https://dmsimard.com/categories/tutorial/ Recent content in tutorial on System Administration, Hosting, Cloud and technologies in between Hugo -- gohugo.io en-us Tue, 18 Jul 2017 00:00:00 +0000 https://dmsimard.com/2017/07/18/patching-ansible-with-ansible/ Tue, 18 Jul 2017 00:00:00 +0000 https://dmsimard.com/2017/07/18/patching-ansible-with-ansible/ (Edit: See at the end) I can’t get enough of this Ansible thing, it’s great and makes my life easier. Sometimes there’s this little awesome feature that is in a pull request or has already landed in the development branch. You can’t wait to use but it won’t be shipped until the next release of Ansible.. and sometimes that takes a while. What do you do in the meantime ? https://dmsimard.com/2017/05/10/limiting-the-amount-of-concurrent-asynchronous-tasks-in-ansible/ Wed, 10 May 2017 00:00:00 +0000 https://dmsimard.com/2017/05/10/limiting-the-amount-of-concurrent-asynchronous-tasks-in-ansible/ Ansible is known to be good at running things in the order you write them and that’s why it’s awesome for orchestration. However, I have a use case where I have several similar and long-running tasks to run that do not need to run sequentially. Ansible provides a way to run tasks asynchronously and later recover their result. The problem The problem is that Ansible doesn’t provide a way to limit the amount of concurrent tasks run asynchronously. https://dmsimard.com/2014/09/28/finding-the-right-openstack-provider/ Sun, 28 Sep 2014 00:00:00 +0000 https://dmsimard.com/2014/09/28/finding-the-right-openstack-provider/ How to find a great Openstack provider. Isn’t that a good question ? The Openstack foundation thinks so, too. That’s why it announced the release of the Openstack Marketplace at the last Openstack summit in Atlanta. It’s definitely a step in the right direction towards helping users find trustworthy providers of Openstack services. To be listed, providers must meet basic requirements that are verified by the foundation. The great thing is that the marketplace is not limited to public or private cloud offerings, you’ll also be able to find offers for training or consulting, too. https://dmsimard.com/2014/05/18/hours-of-free-ccna-training-video-material/ Sun, 18 May 2014 00:00:00 +0000 https://dmsimard.com/2014/05/18/hours-of-free-ccna-training-video-material/ About a year ago, Andrew Crouthamel launched a kickstarter to produce a free series of videos about the CCNA Cisco certification. Andrew is a Cisco Certified Academy Instructor and he’s actually been teaching CCNA courses so he’s knowledgeable about the training material. I remember the kickstarter pretty well because the pilot video reminded me a bit of the video series about Reddit’s architecture. I didn’t think much of it at the time. https://dmsimard.com/2014/03/23/tac-reverse-output-in-linux/ Sun, 23 Mar 2014 00:00:00 +0000 https://dmsimard.com/2014/03/23/tac-reverse-output-in-linux/ You probably use cat everyday. Did you know that tac existed ? It’s the reverse of cat! (no, really). It allows to reverse the contents of a file or, if used with a pipe, the output of the initial command. Let’s see how it works by sorting a directory listing by timestamp… # ls -alt total 4492 drwxrwsr-t 2 owner group 712704 Mar 23 10:32 . -rw-r--r-- 1 owner group 225 Mar 21 16:26 tmp. https://dmsimard.com/2014/02/15/quick-hiera-tips/ Sat, 15 Feb 2014 00:00:00 +0000 https://dmsimard.com/2014/02/15/quick-hiera-tips/ If you use Puppet at all, you should be using Hiera if you’re not already ! Hiera is a powerful key/value lookup tool for configuration data for puppet. Here’s some quick tips on how you can use it. Puppet 3 ships with Hiera by default so that’s a good start… Using Hiera For the first example I’ll be showing in this post, I’ll be using the following simplistic files and configuration: https://dmsimard.com/2013/12/26/updating-xenserver-eject-all-the-dvds/ Thu, 26 Dec 2013 00:00:00 +0000 https://dmsimard.com/2013/12/26/updating-xenserver-eject-all-the-dvds/ I was preparing an update for a Xenserver pool with over 100 VMs on it and I forgot that when you apply patches on Xenserver nodes, you need to eject images/ISO/DVDs from the virtual machines. I start looking through some of the VMs, eject a few manually through Xencenter and think “There must be an easier way..". Thankfully, the folks at Citrix made a simple and efficient bash script that loops through the VMs, verifies if there is a mounted media and allows you to eject it. https://dmsimard.com/2013/12/02/fixing-mysql-fatal-error-1236/ Mon, 02 Dec 2013 00:00:00 +0000 https://dmsimard.com/2013/12/02/fixing-mysql-fatal-error-1236/ It happens. You have a Master -> Slave MySQL replication and your master crashes for a reason or another. You’re worried about bringing the master back online as soon as possible. When you finally get it back up, you notice the slave is stopped, complaining about a dreaded error that looks a bit like this: The binlog file got corrupted when the master database server crashed. Restoring a backup won’t save you, nor will re-importing the database. https://dmsimard.com/2013/11/26/how-to-contribute-to-puppet-openstack/ Tue, 26 Nov 2013 00:00:00 +0000 https://dmsimard.com/2013/11/26/how-to-contribute-to-puppet-openstack/ Thanks to the hard work of the puppet-openstack community, Puppet was the preferred method of deployment for Openstack in the latest Openstack User Survey. If you’d like to join in on the fun and contribute, read on ! First things first, a bit of context: Openstack is a modular cloud orchestration platform, self-described as “Open source software for building private and public clouds”. puppet-openstack is a Stackforge project that centralizes the development of puppet modules related to Openstack.