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One-line Tree in Python

Using Python's built-in defaultdict we can easily define a tree data structure:

def tree(): return defaultdict(tree)

That's it!

Remove unused packages on Raspberry Pi

(this is worth looking at http://www.stefan-seelmann.de/wiki/rasperrypi-homeserver, which is basically this:

apt-get purge --auto-remove scratch debian-reference-en dillo idle3 python3-tk idle python-pygame python-tk lightdm gnome-themes-standard gnome-icon-theme raspberrypi-artwork gvfs-backends gvfs-fuse desktop-base lxpolkit netsurf-gtk zenity xdg-utils mupdf gtk2-engines alsa-utils  lxde lxtask menu-xdg gksu midori xserver-xorg xinit xserver-xorg-video-fbdev libraspberrypi-dev libraspberrypi-doc dbus-x11 libx11-6 libx11-data libx11-xcb1 x11-common x11-utils lxde-icon-theme gconf-service gconf2-common

)

Warning: this will probably break something. If you need sound, don't remove the "alsa" packages

sudo apt-get --yes purge xserver-common x11-xfs-utils x11-xserver-utils xinit libsmbclient blt gvfs gvfs-backends gvfs-daemons gvfs-fuse idle idle-python2.7 idle-python3.2 idle3 libaudio2 libice6 liblightdm-gobject-1-0 libobrender27 libpulse0 libqt4-svg libqt

Update HISTORY.md
Commit the changes:

git add HISTORY.md
git commit -m "Changelog for upcoming release 0.1.1."

Update version number (can also be minor or major)

bumpversion patch

Create PDF files from Markdown sources in OSX

When [Markdown][markdown] appeared more than 10 years ago, it aimed to make it easier to express ideas in an easy-to-write plain text format. It offers a simple syntax that takes the writer focus away from the formatting, thus giving her time to focus on the actual content.

The market abunds of editors to be used for help with markdown. After a few attempts, I settled to Sublime and its browser preview plugin, which work great for me and have a small memory footprint to accomplish that. To pass the results around to other people, less technical, a markdown file and a bunch of images is not the best approach, so converting it to a more robust format like PDF seems like a much better choice.

[Pandoc][pandoc] is the swiss-army knife of converting documents between various formats. While being able to deal with heavy-weight formats like docx and epub, we will need it for the more lightweight markdown. To be able to generate PDF files, we need LaTeX. On OSX, the s

This script can help you find and remove unused AWS snapshots and volumes.

There is hardcoded list of regions that it searches, adjust the value to suit your needs.

Use snapshot.py snapshot-report to generate report.csv containing information about all snapshots.

snapshot.py snapshot-cleanup lets you interactively delete snapshot if it finds it is referencing unexisting resources.

./snapshots.py --help

CPU: percentage of limit

A lot of people land when trying to find out how to calculate CPU usage metric correctly in prometheus, myself included! So I'll post what I eventually ended up using as I think it's still a little difficult trying to tie together all the snippets of info here and elsewhere.

This is specific to k8s and containers that have CPU limits set.

To show CPU usage as a percentage of the limit given to the container, this is the Prometheus query we used to create nice graphs in Grafana:

sum(rate(container_cpu_usage_seconds_total{name!~".*prometheus.*", image!="", container_name!="POD"}[5m])) by (pod_name, container_name) /

	# ~/.tmux.conf
	#
	# See the following files:
	#
	# /opt/local/share/doc/tmux/t-williams.conf
	# /opt/local/share/doc/tmux/screen-keys.conf
	# /opt/local/share/doc/tmux/vim-keys.conf
	#
	# URLs to read:
	#

	<project name="{{ name }}" default="help" basedir=".">

	<property name="username" value="{{ username }}"/>
	<property name="host" value="{{ host }}"/>
	<property name="dir" value="/srv/{{ path }}/"/>

	<tstamp>
	<format property="TODAY_UK" pattern="yyyyMMddhhmmss" locale="en,UK"/>
	</tstamp>

	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	Version 2, December 2004

	Copyright (C) 2011 Jed Schmidt <http://jed.is>

	Everyone is permitted to copy and distribute verbatim or modified
	copies of this license document, and changing it is allowed as long
	as the name is changed.

	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE

	bind-key C-b send-prefix
	bind-key C-o rotate-window
	bind-key C-z suspend-client
	bind-key Space next-layout
	bind-key ! break-pane
	bind-key " split-window
	bind-key # list-buffers
	bind-key $ command-prompt -I #S "rename-session '%%'"
	bind-key % split-window -h
	bind-key & confirm-before -p "kill-window #W? (y/n)" kill-window