Code Ghar

Build container images in Kubernetes with kaniko

Hamza Sheikh — Fri, 08 Feb 2019 07:22:14 GMT

Building container images on Kubernetes is a desirable capability. It opens new avenues of continuous integration (CI). We are no longer tied to using something like Jenkins to schedule our CI build jobs. We can use the scheduling proficiency of Kubernetes instead.

Apply Patch to OpenBSD

Hamza Sheikh — Fri, 27 Jul 2018 18:34:33 GMT

Do a search and you'll find very little official comprehensive tutorial-type documentation on how to apply one or more patches to OpenBSD. The information is spread among different manual pages and such.

As described in Security updates FAQ:

While applying fixes from the errata page typically requires less time
than a CVS checkout/update and rebuild, there is no universal set of
instructions to follow. Sometimes you must patch and recompile one
application, sometimes more.

Here's how I patched an OpenBSD 6.3 system running on Cubox i4-pro with 32GB MicroSD card in July of 2018.

Terraform Recreates EC2 Instances on Every Plan

Hamza Sheikh — Thu, 24 May 2018 00:14:25 GMT

Have you ever seen an issue where Terraform recreates AWS EC2 instances on every plan and apply?

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OpenBSD on Ubiquiti USG

Hamza Sheikh — Thu, 05 Apr 2018 05:40:19 GMT

Ubiquiti Unifi Security Gateway (USG) is a great device to run at the edge of a home network. It becomes even better when it's running OpenBSD. This guide documents how to setup such a gateway. There are accompanying git repos to somewhat automate the process as well.

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Package Python in a Snap

Hamza Sheikh — Tue, 09 Jan 2018 04:20:24 GMT

Getting newer versions of Python on long term support releases of Linux distributions, such as Ubuntu or CentOS, without interfering with the system Python can be pretty involved. Doing it on multiple instances is even harder. Fortunately, it is possible and quite easy by using snapd.

How to Use Python Virtualenv

Hamza Sheikh — Wed, 01 Nov 2017 01:43:30 GMT

A Python virtualenv is an isolated directory that serves as the root filesystem (kind of) for an installation of Python. In simpler terms, Python is installed in a non-privileged directory by a regular user. Anything installed for that instance of Python does not affect any other Python instance installed on the system.

This guide will show you how each instance of a Python interpreter differs from others and how to use this to your advantage.

Introduction to Makefile

Hamza Sheikh — Fri, 27 Oct 2017 02:59:26 GMT

Are you in the same boat as I was only a few weeks ago? That is, does writing a Makefile intimidates you beyond belief? Fear not! Makefiles appear to be insurmountable (and some of the complicated ones really are) but if you start with simple steps, they are really not that difficult.

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Use select() in Python Socket Programming at Your Own Risk

Hamza Sheikh — Fri, 07 Jul 2017 21:38:20 GMT

When one reads the Python Socket Programming HOWTO, non-blocking sockets are mentioned along with select. This is a tale of when select can cause issues if you're not careful.

OpenBSD Network Gateway on EdgeRouter Lite

Hamza Sheikh — Tue, 06 Jun 2017 22:22:59 GMT

EdgeRouter Lite is a great device to run at the edge of a home network. It becomes even better when it's running OpenBSD. This guide documents how to setup such a gateway. There are accompanying git repos to somewhat automate the process as well.

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Essential pkgsrc - The Missing Mini Handbook

Hamza Sheikh — Sat, 25 Mar 2017 19:29:16 GMT

pkgsrc is a cross operating system package manager. It supports -- among many others -- NetBSD, Minix, SmartOS, Linux, and macOS. I like it because of this portability. It also has the additional, and I would say the best, benefit of being installed in the home directory and run completely without needing root access. I also like that I don't have to depend on binary packages built by someone else, say Joyent, although there's absolutely nothing wrong with it. Finally, it provides a large number of different packages. I have never encountered a package that I needed but was not available. In short pkgsrc is a portable, featureful, and flexible package manager. What's not to like?

pkgsrc can sometimes be a little behind native package managers, such as MacPorts on macOS, but it catches up quickly. For my use case -- getting access to multiple versions of Python -- it works well enough if I closely follow its trunk branch.

There's generally good and detailed documentation available for pkgsrc but an introductory guide that pulled in some essential starter information was lacking. This guide fills that void by making it easy to get started with pkgsrc and learn about some of its core concepts. Thus, I dubbed it the mini handbook or the missing starter handbook.

FreeBSD Network Gateway on EdgeRouter Lite

Hamza Sheikh — Mon, 02 Jan 2017 03:35:14 GMT

EdgeRouter Lite is a great device to run at the edge of a home network. It becomes even better when it's running FreeBSD. This guide documents how to setup such a gateway. There are accompanying git repos to somewhat automate the process as well.

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Shell Scripting Cookbook

Hamza Sheikh — Thu, 10 Nov 2016 19:36:14 GMT

Tips I have learned on how to do things in shell scripts.

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Use Fixtures Effectively in PyTest

Hamza Sheikh — Tue, 30 Aug 2016 03:43:48 GMT

Fixtures are a great feature of PyTest but using them can be tricky. I found them to be very useful when all important environment logic resides in them and tests use a consistent interface without regard to how the environment is actually set up.

Install Latest Python on CentOS 7

Hamza Sheikh — Wed, 13 Apr 2016 05:07:07 GMT

There are many options to install newer Python on CentOS, including building from source, installing from EPEL, installing from Software Collections (SCL), installing third party rpm package, etc. These all work to some degree of success. I had a different use case and could not find a pre-built rpm package to fit it.

My use case had these restraints:

Install newer Python alongside the default system version
Install multiple Python versions simultaneously
Install the latest release from upstream Python project not just the latest release from a repository (repo)
Do not build from source unless absolutely necessary

Requiring Encryption in Apache Qpid

Hamza Sheikh — Tue, 05 Apr 2016 06:12:48 GMT

I configured requiring encryption in Apache Qpid (C++ broker) by adding the following line to /etc/qpid/qpidd.conf file and restarting the broker

require-encryption=yes

Later when I used qpid-stat I got an error message

$ qpid-stat -q -b user@password/localhost:5672
Failed: AuthenticationFailure - Error in sasl_client_start (-4) SASL(-4): no mechanism available

After following a mailing list post to a JIRA to a Review Board entry I found that when broker requires a secure TLS connection then the connection string must use amqps protocol instead of amqp like so

$ qpid-stat -q -b amqps://user@password/localhost:5672

I was using version 0.34 of both broker and client.

Build Bootable FreeBSD Image for Raspberry Pi 2 with Vagrant, Crochet, and Salt

Hamza Sheikh — Sat, 30 Jan 2016 05:47:29 GMT

An issue in FreeBSD 11-CURRENT - where make buildworld fails when run on RPi2 - prompted an investigation on automating the creation of bootable FreeBSD images from 11-CURRENT on a Mac OS X machine.

In an ideal situation, a build process can be kicked off at any time to produce an image that can be written to a Micro SD card for the RPi2 to boot from.

RaspBSD on Raspberry Pi 2 Model B

Hamza Sheikh — Wed, 14 Oct 2015 04:52:03 GMT

I bought a Raspberry Pi 2 Model B from CanaKit to install and learn FreeBSD. Fortunately for me (and you) RaspBSD is available.

I found at one point that using an 8GB Micro SD card caused me headaches as I ran out of disk space at some points. I would recommend buying a bigger card.

This guide was created using OS X 10.10 (Yosemite) as the "client". All instructions assume:

Correct software installed on OS X
You know how to use Disk Utility and CLI
You have already assembled the Raspberry Pi (RPi) hardware (case, etc.)
WiFi USB adapter is not connected initially (it's configured later)
Ethernet, HDMI, keyboard, mouse are connected to Raspberry Pi
USB to TTL serial cable is available for use (I bought this one: http://www.amazon.com/gp/product/B00QT7LQ88)
Drivers from http://prolificusa.com/pl-2303hx-drivers/

WARNING: This is a "living document" and will be updated as I learn from my mistakes. There may be a lot of errors in this doc so all the standard disclaimers apply.

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Configure Atom as git Editor

Hamza Sheikh — Tue, 06 Oct 2015 22:53:12 GMT

In Atom open the command palette (Shift-Command-p) and enter command Install Shell Commands.

Configure Atom as git's editor.

git config --global core.editor "atom --new-window --wait"

Now when you do git commit it should open a new Atom window for you to enter your commit message.

What is a Tight Loop?

Hamza Sheikh — Tue, 06 Oct 2015 22:28:16 GMT

One often hears about tight loops in the context of programming. I never really got what it meant. Until today.

A tight loop may be described as a loop that does very little work itself but has an impact on the performance of the larger program. For example, in an O(n) loop the faster it can execute each iteration the tighter it is.

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Python readline Bug

Hamza Sheikh — Tue, 06 Oct 2015 22:23:12 GMT

Problem

In the Python interpreter whenever I hit enter it would show a blank line without a prompt and I'd have to press enter again to see the prompt. When I exited the interpreter the terminal would not show anything I typed. Pressing the return key would show my shell prompt on the same line. Up arrow or down arrow keys did not make any difference. reset was a last resort.

For example,

Python 3.4.3 (default, Aug 26 2015, 18:29:14)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.56)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> abs(1-0)
>>> 1

>>> ^D>>>
~ $ ~ $ ~ $ reset

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FreeBSD Post Install Setup

Hamza Sheikh — Wed, 12 Aug 2015 00:28:43 GMT

FreeBSD Post Install Setup

After you have installed FreeBSD (10.1-RELEASE in my case) these steps will help you set it up for use. I'd recommend going through this guide and executing the sections in the order in which they appear here.

Disclaimer: I'm very new to FreeBSD so these are meant more for my notes than a canonical guide for others. Read the FreeBSD Handbook instead.

Get Started with GnuPG

Hamza Sheikh — Tue, 11 Aug 2015 18:41:39 GMT

Get Started with GnuPG

Install

I'll assume you'll want to use GnuPG v2.

If you're using Ubuntu install from the repos.

user@host:~$ sudo aptitude install gpgv2

You can also install from Nix package manager. It'll usually have newer versions available than the Ubuntu respos (especially if it's LTS).

user@host:~$ nix-env -i gnupg-2.1.1

WARNING: This is a "living document" and will be updated as I learn from my mistakes.

Generate Your Key Pair

You'll need a lot of entropy while generating a key pair. I don't know how much it helps but I run the following in a separate terminal window while I generate a key pair.

user@host:~$ dd if=/dev/urandom of=/dev/null

While the dd process is running, run the following in a different terminal window to generate your key pair.

user@host:~$ gpg2 --gen-key

You'll be asked for your real name and email address. This constructs an identity for you. Make sure to use your actual information here.

You will also be asked to provide a passphrase. Choose a secure passphrase and do not lose it. It's often recommended to keep a printed copy in a safe place, locked away from prying eyes.

Should Web Apps Go in /srv or /var/www?

Hamza Sheikh — Wed, 08 Apr 2015 04:43:02 GMT

Should Web Apps Go in /srv or /var/www?

Is it better to follow Debian's default webroot policy or FHS? Should I install my web apps in /srv or /var/www?

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Should Your Software Go in /usr/local or /opt?

Hamza Sheikh — Wed, 08 Apr 2015 04:39:27 GMT

Should Your Software Go in /usr/local or /opt?

As you try to install software from source or a locally built package, where do you install it? Is /usr/local the right path or does /opt make sense?

Install Kanboard on FreeBSD

Hamza Sheikh — Fri, 13 Mar 2015 17:06:06 GMT

Install Kanboard on FreeBSD

Read the Kanboard installation guide for updated information. This guide focuses on the FreeBSD, nginx, and Kanboard stack. It's tested on 10.1-RELEASE.

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