Docker Praxistraining für (Web) Entwickler

October 23 @ 09:00 – October 24 @ 16:00

Schulung / Training / Kurs / Seminar – 2 Tage remote

Das sich mit Docker auf sehr effiziente Weise Arbeitsumgebungen für Entwickler bereitstellen lassen hat sich bereits herumgesprochen. Wie eine solche Arbeitsumgebung aber auf dem eigenen Entwicklungsrechner effizient und zeitsparend aufgebaut und betrieben wird, lernen sie in diesem Kurs von Grund auf.

Das Praxisbeispiel führt Sie Schritt für Schritt hin zu einer vollwertigen Programmierumgebung für PHP Webprojekte, einem sogenannten LAMP Stack. Während Sie die Dienste Apache 2 HTTP Webserver mit PHP und einer MySQL Datenbank, sowie dem Administrationswerkzeug PhpMyAdmin über Docker Container erstellen, lernen Sie nebenher alle wichtigen Grundlagen zu Docker, um künftig auch anders gestaltete Entwicklungsumgebungen erstellen zu können.

Profitieren sie von den vielen Vorteilen die Ihnen Docker auch in den Entwickleralltag bringt. Gekapselte parallele Installationen die sich leicht aktualisieren lassen und zudem noch wetvolle Systemressourcen schonen. Nutzen Sie die eingesparte Zeit um sich mit den wirklich wichtigen Dingen beschäftigen zu können, dem programmieren.

Durchführungs-Garantie: der Kurs wird auch bei nur einem Teilenmenden durchgeführt

Kurs buchen: https://www.gfu.net/seminare-schulungen-kurse/open_source_sk62/docker-praxistraining-fuer-web-entwickler_s2665.html

Jeder Teilenmende erhält eine gedruckte Ausgabe des Buches: Marco Schulz, CI mit Jenkins, Rheinwerk, 2021

Sollten Sie zu den angebotenen Terminen nicht können, beziehungsweise für Ihr Team einen individuellen Termin wünschen, um beispielsweise in einer geschlossenen Runde auf konkrete Problemstellungen eingehen zu können, besteht die Möglichkeit zusätzliche außerplanmäßige Termine zu vereinbaren. Nutzen Sie bitte hierzu mein Kontaktformular unter der Angabe welchen Kurs Sie wünschen, mit Terminvorschlägen und der zu erwartenden Teilnehmerzahl.

Weitere Termine:

21.03 – 22.03.2024
20.06 – 21.06.2024

Git: Überblick für Entwickler

November 27 @ 09:00 – November 28 @ 16:00

Schulung / Training / Kurs / Seminar – 2 Tage remote

In dem Seminar “Git für Entwickler” erlernen Sie die Grundlagen und die Verwendung von Git, dem führenden Versionskontrollsystem für Softwareentwicklung. Git ist für fast alle Sprachen nutzbar und kostenlos verwendbar.

Durchführungs-Garantie: der Kurs wird auch bei nur einem Teilenmenden durchgeführt

Kurs buchen: https://www.gfu.net/seminare-schulungen-kurse/testmanagement_sk92/git-fuer-entwickler_s2556.html

Jeder Teilenmende erhält eine gedruckte Ausgabe des Buches: Marco Schulz, CI mit Jenkins, Rheinwerk, 2021

Weitere Termine:

22.02 – 23.02.2024
23.05 – 24.05.2024
23.09 -27.09.2024

Grazer Linux Tage 2022

April 23, 2022 All day

Heimnetz ohne Werbung mit AdGuard auf dem RaspberryPI

Leider ist von Minute 1:00 bis 2:10 kein Tonmitschnitt vorhanden 🙁 – einfach überspringen

Es gibt viele Projekte die sich für einen Raspberry PI eignen. Aus eigener Anwendung zeige ich wie man im Heimnetzwerk das Tool AdGuard in einem Docker Container zum laufen bringt, um damit die Werbung für alle im Netwerk verbundenen Geräte abstellt.

In diesem kleinen Workshop geht es darum auf einem Raspberry PI 4 mit einem Ubuntu Server Docker zum Laufen zu bekommen. Das ist aber der einfachste Schritt, denn dann geht es ans Eingemachte und wir fühlen den Netzwerkmöglichkeiten von Docker ein wenig auf den Zahn. Ein bischen SSH und Shell, ganiert mit Routerkonfiguration und vielen kleine praktischen Tipps runden den Talk ab.

Working with textfiles on the Linux shell

Posted on 2022-06-01 by Elmar Dott

Linux turns more and more to a popular operating system for IT professional. One of the reasons for this movement are the server solutions. Stability and low resource consuming are some of the important characteristics for this choice. May you already played around with a Microsoft Server you will miss the graphical Desktop in a Linux Server. After a login into a Linux Server you just see the command prompt is waiting for your inputs.

In this short article I introduce you some helpful Linux programs to work with files on the command line. This allows you to gather information, for example from log files. Before I start I’d like to recommend you a simple and powerful editor named joe.

Ctrl + C – Abort the current editing of a file without saving changes
Ctrl + KX – Exit the current editing and save the file
Ctrl + KF – Find text in the current file
Ctrl + V – Paste clipboard into document (CMD + V for Mac)
Ctrl + Y – Delete current line where cursor is

To install joe on an Debian based Linux distribution you just need to type:

sudo apt-get install joe

1. When you need to find content in a huge text file GREP will be your best friend. GREP allows you to search for text pattern in files.

gerp <pattern> file.log
    -n : number of lines that matches
    -i : case insensitive
    -v : invert matches
    -E : extended regex
    -c : count number of matches
    -l : find filenames that matches the pattern

Bash

2. When you need to analyze network packages NGREP is the tool of your choice.

ngrep -I file.pcap
    -d : specify the network interface
    -i : case insensitive
    -x : print in alternate hexdump
    -t : print timestamp
    -I : read a pcap file

Bash

3. When you need to see the changes between two versions of a file, DIFF will do the job.

diff version1.txt version2.txt
    -a : add
    -c : change
    -d : delete
     # : line numbers
     < : file 1
     > : file 2

Bash

4. Sometimes it is necessary to give an order to the entries in a file. SORT is gonna to help you with this task.

sort file.log 
     -o : write the result to a file
     -r : reverse order
     -n : numerical sort
     -k : sort by column
     -c : check if orderd
     -u : sort and remove
     -f : ignore case
     -h : human sort

Bash

5. If you have to replace Strings inside of a huge text, like find and replace you can do that with SED, the stream editor.

sed s/regex/replace/g
     -s : search
     -g : replace
     -d : delete
     -w : append to file
     -e : execute command
     -n : suppress output

Bash

6. Parsing fields using delimiters in text files can done by using CUT.

cut -d ":" -f 2 file.log
     -d : use the field delimiter
     -f : field numbers
     -c : specific characters position

Bash

7. The extraction of substrings who occurred just once in a text file you will reach with UNIQ.

uniq file.txt
     -c : count the numbers of duplicates
     -d : print duplicates
     -i : case insesitive

Bash

8. AWK is a programming language consider to manipulate data.

awk {print $2} file.log

Bash

How to reduce the size of a PDF document

Posted on 2022-05-01 by Elmar Dott

When you own a big collection of PDF files the used storage space can increasing quite high. Sometimes I own PDF documents with more than 100 MB. Well nowadays this storage capacities are not a big issue. But if you want to backup those files to other mediums like USB pen drives or a DVD it would be great to reduce the file size of you PDF collection.

Long a go I worked with a little scrip that allowed me to reduce the file size of a PDF document significantly. This script called a interactive tool called PDF Sam with some command line parameters. Unfortunately many years ago the software PDF Sam become with this option commercial, so I was needed a new solution.

Before I go closer to my approach I will discuss some basic information about what happens in the background. As first, when your PDF blew up to a huge file is the reason because of the included graphics. If you scanned you handwritten notes to save them in one single archive you should be aware that every scan is a image file. By default the PDF processor already optimize those files. This is why the file size almost don’t get reduced when you try to compress them by a tool like zip.

Scanned images can optimized before to include them to a PDF document by a graphic tool like Gimp. Actions you can perform are reduce the image quality and increase the contrast. Specially for scanned handwritten notes are this steps important. If the contrast is very low and maybe you plan to print those documents, it could happens they are not readable. Another problem in this case is that you can’t apply a text search over the document. A solution to this problem is the usage of an OCR tool to transform text in images back to real text.

We resume shortly the previous minds. When we try to reduce the file size of a PDF we need to reduce the quality of the included images. This can be done by reducing the amount of dots per inch (dpi). Be aware that after the compression the image is still readable. As long you do not plan to do a high quality print like a magazine or a book, nothing will get affected.

When we wanna reduce plenty PDF files in a short time we can’t do all those actions by hand. For instance we need an automated solution. To reach the goal it is important that the tool we use support the command line. The we can create a simple batch job to perform the task without any hands on.

We have several options to optimize the images inside a PDF. If it is a great idea to perform all options, depend on the purpose of the usage.

change the image file to the PNG format
reduce the graphic dimensions to the real printable area
reduce the DPI
change the image color profile to gray-scale

As Ubuntu Linux user I have all of the things I need already together. And now comes the part that I explain you my well working solution.

Ghostscript

GPL Ghostscript is used for PostScript/PDF preview and printing. Usually as a back-end to a program such as ghostview, it can display PostScript and PDF documents in an X11 environment.

If you don’t have Ghostscript installed on you system, you can do this very fast.

sudo apt-get update
sudo apt-get -y install ghostscript

Bash

Before you execute any script or command be aware you do not overwrite with the output the existing files. In the case something get wrong you loose all originals to try other options. Before you start to try out anything backup your files or generate the compressed PDF in a separate folder.

gs -sDEVICE=pdfwrite \
   -dCompatibilityLevel=1.4 \
   -dPDFSETTINGS=/default \
   -dNOPAUSE -dQUIET -dBATCH -dDetectDuplicateImages \
   -dCompressFonts=true \
   -r150 \
   -sOutputFile=output.pdf input.pdf

Bash

The important parameter is r150, which reduce the output resolution to 150 dpi. In the manage you can check for more parameters to compress the result more stronger. The given command you are able to place in a script, were its surrounded by a FOR loop to fetch all PDF files in a directory, to write them reduced in another directory.

The command I used for a original file with 260 MB and 640 pages. After the operation was done the size got reduced to around 36 MB. The shrunken file is almost 7 times smaller than the original. A huge different. As you can see in the screenshot, the quality of the pictures is almost identical.

As alternative, in the case you won’t come closer to the command line there is a online PDF compression tool in German and English language for free use available.

PDF Workbench

Linux Systems have many powerful tools to deal with PDF documents. For example the Libreoffice Suite have a button where you can generate for every document a proper PDF file. But sometimes you wish to create a PDF in the printing dialog of any other application in your system. With the cups PDF print driver you enable this functionality on your system.

sudo apt-get install printer-driver-cups-pdf

Bash

As I already explained, OCR allows you to extract from graphics text to make a document searchable. When you need to work with this type of software be aware that the result is good, but you cant avoid mistakes. Even when you perform an OCR on a scanned book page, you will find several mistakes. OCRFeeder is a free and very powerful solution for Linux systems.

Another powerful helper is the tool PDF Arranger which allows you to add or remove pages to an existing PDF. You are also able to change the order of the pages.

Resources

Installing NextCloud with Docker on a Linux Server

Posted on 2021-11-26 by Frank Vogt

For business it’s sometime important to have a central place where employees and clients are able to interact together. NextCloud is a simple and extendable PHP solution with a huge set of features you can host by yourself, to keep full control of your data. A classical Groupware ready for your own cloud.

If you want to install NextCloud on your own server you need as first a well working PHP installation with a HTTP Server like Apache. Also a Database Management System is mandatory. You can chose between MySQL, MariaDB and PostgreSQL servers. The classical way to install and configure all those components takes a lot of time and the maintenance is very difficult. To overcome all this we use a modern approach with the virtualization tool docker.

The system setup is as the following: Ubuntu x64 Server, PostgreSQL Database, pgAdmin DBMS Management and NextCloud.

Agenda

Docker Basics
Installing Docker on a Ubuntu server
prepare your database
putting all together and make it run
insights to operate NextCloud

Docker Container Instructions

# create network
docker network create -d bridge --subnet=172.18.0.0/16 service

# postures database server
docker run -d --name postgres --restart=always \
--net service --ip 172.18.0.2 \
-e POSTGRES_PASSWORD=s3cr3t \
-e PGPASSWORD=s3cr3t \
-v /home/ed/postgres/data:/var/lib/postgresql/data \
postgres:11.1

# copy files from container to host system
docker cp postgres:/var/lib/postgresql/data /home/ed/postgres

# pgAdmin administration tool
docker run -d --name pgadmin --restart=no \
-p 8004:80 --net services --ip 172.18.0.3 \
-e PGADMIN_DEFAULT_EMAIL=account@sample.com \
-e PGADMIN_DEFAULT_PASSWORD=s3cr3t \
dpage/pgadmin4:5.4

# nextcloud container
docker run -d --name nextcloud --restart=always \
-p 8080:80 --net services --ip 172.18.0.4 \
-v /home/ed/_TEMP_/nextcloud:/var/www/html \
-e POSTGRES_DB=nextcloud \
-e POSTGRES_USER=nextcloud \
-e POSTGRES_PASSWORD=nextcloud \
-e POSTGRES_HOST=172.18.0.2 \
nextcloud:22.2.0-apache

Bash

If you have any question feel free to leave a comment. May you need help to install and operate your own NextCloud installation secure, don’t hesitate to contact us by the contact form. In the case you like the video level a thumbs up and share it.

Resources

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Learn to walk with Docker and PostgreSQL

Posted on 2021-11-01 by Elmar Dott

After some years the virtualization tool Docker proofed it’s importance for the software industry. Usually when you hear something about virtualization you may could think this is something for administrators and will not effect me as a developer as much. But wait. You’re might not right. Because having some basic knowledge about Docker as a developer will helps you in your daily business.

Step 0: create a local bridged network

docker network create -d bridge --subnet=172.18.0.0/16 services

Bash

The name of the network is services an bind to the IP address range 172.18.0.0 to 172.18.0.255. You can proof the success yourself by typing:

docker network ls

Bash

An output like the one below should appear:

NETWORK ID     NAME       DRIVER    SCOPE
ac2f58175229   bridge     bridge    local
a01dc5513882   host       host      local
1d3d3ac42a40   none       null      local
82da585ee2df   services   bridge    local

Bash

The network step is important, because it defines a permanent connection, how applications need to establish a connect with the PostgreSQL DBMS. If you don’t do this Docker manage the IP address and when you run multiple containers on your machine the IP addresses could changed after a system reboot. This depends mostly on the order how the containers got started.

Step 1: create the container and initialize the database

docker run -d --name pg-dbms --restart=no \
--net services --ip 172.18.0.20 \
-e POSTGRES_PASSWORD=s3cr3t \
-e PGPASSWORD=s3cr3t \
postgres:11

Bash

If you wish that your PostgreSQL is always up after you restart your system, you should change the restart policy form no to always. The second line configure the network connection we had define in step 0. After you created the instance pg-dbms of your PostgreSQL 11 Docker image, you need to cheek if it was success. This you can do by the

docker ps -a

Bash

command. When your container is after around 30 seconds still running you did everything right.

Step 2: copy the initialized database directory to a local directory on your host system

docker cp pg-dbms:/var/lib/postgresql/data /home/ed/postgres

Bash

The biggest problem with the current container is, that all data will got lost, when you erase the container. This means wen need to find a way how to save this data permanently. The easiest way is to copy the data directory from your container to an directory to your host system. The copy command needs tow parameters source and destination. for the source you need to specify the container were you want to grab the files. in our case the container is named pg-dbms. The destination is a PostgreSQL folder in the home directory of the user ed. If you use Windows instead of Linux it works the same. Just adapt the directory path and try to avoid white-spaces. When the files appeared in the defined directory you’re done with this step.

Step 3: stop the current container

docker stop pg-dbms

Bash

In the case you wish to start a container, just replace the word stop for the word start. The container we created to grab the initial files for the PostgreSQL DBMS we don’t need no longer, so we can erase it, but to do that as first the running container have to be stopped.

Step 4: start the current container

docker start pg-dbms

Bash

After the container is stopped we are able to erase it.

Step 5: recreate the container with an external volume

docker run -d --name pg-dbms --restart=no \
--net services --ip 172.18.0.20 \
-e POSTGRES_PASSWORD=s3cr3t \
-e PGPASSWORD=s3cr3t \
-v /media/ed/memory/pg:/var/lib/postgresql/data \
postgres:11

Bash

Now we can link the directory with the exported initial database to a new created PostgreSQL container. that’s all. The big benefit of this activities is, that now every database we create in PostgreSQL and the data of this database is outside of the docker container on our local machine. This allows a much more simpler backup and prevent losing information when a container has to be updated.

If you have instead of PostgreSQL other images where you need to grab files to reuse them you can use this tutorial too. just adapt to the image and the paths you need. The procedure is almost the same. If you like to get to know more facts about Docker you can watch also my video Docker Basics in less then 10 Minutes. In the case you like this short tutorial share it with your friends and colleagues. To stay informed don’t forget to subscribe to my newsletter.

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Docker Basics in less than 10 minutes

Posted on 2019-08-30 by Elmar Dott

This short tutorial covers the most fundamental steps to use docker in your development tool chain. After we introduced the basic theory, we will learn how to install docker on a Linux OS (Ubuntu Mate). When this is done we have a short walk through to download an image and instantiate the container. The example use the official PHP 7.3 image with an Apache 2 HTTP Server.

InPerson (remote) Training’s (Courses) /

Maven for Developer

Docker for Developers

DevOps Praxistraining

Wind of Change – a journey to Linux

Posted on 2017-11-11 by Elmar Dott

1989 was a historic year not just for Germany, it was for the whole world, when the Berlin wall teared down. A few months before, many people had wished that this event happen. But no one imagined it will become true. And even no person had in mind that everything goes so fast. Even me. Grew up on the side were we wished to touch the “always more green grass” of our neighbors. The Scorpions captured the spirit of the time with a song “Wind of change”. The unofficial hymn for the reunion of Germany.

Before I continue I need to clarify that this post will not mention anything from the Apple universe. Till today I never owned or used any Apple device. Why? Because there is no reason for me.

Conference Talks – Linux Tage

Linux TageSimilar to me it was with the strong dominance of Microsoft Windows as Operation System when I went into those computer things. Never I thought there is coming for me a time without Windows. Windows XP I had loved, after they fixed some heavy problems by Service Pack 1. Also Windows 7 an OS I really was liked to use and never I thought about a change. Really I always defended my Windows OS till this time. Because it was a really good system. But some years ago I changed my opinion – dramatically. Another wind of change. Let me give a brief history about decisions and experiences.

Everything began as I bought my Microsoft Surface 3 Pro with Windows 8.1 OS. In the beginning I was happy with the compact system and the performance. Very portable. A very important fact for me, because I travel a lot. I toked it also to my pilgrimage to Spain on the Camino de Santiago, to write my blog posts whit it. Unfortunately in the last week in Portugal the screen got broken. I was only be able to use it with external mouse. So I was forced to send the device to the Microsoft support. For a very shameless amount, close to a new buy – I got a replacement device with Windows 10. In between I also installed on my ThinkPad 510p Windows 10. I had felt like back in the year 2000 with my old Fujitsu Siemens Desktop and Windows Millennium. Almost every 3 months a re-installation of the whole system was necessary, because the update had broke the system. The most of my time I had spend to sit in front of my machine and wait that my Win 10 system got done whit the updates. During the updates, Windows 10 performance goes dramatically down and the system was not usable. If the device have more than 6 months no internet connection, it also close to impossible to turn on and start work with it. But this is not the whole drama. Every mayor update is breaking the customized configuration. Apps of the MS store already was deleted appeared again, additional language settings get broken and deactivated unwanted features was activated again. Another point is when you haven’t enough disk space for the Windows 10 update. This costs a lot of pain and frustrations. Till today the situation is not really changed. By the way Ubuntu Mate can also be run on a Microsoft Surface 3 PRO device.

The best you are be able to do with a Surface 3 PRO and its Windows 10 installation.

After I decided to run away from the Windows OS, I was needed to chose my new operation system. Well Linux! But which distribution? Usually in my job I only got experience with server and not by desktop systems. I remind me to my first SUSE Linux experiences in the early 2000. I think it was the Version 7 or something. I bought it in a store, because it came with a printed documentation and the download of more tha a Gigabyte with my 56k modem was not an option. Some years later I was worked with Ubuntu and Fedora. In the beginning Ubuntu I was not wanted to use for my change, because of the Unity engine. The first installation of Fedora was needed a lot of hands on to establish services like Dropbox and Skype. I was in search for a system I can code with it. For this requirements many persons recommended Debian. But Debian is more for experienced user and for the most people get first time in touch with Linux not an good advice. After some investigations I found Ubuntu Mate. A Gnome Desktop based on Debian whit a huge software repository. This was sounding perfect for my necessities. ANd its still today the system of my choice.

After I installed Ubuntu Mate on my machine I really liked it from the first moment. Fast and simple installation, excellent documentation and all application I was needed was there. Because of my travels I bought some years ago an Asus ZenBook UX and I run also Ubuntu from the first unboxing on it. Always when people see my system they are surprised because everything looks like a iBook, but is much better.

The change to Linux Ubuntu Mate was much easier than I expected. With some small tricks a re-installation of the whole system takes me now less than 2 hours. The main concept is always clean and backuped the bash history file. Then I be able to rerun all needed commands for installation and configuration. Some of the applications like my favorite IDE Apache NetBeans, I backuped the configuration settings. The prefix of the filename is always the date when I perform the settings export. For example the NetBeans backup file is named as 2017-03-31_NetBeans. Those backups I do currently manually and not scripted. The time to develop a full automatism takes me in the moment too much time and the services I have to backup are not so much. For this reason is a manual action sufficient. Typical services are e-mail, SFTP, Browser favorites and so on as part of my manual backup procedure.

Since Firefox changed his API 2018 a very useful tool for export and import passwords is not available any more. To avoid the usage of a cloud service you should not trust to store all account passwords online, I decided to use the crypto tool KeePass. After I add all my web accounts to this tool the storage of the passwords is also more secure. With the browser plugin the accounts can be shared between all popular browsers like Firefox, Chrome and Opera. The KeePass file wiht my stored passwords is automatically included into my backup. The only important procedure of password storing is to keep the password database up to date.

One thing I was used heavily on Windows was the Portable Apps ecosystem. My strategy was to have a independent installation of many well configured services for work I just need to include to my current system. Something like this exist also in Linux. Just without the Portable App environment. My preference is always download the ZIP version of a software which not needs an installation. This I store on a second partition. In the case of a virgin OS setup the partition just need to linked back to the OS and its done. The strategy to deal whit an separate disk partition offers also a high flexibility, we can use for another step, virtualization.

I don’t want to remind myself how much time I spended in my life to configure development services like web server and database. For this problem is Docker now the solution of my choice. Each service is in an own image and the data got linked from a directory into the container. Also the configuration. Start and stop of the service is a simple command and the host system stays clean. Tryouts of service updates are very easily and complete conflict free. A rollback can performed every time by deleting the virtualization container.

The biggest change was from MS Office to Libre Office. Well with the functionality of Libre Office I already was fluent. The problem was all the Presentations and and Word documents I had. If you tried to open those files in both office applications the formatting getting crazy. To avoid this problem, I had find out it is often just a problem of the fonts. I decided to download from google a free and nice looking font. This I installed on the old Windows machine to convert all my office document away from MS Office.

My resume after some years of Linux usage, today I can say absolutely honest I do not miss anything. Of course I have to admit, I do not play games. After some hours every day working on a computer I prefer to move back into reality to meet friends and family. Its nice to explore places during my travels or simply read a book. With Linux I have a great performance of my hardware and as of now I did got any issue with drivers. All my Hardware is still working under Ubuntu Mate Linux well as I expect. With Linux instead of WIndows I save a lot of lifetime and frustrations.