Databases on Abel World

Docker master slave MySQL replication

Tue, 11 Dec 2018 09:45:37 +0200

Docker master slave mysql replication can be a bit intimidating, but the basics are actually quite easy, just a bit of a laborious work. As of this example I will use docker swarm. for that I assume you have docker already installed fresh on the machine. My example uses CentOS 7.6, but should be similar on other systems like ubuntu. Enjoy the post!

Get the mysql image:

docker pull percona:5.7

Create a few dirs to hold the structure:

Two separate folders for master and slave.
The cnf directory has the configuration files for mysql
The data directory has the volume of mysql structural data.
The folders called mysql, performance schema and sys should NOT be created. those are done by MySQL server on start.

MySQL slave master switch

Sat, 01 Jul 2017 17:15:11 +0200

MySQL slave to master switch is an operation required in a few situations. Sometimes master dies and you need to make DB available as soon as possible. In this case if the DB is reasonably big then restoring from backup might take to long. Also keep present that slave has a current copy of data, you might have new data after the last backup that you can not afford to lose. Some other common situations where you might require such a procedure is when you want to upgrade your MySQL servers. For instance from Percona 5.6 to Percona 5.7. Also this will help to avoid long downtime.

Notice: if you have classic master slave replication some downtime is unavoidable, there are different setups that can be done to achieve having a cluster that does not stop working if you take the master offline, but this is NOT the objective of this post.

this post is some what related to another recent post; Mysql DB server OS change / replacement or distro upgrade; study case

Ok, let’s stop the chitchat and let’s get some stuff done.

Mysql DB server OS change / replacement or distro upgrade; study case

Tue, 27 Jun 2017 09:35:17 +0200

Mysql DB server OS change:

Mysql DB server OS change might be required in different situations, but for those who do not know what I am talking about, let me start by explaining what this is and why you might need it in some situations. Just to serve as an example; let say you are renting a few Virtial Machine Server from X IDC or cloud provider. This cloud provider gave you an a distribution that in 2013 had 4 years of support and everything was cool, you installed you systems. Now is 2017 and you need an upgrade. Let me give more details.

You are running a web environment with load balancers, web-server, and 2- Mysql DB servers Master and slave replication, etc. Your application needs High availability and you can not afford to have a lot of downtime. Your system is running fine, but last month you got a notification that the EOL (End of life) of your distribution is in 2 months. You also you noticed that your Percona MySQL DB 5.5 has a few limitations that you want to resolve by upgrading toPercona MySQL DB 5.6 or 5.7. So this is the perfect opportunity to upgrade the system and not remain with a legacy OS that will lose support soon. So now you know all you need to know and you are decided to go with progress and make a difference with the change.

You contact your provider about upgrading your system. They reply with a link (URL) to their FAQ saying that they do not support system upgrade. Then you start reading about it and notice that many virtualization services providers do not really support the upgrade. So you can not just du apt-get dist-upgrade. Not that you can not try, but you will likely not succeed, own experience here long ago when I was young and stupid. Maybe your provider supports it, but you might have grown fond of some other distribution over time and you want to change let say from Debian to Redhat or vise-versa, change of company policy, etc. So reason for wanting to change are many.

Hosting network services services and websites basics

Thu, 12 Nov 2015 19:47:53 +0200

Hosting network services and websites or blogs like this one is now a days a regular task of anyone who want to conduct a successful business. This is non written a requirement for many other activities as well. If you are not an ICT professional and you have a website or need to deploy some services in your business and you wander where to store them and how. Then this article is for you.

More people than you might think want to get a server at their home or office and host their own websites and services locally. I am not 100% against this type of solutions, but the truth is the all the odds now a days are against it unless you have a particularly special need to have it locally. Let see what are the drawbacks.

Website development projects

Thu, 05 Nov 2015 19:39:13 +0200

Having a good Website is very important for modern business, so some of the last projects that I have been doing lately are related to website development. For instance one of them were done for Team Engineers (Pty) Ltd, Botswana. They already had a website, that needed a platform easier to edit and manage as well as a new look to certain extend and some interactive features. Team Engineers defines itself as follows.

“TEAM Engineers (PTY) Ltd. is a specialist prefabricated accommodation solutions provider. Since its establishment in 1997, TEAM has gone from strength to strength not only in capacity and knowledge, but also in diversity of the product range and our level of service.”

They are the biggest company in Botswana in the business with a very well gained reputation of great quality solutions, for diverse purposes like: accommodation, mining facilities, schools, hospitals, offices, housing, etc. Please check out the next slider for some basic details about the look of the current website.

Web hosting administration software free alternative.

Thu, 29 Jan 2015 10:35:17 +0200

Hi, have engaged myself on a quest to look for an administration panel for my customers hosting. I want a good one to have it as an alternative to

Web Hosting

cPanel, the truth is that every day I like the cPanel project less and the free alternatives are getting better. So unless you are committed for some MAJOR reason to cPanel I would not recommend it any more. Use any other GLP like thing from out there, if the problem is support get better support from one of the communities.

Update multiple tables from a column; MySQL

Tue, 27 Jan 2015 12:03:13 +0200

Update multiple tables from a column is something that does not happen very often. Personally I never had to do it. I came across this question from a friend. He is programming something, and he had the following situation:

field_data_body
+----------+---------------------+
| entry_id | body_value |
+----------+---------------------+
| 1009 | content |
+----------+---------------------+
| 1020 | |
+----------+---------------------+
| 1025 | more content |
+----------+---------------------+


i_posts
+------+---------------+
| id | html |
+------+---------------+
| 1009 | |
+------+---------------+
| 1020 | | 
+------+---------------+
| 1025 | | 
+------+---------------+

From this two tables he wanted to get i_posts updated with information from field_data_body’s body_value field. In other words write this:

LDAP linux configuration and install from source

Sun, 11 Jan 2015 21:37:35 +0200

Hi, if you want to configure LDAP (OpenLDAP) properly and you have never done it, I advise you to read a lot of

LDAP tree

nonsense out there that people write on blogs like mine, before actually trying. After reading a lot of that the you can try, and let me tell you a secret, the best documentation is the one that they provide on their own website, just that sometimes that one is a bit complex to understand.

Well fist the fist, my LDAP version 2.4 never worked installing from repositories on Debian 7. How unable am I or how silly… I don’t know. Bot it did not work as it use to do with earlier versions. I was unable to set the user, password, domain and those initial things using the installer package.deb and dpkg-reconfigure. So I decided immediately that if I am losing the power of having a repository because of this nonsense, then I do not need them any more. I am going to compile the package myself from source. I tried so… but I struggled with the ./configure options. I could not fins the proper ones. and this error report thread gave me the clue to be able to follow the LDAP manual.

After reading this manual I ended up with a file that contains this:

GLPI ticket system & Inventory solution a very viable solution

Tue, 06 Jan 2015 16:00:10 +0200

Team work organization solutions with GLPI

Have a problem to organize team work? have problem to document and follow performance? You do not have satisfactory the statistics about the work done! Have you ever had problems to find simple reports like who is the best worker of the month? Have problems planning resources for the department? Do not know how many computers and other equipment are in the network?

You can use GLPI to solve all those problems. I have a few years of experience maintaining these type of servers for different environment and customer needs. lso I decided to write this post and share some of the things that you can get with GLPI. The main features of GLPI are:

Inventory of computers, peripherals, network printers and associated components through an interface with OCS Inventory or FusionInventory.

Management of issues on many environments through creation of tickets, management of tickets, assignment, tickets scheduling, etc.

Licenses management (ITIL compliant)

Assignment of equipment by geographical area to users and groups

Management of business and financial information (purchase, guarantee and extension, damping)

Equipment status management

Management of applications for assistance of all types of equipment inventory

Interface to allow the user to file a support ticket

Business management, contracts, documents related to inventory items

Equipment booking

Management of a Frequently-Asked Questions (FAQ).

Report generator: hardware, network or interventions (support).

Multilingual support with 45 languages available.

Fleet management system with Symfony 2, php, MySQL; TeamERP Transport

Tue, 15 Apr 2014 10:27:55 +0200

TeamERP Transport Symfony 2

Updated on 2014-05-19.

I have been programming for one week and I have a transport module that can work for different situation now. I have released it as a MIT license so that any one can use it or do what ever they want with it. My objective is to create a truly free ERP system. But you have to start somewhere, and I have decided that the transport module could be a nice module. This module is a software that can be used to record transport expenses and to follow the cars movements. It’s not a tracking systems. but in the future I an planning to integrate it with one of this projects. the project was developed with Symfony 2; php, MySQL.

In this document I described the Symfony 2 development process for the development of a Fleet management system. I started from scratch to what I currently have and it took me one week of work. The project is going to be used by a friend of mine company. All the iterations and problems found along a real life development process will be posted here. This document is about the Transport module and the objective is not to have a book of how to use Symfony 2 and develop. But a guide of what has been done with Symfony 2 and the current state of the module. More like a diary of notes and the documentation of this development. You can also find some other Symfony 2 development material here.

GLPI for technical support, the free tickets System.

Sat, 09 Nov 2013 10:34:41 +0200

GLPI Statistic Charts

GLPI is a free Tickets System distributed under GNU/GPL license. But When do you need a ticket system like this? This is one of the biggest challenges of the technical support companies or technical support teams. If they have to deal with many customers and the response times are critical. To be able to track, follow and organize the work of the different technicians that are supposed to do the actual job. In this scenario the paper work always becomes a challenge, accessibility, loose of information, spell and writing errors, individual and collective statistics, reporting, etc.

Useful Notes as a solution to punctual problems

Fri, 08 Nov 2013 18:20:21 +0200

I tend to forget where I find the solution for my problem very often, so I will start recording some of the solutions that I find for my different problems, if any one find this list some how interesting or useful in the future please consider leaving a comment or suggest other useful information that you have found in internet: