Things to learn about Linux

Julia Evans has this amazing list of things to learn about Linux.  I think, it doesn’t matter how new or experienced you are with the operating system, you’ll find a few points in this list that you either know nothing about or know very little.

Personally, I’ve been using and administrating Linux systems for almost two decades now, and my own knowledge of the things on that list is either very limited or not existing.  Sure, I know about pipes and signals, but even with basic things like permissions there are some tricky questions that I’m not sure I can get right on the first go.

Some of the topics mentioned are simple and straight-forward and will only need a few minutes or a couple of hours to get up to speed with.  Others – are huge areas which might take years, if not decades (like networking, for example).

I look forward to Julia’s drawings covering some of these.

 

Migrating to PHP 7

PHP 7.0.0 has been released for a year now.  I wasn’t in a rush to migrate to it, but with all the cool features and performance optimization, it’s definitely something I wanted to look into rather sooner than later.

It turns out that I’ve done my first PHP 7 migration a week ago, when I upgraded my laptop to Fedora 25.  Yup, that’s right.  It’s a bit embarrassing, but I have been developing on PHP 7 for a week without even noticing it.

$ php --version
PHP 7.0.13 (cli) (built: Nov 9 2016 07:29:28) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
with Xdebug v2.4.1, Copyright (c) 2002-2016, by Derick Rethans

I think that was due to a few things:

  • It’s been quite a busy week, so my attention was all over the place.
  • PHP 7 backward compatibility is pretty awesome.  There are only a few things that need fixing in the older code bases, but if you haven’t been living under a rock for the last few years, you probably have nothing to change or worry about.
  • Most of the code I’m working on runs through TravisCI builds, which are executed on both PHP 5.6 and PHP 7.  Since we had this for a while now, most, if not all, of our code is PHP 7 compatible.

The absolute lack of any issues for the last week, related to this upgrade, is encouraging.  Now I will probably try to upgrade our servers sooner than later.

With that, I’ll go back to the wonderful and exciting world of PHP, leaving you to decide whether I’m very serious or very sarcastic…

 

Amazon Lightsail – virtual private servers made easy

Amazon announced a new service – Amazon Lightsail – virtual private servers made easy, starting at $5 per month.

pricing

This is basically a much simplified setup of a few of their services, such as Amazon EC2, Amazon EIP, Amazon AIM, Amazon EBS, Amazon Route 53, and a few others.  For those, who don’t want to figure out all the intricacies of the infrastructure setup, just pick a VPC, click a few buttons and be ready to go, whether you want a plain operating system, or an application (like WordPress) already installed.

It’s an interesting move into the lower level web and VPS hosting.  I don’t think all the hosting companies will survive this, but for those that will do, the changes are coming, I think.

Julia’s Drawings on Programming

Julia Evans, who blogs about her programming endeavors, now also draws simple, note-like sketches on a variety of the computer and programming related subjects.  Those are great as kick memory refreshers or reminders for “I wanted to learn more about that” kind of things.  Here’s her take on pipes, for example:

pipes

Worth an RSS subscription!

EPEL : the effort behind the scenes

Catching up with recent news, I came across this blog post by Stephen John Smoogen in Fedora People, where he explains the reason for the recent disappearance of the Puppet package from the Extra Packages for Enterprise Linux (EPEL 6) repository:

This week various people using EPEL on RHEL and CentOS 6 have found that the puppet package is no longer provided by EPEL. The reason for this is due to the way EPEL packages are built and kept inside the repository. A package needs a sponsor so that we can hopefully get bug fixes and security updates to it. In the case of puppet this package is sponsored by the user kanarip. However, most packages aren’t whole pieces, they rely on other software.. in this case the package puppet relies on a lot of different ruby gems of which one of them was called ruby-shadow. This package was orphaned 30 weeks ago and while it did have other people watching it, none of them took over the package.

[…]

Last week a large cleanup was done to clean out orphaned packages from EPEL which removed ruby-shadow. Once that was removed, then all of the other packages depending on ruby-shadow were also removed. Today various people reinstalling systems found puppet wasn’t around and came onto #epel to ask.. which seems to have gotten the packages responsored and hopefully they will be back in the EPEL release in a day or so.

This problem has been happening a lot lately. I think it shows quite a few problems with how EPEL is set up and managed. For this, I take responsibility as I said I would try to clean it up after FOSDEM 2016 and it is still happening.

Unpleasant annoyance that shouldn’t have happened, right?  Well, yes, maybe.

Software is a complex matter, whether you are designing, developing, testing, or distributing it.  So things do go wrong sometimes.  And that was something I wanted to focus on for a second.

Forget the actual designing, developing, testing and documenting the software.  Forget all the infrastructure behind such a vital part of the Linux ecosystem as EPEL.  Just think of this single issue for a moment.  Once again:

A package needs a sponsor so that we can hopefully get bug fixes and security updates to it.

So what, I hear you say.  Well, let’s take a closer look.  EPEL provides packages for multiple versions of the distribution, hardware platforms and so on.  Let’s just look at the EPEL 6 for x86_64 (to keep things simple).  That looks like a lot of packages, doesn’t it?.  How many? At the time of this writing, from a random mirror that I got:

wget -q -O - http://download.fedoraproject.org/pub/epel/6/x86_64/ | grep -c 'unknown.gif'
12129

Yup. That’s 12,129 packages!  And each one of those has at least one developer behind it, to sponsor.  Some of those amazing people obviously maintain more than one package. Some packages are maintained by multiple people.  All of them are working hard behind the scenes for you and me to have an easy and stable access to a whole lot of software.  Here is a quote from the FAQ which is smoked and marinated in all that effort:

Software packages in EPEL are maintained on a voluntary basis. If you to want ensure that the packages you want remain available, get involved directly in the EPEL effort. More experienced maintainers help review your packages and you learn about packaging. If you can, get your packaging role included as part of your job description; EPEL has written a generic description that you can use as the basis for adding to a job description.

We do our best to make this a healthy project with many contributors who take care of the packages in the repository, and the repository as a whole, for all releases until RHEL closes support for the distribution version the packages were built for. That is ten years after release (currently) — a long time frame, and we know a lot can happen in ten years. Your participation is vital for the success of this project.

I don’t know about you, but for me, this is absolutely mind-blowing.  So I just wanted to take this opportunity to say thank you to all the brilliant people behind the scenes, who are often invisible, yet indispensable for the continuous success of Open Source software in general, and Linux in particular.

You guys rock!

Fedora 25

I’ve just upgraded my laptop to Fedora 25.  The upgrade process was a breeze (as per instructions from this article):

sudo su -
dnf upgrade --refresh
dnf install dnf-plugin-system-upgrade
dnf system-upgrade download --releasever=25
dnf system-upgrade reboot

About 2,500 packages (1 GB and some) were downloaded in about 40 minutes (yeah, our Internet connection could use a boost). Then rebooted and the upgraded kicked in. It took about another 40 minutes to run the process (I should get myself an SSD-based laptop next time).

The only thing I had to fix after the upgrade was the kmod-wl package, which provides the drivers for my wireless interface. Another reboot later all was good.

There were no major visual changes (I’m using MATE Desktop), but something felt a bit different.  After focusing on the differences for a few minutes, I think it’s the fonts.  Something is better, sharper, more polished.

Other than that, all is pretty much the same.  I’ll need to use it for a while to see if I can spot any changes.  Hopefully, at least a flickering issue that I got after some upgrade during the Fedora 24 life span is fixed now.  It was weird.  A particular application window would start to flick and refresh until clicked again.  Never figured out what it was. :)

SQL Server in a Fedora Docker Container

MS SQL Server and Docker

It’s a well known fact that I am not the greatest fan of Microsoft and their technologies.  I’ve been bitten many a time through the years.  And not even them becoming a Platinum Partner in the Linux Foundation can change my attitude towards them.  It’s just been too much pain, and scars, and tears, and sweat.

But the way life is, once in a while, I just have to work with or around them.  Recently, for example, at work, we’ve done a project that just had to use MS SQL Server and there was no way to get around it.  Gladly, I managed to find just the right image on the Amazon AWS Marketplace, and spin a new EC2 instance for testing.  The local development was difficult, but at least we had a place to test stuff before sending it off to the customer.

If such a need arises in the future, I think I’ll give the MS SQL for Linux a try.  And that’s when this article from Fedora Magazine might come in handy.  MS SQL + Docker + Fedora.  Hmm.

Using Ansible to bootstrap an Amazon EC2 instance

This article – “Using Ansible to Bootstrap My Work Environment Part 4” is pure gold for anyone trying to figure out all the moving parts needed to automate the provisioning and configuration of the Amazon EC2 instance with Ansible.

Sure, some bits are easier than the other, but it takes time to go from one step to another.  In this article, you have everything you need, including the provisioning Ansible playbook and variables, cloud-init bits, and more.

I’ve printed and laminated my copy.  It’s on the wall now.  It will provide me with countless hours of joy during the upcoming Christmas season.

Monitoring the monitoring : keeping Zabbix server service up

After our recent MySQL migrations, I started getting a weird issue – Zabbix server process was crashing periodically (several times a day).

8395:20161109:175408.023 [Z3005] query failed: [2013] Lost connection to MySQL server during query [begin;]
8395:20161109:175408.024 [Z3001] connection to database 'zabbix_database_name_here' failed: [2003] Can't connect to MySQL server on 'zabbix_database_host_here' (111)
8395:20161109:175408.024 Got signal [signal:11(SIGSEGV),reason:1,refaddr:(nil)]. Crashing ...

Digging around for a bit, it seems like a widely reported issue, related Zabbix server using the same database connection as one of its agents is monitoring (here is an example bug report).

Not having enough time to troubleshoot and fix it properly, I decided for the time being to use another monitoring tool – monit – to keep an eye on the Zabbix server process and restart it, if it’s down.  After “yum install monit“, the following was dropped into /etc/monit.d/zabbix:

check process zabbix_server with pidfile /var/run/zabbix/zabbix_server.pid
    start program = "/sbin/service zabbix-server start" with timeout 60 seconds
    stop program = "/sbin/service zabbix-server stop"

Start the monit service, make sure it also starts at boot, and watch it in action via the /var/log/monit:

[UTC Nov 20 20:49:18] error    : 'zabbix_server' process is not running
[UTC Nov 20 20:49:18] info     : 'zabbix_server' trying to restart
[UTC Nov 20 20:49:18] info     : 'zabbix_server' start: /sbin/service
[UTC Nov 20 20:50:19] info     : 'zabbix_server' process is running with pid 28941

The chances of both systems failing at once are slim, so I think this will buy me some time.