Let's once again improve Ansible. Well, this won't work without getting into sources.
Using kconfig for own projects
4 min
Intro
Every Linux professional write scripts. Someеimes light, linear. Sometimes complex script with functions and libs(yes, you can write your bash-library for use in other scripts).
But some of the scripts need a configuration file to work. For instance, I wrote a script that builds the ubuntu image for pxe, and I need to change the build process without build-script changes. The best way to resolve this task is to add configuration files.
Porting packages to buildroot using the Zabbix example
16 min
Tutorial
The basics of porting
Originally, Buildroot offers a limited number of packages. It makes sense — there is everything you need, but any other packages can be added.
To add a package, create 2 description files, an optional checksum file, and add a link to the package in the general package list. There are hooks at different stages of the build. At the same time, Buildroot can recognize the needed type of packages:
Safe-enough linux server, a quick security tuning
10 min
Tutorial
The case: You fire up a professionally prepared Linux image at a cloud platform provider (Amazon, DO, Google, Azure, etc.) and it will run a kind of production level service moderately exposed to hacking attacks (non-targeted, non-advanced threats).
What would be the standard quick security related tuning to configure before you install the meat?
release: 2005, Ubuntu + CentOS (supposed to work with Amazon Linux, Fedora, Debian, RHEL as well)
How I fix cups-printing in Buildroot
7 min
Intro
Like I said earlier in previos articles, Buildroot is a great system for embedded Linux development. But sometimes strange things can happen.
Once upon a workday, I got the following task: add printing system in firmware (Kraftway terminal Linux next generation). Ok, so I had to add cups + cups filter and to build firmware. I set a postscript-printer and got an error "Filter failed". Trivial tasks turned into serious work.
In this article, I wrote my own way of solving this problem. It may be useful for other developers and IT-specialist and, also, for a deeper understanding of the Buildroot.
If you are a Buildroot beginner, I recommend reading my previous articles.
Update 1 may 2020
Revisioned versions of this patches applied to master.
buildroot — my own experience with multi-platform distro creation
5 min
Introduction
In my previous article (Monitor linux) I wrote, what is this distro and how it works. Now i will write how to do it. It's may be interesting for everyone, who want to study buildroot.
Target goals
The result we get from article is the following:
- Firmware (non-volatile image with restorable config)
- Easy management via web-interface
- Cross-platform (qemu x86_64, arm-based SBC like rasberry 4, beagle bone black and asus tinker board)
- Support without extra effort
Monitor linux — cross platform firmware with zabbix server
4 min
About
This is small cross-platform linux-distro with zabbix server. It's a simple way to deploy powerful monitoring system on ARM platfornms and x86_64.
Worked as firmware (non-changeable systemd image with config files), have web-interface for system management like network settings, password and other.
Who is interested
- System admins/engineers who need to fast deploy of zabbix server.
- Everyone, who want to deploy zabbix on ARM.
- Enthusiasts
Fast and effective work in command line
9 min
Translation
There are a lot of command line tips and trics in the internet. Most of them discribe the trivials like "learn the hotkeys" or "sudo !! will run previous command with sudo". Instead of that, I will tell you what to do when you have already learned the hotkeys and know about sudo !!.
Down the Rabbit Hole: A Story of One varnishreload Error — part 1
8 min
After hitting the keyboard buttons for the past 20 minutes, as if he was typing for his life, ghostinushanka turns to me with a half-mad look in his eyes and a sly smile, “Dude, I think I got it.
Look at this†— as he points to one of the characters on screen — “I bet my red hat that if we add what I’ve just sent you here†— as he points to another place in the code — “there will be no error anymore.â€
Slightly puzzled and tired I modify the sed expression we’ve been figuring out for some time now, save the file and run systemctl varnish reload. Error message gone…
“Those emails I’ve exchanged with the candidate,†my colleague continues, as his smile changes to a wide and genuine grin, “It suddenly struck me that this is the very same exact problem!â€
12.3 million of concurrent WebSockets
19 min
Recovery Mode
One thing about WebSockets is that you need a lot of resources on the client's side to generate high enough load for the server to actually eat up all the CPU resources.
There are several challenges you have to overcome because the WebSockets protocol is more CPU demanding on the client's side than on the server's side. At the same time you need a lot of RAM to store information about open connections if you have millions of them.
I've been lucky enough to get a couple of new servers for a limited period of time at my disposal for the hardware "burnout" tests. So I decided to use my Lua Application Server — LAppS to do both jobs: test the hardware and perform the LAppS high load tests.
Checking rdesktop and xrdp with PVS-Studio
6 min
This is the second post in our series of articles about the results of checking open-source software working with the RDP protocol. Today we are going to take a look at the rdesktop client and xrdp server.
Using Linux Kernel Sequence Files
6 min
A characteristic feature of modern programming is the use of the global network as a source of reference information, in particular, a source of patterns for solving unknown or little-known problems for a specific programmer. Such an approach saves a lot of time and often gives quite qualitative results. However, the solutions laid out in the network although usually correct, do not always take into account all the subtleties of solving a problem, which leads to the appearance in the source code of sections that usually work correctly, but under not quite standard circumstances become sources of unpleasant surprises.
Consider the topic of using sequence files in the Linux kernel, such files are considered to be the most convenient mechanism for printing from kernel mode. But in practice, using them correctly is much more difficult than you would think.
A lot of materials on this topic are available online. The best is the source code of the kernel itself which has quite detailed comments. The problem with this source of information is its volume. If you do not know exactly what to look for, it is better if you only have limited time, not to try at all. For me, when I became interested in the topic, Google provided several seemingly excellent sources of information relating to my search: the famous book The Linux Kernel Module Programming Guide and a series of articles by Rob Day. These sources are not new, but very solid.
Consider the topic of using sequence files in the Linux kernel, such files are considered to be the most convenient mechanism for printing from kernel mode. But in practice, using them correctly is much more difficult than you would think.
A lot of materials on this topic are available online. The best is the source code of the kernel itself which has quite detailed comments. The problem with this source of information is its volume. If you do not know exactly what to look for, it is better if you only have limited time, not to try at all. For me, when I became interested in the topic, Google provided several seemingly excellent sources of information relating to my search: the famous book The Linux Kernel Module Programming Guide and a series of articles by Rob Day. These sources are not new, but very solid.
Checking FreeRDP with PVS-Studio
10 min
FreeRDP is an open-source implementation of the Remote Desktop Protocol (RDP), a proprietary protocol by Microsoft. The project supports multiple platforms, including Windows, Linux, macOS, and even iOS and Android. We chose it to be the first project analyzed with the static code analyzer PVS-Studio for a series of articles about the checks of RDP-clients.
Generating multi-brand multi-platform icons with Sketch and a Node.js script — Part #2
16 min
This is the second part of a post about the creation of a pipeline that can take a Sketch file and export all the icons included in the file, in different formats, for different platforms, with the possibility of AB testing each icon.
You can read the first part of the post here.
The Sketch files, with all the icons collected, styled and properly named, were ready. Now it was time to start writing the code.
Suffice to say, the process was very much a trial and error: after the important initial code core, developed by my team lead Nikhil Verma (who set the script foundations), I went through an incremental process that required at least three phases of refactoring and quite a few revisions. For this reason, I won’t go into too much detail on how the script was developed, but rather focus on how the script works today, in its final shape.