in AWS jargon) was easy. Turning into VPC as well.

As I progressed, what had to be easy turned into a nightmare, as I was getting many errors from the Amazon API, without any information, and my Instances were not created.

I figured out that their API could have problems with old VPC objects I created time ago, so I had to create new objects for several things.

I managed to spawn my instances but they were being launch and terminated instantly without information. Frustrating.

When launching a new instance from the AMI (a Snapshot of the blog), I was giving shown options to add more volumes without any sense. My Instance was using 16GB from a 20GB total Space, and I was shown different volume configs, depending on the instance, in some case an additional 20GB volume, in other small SSD, ephemeral and 10 GB for the AMI (which requires at least 16GB).

After some fight I manage to make it work after deleting the volumes that made no sense, and keeping only one of 20GB, the same size of my AMI.

But then my nightmare started to make the VPC Instance to have Internet access and to be seen from outside. I had to create a new Internet Gateway, NAT, Network, etc…

As mentioned the old objects I was trying to reusing were making the process to fail.

I was running out of time, and I thought in few time they were going to shutdown EC2-Classic network (as I did not read correctly), so I decided to download everything and to migrate to another provider. For doing that first I blocked all the traffic, except for my Ip.

I worked in parallel, creating the new config in Google Cloud, just in case I had forgot something. I had created a document for the migration and it was accurate.

I managed to do everything fast enough. The slower part was to download all the Data, as I hold entire VM’s for projects like Cassandra Universal Driver.

Then I powered off my Amazon Instance for the Blog forever.

In GCP I blocked all the traffic in the firewall, except for my Ip, so I could work calmly.

When everything was ready, I had to redirect the DNS to the new static Ip from Google.

The DNS provider I used had implemented some changes in their API so I was getting errors replacing my old entry ‘.’ (their JSON calls returned Internal Server Error). Finally I figured it out how to workaround it and I was able to confirm that the first service was up and running.

I did some tests to make sure there were not unexpected permission problems, entries in the logs, etc…

Only then I opened the Google Firewall. I have a second firewall in each instance where I block or open at Ip tables level what I want. Basically abusive bot’s IPs trying to find exploits or brute force by dictionary passwords.

I checked with my phone, without Wifi that the Firewall was all good. (It is always a good idea to use another external Ip, different from the management one, to check)

I added a post explaining that I was migrating some of my Services and were under maintenance.

I mentioned in the blog that some of my services were being migrated from Amazon to Digital Ocean.

For some reasons, in the Backup of the Database one user was lost, so I created it in the MySQL with the typical commands:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
FLUSH PRIVILEGES;
GRANT ALL PRIVILEGES ON mydatabase.* TO 'username'@'localhost';

My Sites are under Maintenance

2021-11-08 Update: There is a Postmortem analysis of what happened with Amazon here.

TLTR: I’m undergoing a Maintenance on all my sites.

The main reason was that I was getting unexpected API Exceptions on the AWS SDK for Python (boto3), so I connected to the AWS Console to get more information.

Then I saw a message indicating that they will stop EC2-Classic today 30th of October. (Please read the Update on the Postmortem analysis as I understood incorrectly that banner message)

I already started migrating my Services, some I move to other providers like Digital Ocean. Other I had plant to keep in Amazon.

EOL (End of Life) was scheduled for 2022 August, so when I saw the message from Amazon the evening of the 29th, I decided to migrate my EC2-Classic Public Ip’s and Compute to VPC. Trying to deploy from an AMI, Amazon APIs were returning many internal errors, and as I figured out where their failures would be I was able get instances being launch without being Terminated immediately without an explanation. Still I had many problems with the Internet Gateway, VPC NAT, etc… after hours fighting with their errors, and their console, that is more a bunch of pages to manage Infrastructure rather than a user/developer friendly Cloud Tool I decided that I had enough.

After 11 years using Amazon AWS, including a trip to Dublin to be hired as Manager for Cloud Watch, and giving them the idea to add AutoScaling (I was told the project was too easy for me and that I would get bored in a year or too so I was not hired), I decided to move my Services to Google Cloud and to Digital Ocean.

I’m very polite and I saw that when I told to one Manager that the User Interface was terrible he didn’t like, but I have to speak up and say that tools for developers cannot be cold as your evil girlfriend. Cannot be API alike, stand alone pages to manage infinite parts of Architecture. Web providing services for developers cannot be created like in cold SysAdmin style. If the infrastructure is hard to manage and internally you use APIs, build nice Wizards in Javascript. I was leading a Team of Developers with infinite less resources than Amazon or Google and we wrote a Multi-Cloud product, with nice, and clever, and easy to use Wizards, and they were infinitely more better that those giant CSPs. We won a prize at European level at that time. But it was 2013.

I’ve migrated everything, moved all the data, statics, VMs… but I’m completing the adjustments for certain services like Cassandra nodes, web sites, bootstrapping some of my sites based of my PHP Catalonia Framework, adding Firewall rules to GCP, doing changes for Ansible provisioning, deploying the Server scripts from IaC, Docker, etc…

I’ll be posting updates in Twitter.

Web Top – Displaying top with Python 3 Web Server and Carleslibs

So this is a super simple example on how quickly you can create nice solutions with my package carleslibs.

In this example I use Python 3 incorporated Web Server and carleslibs, to execute top and display in the browser.

Requisites:

Having Python3 and have installed carleslibs 1.0.1 or superior.

pip3 install carleslibs

Having this running in a Linux with top installed. All of them come with top, as long as I know.

This is the 84 lines code for WebTop:

from http.server import BaseHTTPRequestHandler, HTTPServer

from carleslibs.subprocessutils import SubProcessUtils
from carleslibs.datetimeutils import DateTimeUtils


class Top():

    def __init__(self, o_subprocess):
        self.o_subprocess = o_subprocess

    def get_top(self):

        a_domains_offline = []

        s_command = "/usr/bin/top -n 1 -b"
        i_code, s_stdout, s_stderr = self.o_subprocess.execute_command_for_output(s_command, b_shell=True, b_convert_to_ascii=True)

        return i_code, s_stdout, s_stderr


class WebServer(BaseHTTPRequestHandler):

    def do_GET(self):
        o_subprocess = SubProcessUtils()
        self.o_top = Top(o_subprocess)

        self.o_datetime = DateTimeUtils()

        self.i_max_domains_offline = 0

        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()

        WebTop.log(self.path)
        if self.path == "/favicon.ico":
            return

        s_html = "<html><body>"
        s_html = s_html + "<h1>Web Top</h1>"
        s_html = s_html + '<small>by Carles Mateo - <a href="https://blog.carlesmateo.com">blog.carlesmateo.com</a></small>'

        i_code, s_stdout, s_stderr = self.o_top.get_top()

        if i_code != 0:
            s_html = s_html + "Error Code: " + str(i_code) + "&lt;/br&gt;"
            s_html = s_html + "Message: " + s_stderr + "&lt;/br&gt;"
        else:
            s_html = s_html + "<pre>"
            s_html = s_html + s_stdout
            s_html = s_html + "</pre>"

        s_html = s_html + "</body>"
        s_html = s_html + "</html>"

        by_html = bytes(s_html, encoding="utf-8")

        self.wfile.write(by_html)


class WebTop():

    o_datetime = DateTimeUtils()

    @staticmethod
    def log(s_text):
        s_datetime = WebTop.o_datetime.get_datetime()
        print(s_datetime, s_text)


if __name__ == "__main__":

    o_webserver = HTTPServer(("localhost", 80), WebServer)
    WebTop.log("Server started")

    try:
        o_webserver.serve_forever()
    except KeyboardInterrupt:
        pass

    o_webserver.server_close()
    WebTop.log("Server stopped")

Just run the code and go to localhost with your favorite browser.

If you get an error like this it means that another process is listening on port 80. Just use another like 8080, 8181, etc…

Traceback (most recent call last):
  File "/home/carles/Desktop/code/carles/json-realm-live/web_top.py", line 74, in <module>
    o_webserver = HTTPServer(("localhost", 80), WebServer)
  File "/usr/lib/python3.8/socketserver.py", line 452, in __init__
    self.server_bind()
  File "/usr/lib/python3.8/http/server.py", line 138, in server_bind
    socketserver.TCPServer.server_bind(self)
  File "/usr/lib/python3.8/socketserver.py", line 466, in server_bind
    self.socket.bind(self.server_address)
PermissionError: [Errno 13] Permission denied

And you will see the requests coming:

2021-10-09 10:47:46 Server started
127.0.0.1 - - [13/Oct/2021 10:47:48] "GET / HTTP/1.1" 200 -
2021-10-09 10:47:48 /
127.0.0.1 - - [13/Oct/2021 11:25:24] "GET / HTTP/1.1" 200 -
2021-10-09 11:25:24 /

So instead of using top, you can use ctop.py :)

Just replace the command by:

s_command = "ctop.py -b -n=1 --rows=30 --columns=200"

You can also create a Dockerfile very easily and run this in a Container.

News of the blog 2021-08-16

  • I completed my ZFS on Ubuntu 20.04 LTS book.
    I had an error in an actual hard drive so I added a Troubleshooting section explaining how I fixed it.
  • I paused for a while the advance of my book Python: basic exercises for beginners, as my colleague Michela is translating it to Italian. She is a great Engineer and I cannot be more happy of having her help.
  • I added a new article about how to create a simple web Star Wars game using Flask.
    As always, I use Docker and a Dockerfile to automate the deployment, so you can test it without messing with your local system.
    The code is very simple and easy to understand.
mysql> UPDATE wp_options set option_value='blog.carlesmateo.local' WHERE option_name='siteurl';
Query OK, 1 row affected (0.02 sec)
Rows matched: 1 Changed: 1 Warnings: 0

This way I set an entry in /etc/hosts and I can do all the tests I want.

  • I added a new section to the blog, is a link where you can see all the articles published, ordered by number of views.
    /posts_and_views.php

Is in the main page, just after the recommended articles.
Here you can see the source code.

  • I removed the Categories:
    • Storage
      • ZFS
  • In favor of:
    • Hardware
      • Storage
        • ZFS
  • So the articles with Categories in the group deleted were reassigned the Categories in the second group.
  • Visually:
    • I removed some annoying lines from the Quick Selection access.
      They came from inherited CSS properties from my WordPress, long time customized, and I created new styles for this section.
    • I adjusted the line-height to avoid separation between lines being too much.
  • I added a link in the section of Other Engineering Blogs that I like, to the great https://github.com/lesterchan site, author of many super cool WordPress plugins.