coding – Ad Astra Per Aspera

Minicloud: the Free OpenPower cloud

I recently got access to the Minicloud, a Free OpenPower Cloud hosted by Unicamp, one of the most prominent universities in Brazil. This cloud is a good way to ensure that your application provides good support for the Power architecture.

Having access to this cloud, I can help ensure that some of the projects I am interested about can be ran and supported on this architecture. Additionally, it offers me a Power environment to test the messaging-related packages I maintain on Fedora and CentOS – entirely on my free time.

To start with this cloud, I decided to go big and deploy Maestro there. Having only 4Gb, it means that I need to adjust very well the resources of my VMs so that I can maximize the usability of the cloud environment. I will write some posts about this.

The other project that I am interested in playing with in the Minicloud is Paho C, the MQTT client from Eclipse Foundation. As the Fedora maintainer for the package, having access to this environment means that I have a personal environment where I can ensure the quality of the packages.

Messaging performance: tips, tricks and tools

Today I gave a talk entitled “Messaging Performance: tips, tricks and tools” at the DevConf.cz 2017 in Brno. For those interested in the subject, I have made the slides available here.

The talk itself should also be available soon on the DevConf.cz channel on youtube.

Otavio’s must-watch linux.conf.au talks

I compiled a list of 8 talks from linux.conf.au 2017 that interested me. You can watch it here or just click play on the embedded video below:

EOY 2016 links

Some links about interesting things I’ve read or watched by the end of 2016. Further comments are provided on each item of the list.

Single file libraries: open source libraries with minimal dependencies.
The sorry state of programming world as the end of 2016 AD: food for though regarding how most of development is done nowadays.
Find my Phone: what happens when your phone is stolen.
PayPal Cuts Costs 10x With Open Source CI: self descriptive.
Learning to Read x86 Assembly: self descriptive.
Json-c tutorial: how to manipulate json in C.
The 101 of ELF Binaries on Linux: Understanding and Analysis: self descriptive.
How the Linux kernel knows it’s running in a Virtual Machine: self descriptive.
Stack Overflow: The Architecture – 2016 Edition: self descriptive.
AMQP 1.0 in Azure Service Bus and Event Hubs protocol guide: a detailed explanation abou AMQP 1.0.
10 Tips for C and C++ Performance Improvement Code Optimization: simple optimization tips.
Light Weight Protocol: Critical Implications: a talk about MQTT and security.
Modern C: a book about modern C programming.

SonarQube database migration: MariaDB 5.5 to MySQL 5.7

Newer versions of SonarQube have stopped supporting MariaDB and you may need to switch to MySQL instead. While I’d rather use MariaDB, I understand that it is not within the supported matrix. Therefore I am documenting the steps here. The steps are focused on RHEL 7 (they probably would work on Centos 7 as well, but I did not test it).

Before start with this process, shutdown your SonarQube instance as well as any other analysis that may access the database.

The first step is to use mysqldump to create a backup of your MariaDB database:

mysqldump sonar > sonar.sql

1	mysqldump sonar > sonar.sql

After the backup is complete, shutdown and disable your MariaDB instance:

systemctl stop mariadb ; systemctl disable mariadb

1	systemctl stop mariadb ; systemctl disable mariadb

Then install MySQL 5.7 from Software Collections. The process is documented on this page. These steps are for 5.6, however, you can just replace 56 with 57 in all the steps and the result is the same.

With the new MySQL 5.7 installed and running, create the database:

mysql -u root

1	mysql -u root

In the MySQL sheel recreate the database with the same credentials and permissions as the old one:

CREATE USER '[old username]'@'localhost' IDENTIFIED BY '[old password]';
GRANT ALL PRIVILEGES ON *.* TO '[old username]'@'localhost' WITH GRANT OPTION;
CREATE USER '[old username]'@'%' IDENTIFIED BY '[old password]';
GRANT ALL PRIVILEGES ON *.* TO '[old username]'@'%' WITH GRANT OPTION;

CREATE USER '[old username]'@'localhost' IDENTIFIED BY '[old password]';

GRANT ALL PRIVILEGES ON *.* TO '[old username]'@'localhost' WITH GRANT OPTION;

CREATE USER '[old username]'@'%' IDENTIFIED BY '[old password]';

GRANT ALL PRIVILEGES ON *.* TO '[old username]'@'%' WITH GRANT OPTION;

Then you can recover the backup into the new MySQL 5.7 instance:

mysqldump sonar < sonar.sql

1	mysqldump sonar < sonar.sql

Now you can go to your SonarQube server and start it.