Graphical vi-vim Cheat Sheet and Tutorial

Graphical vi-vim Cheat Sheet and Tutorial is yet another attempt to explain and visualize Vim commands to the editor’s new users.

This is a single page describing the full vi/vim input model, the function of all keys, and all major features. You can see it as a compressed vi/vim manual.

Zabbix : No more flapping. Define triggers the smart way.

No more flapping. Define triggers the smart way.” is a very useful article from the Zabbix Weblog on how to setup sensible, flapping-aware triggers in Zabbix.

I’m sure every single person on this planet has a limit to how many up and down notifications he can receive …

16 Linux Books and Videos for System Administrator

Having knowledge of Linux is essential for any system administration, middleware, web engineer job.

Linux is used almost everywhere in production or a non-production environment. There are thousands of article, book, video training to explore and learn but that would be time-consuming.

Instead, you can follow one or two related books or online training.

The following learning materials cover a large number of Linux Administration tasks from beginning to expert level. So pick the one suits you.

Source: 16 Linux Books and Videos for System Administrator

Deploy and Maintain Redmine, the Right Way

Jens Krämer wrote this nice guide to deploying and maintaining Redmine the right way.  This is basically a combination of the official Redmine documentation with a variety of guides on deploying and running a generic Ruby on Rails application.  The solution is rightfully focusing on git, combining the upstream patches with your own changes.  And given that this is “the right way”, you don’t even have to have any of your own changes.  Just being prepared for some is good.

Once you’ve setup the proper environment, you can further automate the deployment of Redmine with Capistrano.  If you don’t use Capistrano for whatever reason – no worries, the process is easily adoptable to whatever build/deploy tool you are using.

Making “Push on Green” a Reality

Making “Push on Green” a Reality is an insider look at how Google handles continuous deployment.  Very few teams and companies need to deal with such level of complexity, but the overall principals still probably apply.

Updating production software is a process that may require dozens, if not hundreds, of steps. These include creating and testing new code, building new binaries and packages, associating the packages with a versioned release, updating the jobs in production datacenters, possibly modifying database schemata, and testing and verifying the results. There are boxes to check and approvals to seek, and the more automated the process, the easier it becomes. When releases can be made faster, it is possible to release more often, and, organizationally, one becomes less afraid to “release early, release often”. And that’s what we describe in this article—making rollouts as easy and as automated as possible. When a “green” condition is detected, we can more quickly perform a new rollout. Humans are still needed somewhere in the loop, but we strive to reduce the purely mechanical toil they need to perform.

Linux Inside – A book-in-progress about the Linux kernel and its internals

Linux Inside” is a book-in-progress about the Linux kernel and its internals.  You can read it online or download as a PDF.  It’s also available in several languages.  Some of the things that you’ll find inside are:

  • The boot process
  • Initialization
  • Interrupts
  • System calls
  • Timers and time management
  • Synchronization primitives
  • Memory management
  • SMP
  • Data structures in the Linux kernel
  • … and more.

 

A Practical Guide to Linux Commands, Editors, and Shell Programming

I came across the second edition of the Prentice Hall’s “A Practical Guide to Linux Commands, Editors, and Shell Programming” by Mark G. Sobell (original link).  This is a rather lengthy book at just over 1,000 pages, covering everything from history of Linux and basic commands, all the way to bash, Perl, and sed, and how things work both on the inside and outside.

It’s probably not one of those books to read from cover to cover, but quite handy to keep as a reference and flip a few pages once in a while.

HTTPS on Stack Overflow: The End of a Long Road

Way too often I hear rants from random people (unfortunately, many of them are also from the IT industry, with the deep understanding of the underlying issues) complaining about why company X or product Y doesn’t implement this or that feature.  As someone who has been involved a dozens, if not hundreds, of projects, I pretty much always can think of a number of reasons why even seemingly the simplest of features aren’t implemented for years.  These can vary from business side of things – insufficient budgets, strategic goals, and the like – to technical, such as architectural limitations, insufficient expertise, insufficient resources, etc.

One of the recent frequent rant that keeps coming up is “Why don’t they just enable HTTPS?”.  Again, as someone being involved in HTTPS setup for several different environments I can think of a number of reasons why.  SSL certificates used to cost money and were quite cumbersome to install until very recently.  Thanks to Let’s Encrypt effort, SSL certificates are now free and quite easy to issue and renew.  But that’s only part of the problem.  Enabling HTTPS requires infrastructural changes, and the more complex your infrastructure, the more changes are needed.  Just think of a few points here – web server configuration (especially when you have multiple web servers, with varied software (Apache, Nginx, IIS) and varied versions of that software), load balancers, web application firewalls, reverse proxies, caching servers, and so on.

Apart from the infrastructural changes, HTTPS often needs changes on the application level.  Caching, cookies, headers, making sure that all your resources are HTTPS-only, redirects, and the like.

All of the above issues are multiplied by a gadzillion, when your project is publicly available, used by tonnes of people, and provides embeddable content or APIs to third-party (hello, backward compatibility).

This is not to mention that HTTPS itself is a complex subject, not well understood by even the most experienced system administrators and developers.  There are different protocols and versions (SSL vs. TLS), cipher suites, handshakes, and protocol details.  Just have a look at the variety of checks and the report length done by Qualys’ SSL Labs Server Test.  Even giants like Google, who employ thousands of smart people, can’t get it all right.

But for some reason, people either don’t know or prefer to ignore all this complexities, and whine and cry anyway.

Recently, Stack Overflow – a well known collection of sites on a variety of technical subjects, has completed the migration to HTTPS everywhere.  These are also people with a lot of knowledge and expertise and with access to all the information.  Just have a look at their long way, which took not months, but years: HTTPS on Stack Overflow: The End of a Long Road.

Today, we deployed HTTPS by default on Stack Overflow. All traffic is now redirected to https:// and Google links will change over the next few weeks. The activation of this is quite literally flipping a switch (feature flag), but getting to that point has taken years of work. As of now, HTTPS is the default on all Q&A websites.

We’ve been rolling it out across the Stack Exchange network for the past 2 months. Stack Overflow is the last site, and by far the largest. This is a huge milestone for us, but by no means the end. There’s still more work to do, which we’ll get to. But the end is finally in sight, hooray!

So next time you are about to start crying about somebody not having feature X or Y, just give it a minute first.  Try to imagine what goes on on the other side.  You aren’t the only one with low budgets, pressing deadlines, insufficient knowledge, bad colleagues and horrible bosses…

Introducing Moby Project: a new open-source project to advance the software containerization movement

Docker Blog is introducing the Moby Project:

The Moby Project is a new open-source project to advance the software containerization movement and help the ecosystem take containers mainstream. It provides a library of components, a framework for assembling them into custom container-based systems and a place for all container enthusiasts to experiment and exchange ideas.

This just had to happen, given the nature of the Open Source and the importance of the container technology for the modern infrastructure.