Cobus Bernard cobusbernard

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

General rules

Follow standard conventions.
Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
Boy scout rule. Leave the campground cleaner than you found it.
Always find root cause. Always look for the root cause of a problem.

Design rules

If you want to check whether a node run_list includes a specific role (upon expansion), then you could use role? method on the Node object:

node.role?('name')

Alternatively, you can see whether either would work for you:

node.roles.include?('name')

node.run_list?('role[name]')

Spurred by recent events (https://news.ycombinator.com/item?id=8244700), this is a quick set of jotted-down thoughts about the state of "Semantic" Versioning, and why we should be fighting the good fight against it.

For a long time in the history of software, version numbers indicated the relative progress and change in a given piece of software. A major release (1.x.x) was major, a minor release (x.1.x) was minor, and a patch release was just a small patch. You could evaluate a given piece of software by name + version, and get a feeling for how far away version 2.0.1 was from version 2.8.0.

But Semantic Versioning (henceforth, SemVer), as specified at http://semver.org/, changes this to prioritize a mechanistic understanding of a codebase over a human one. Any "breaking" change to the software must be accompanied with a new major version number. It's alright for robots, but bad for us.

SemVer tries to compress a huge amount of information — the nature of the change, the percentage of users that wil

This example is based on having a cascading setup, where you have a single master, a single "primary" slave, and cascading slaves which are being replicated from the primary slave. For an example of this setup, check out http://bartek.im/blog/2012/12/04/postgresql-92-streaming-primer.html

On the existing master, if accessible, stop postgres.

$ sudo service postgresql stop

And better to be safe than sorry. We can't have two masters running. (I only use this in an automated script. If you're doing this manually, you'd know if it was shutoff)

$ kill -9 `sudo cat /var/lib/postgresql/9.2/main/postmaster.pid | head -n 1` &> /dev/null

	#
	# Google Apps Script
	#

	#
	# To set a "cron" trigger:
	# Edit > Current project's triggers > Add a new Trigger > "Main" function > Every 5 minutes
	#

	var GECKOBOARD_TOKEN_API = "";

	{
	"variables": {
	"aws_access_key": "", // This helps me connect to AWS
	"aws_secret_key": ""
	},
	"builders": [{
	"type": "amazon-ebs",
	"access_key": "{{user `aws_access_key`}}",
	"secret_key": "{{user `aws_secret_key`}}",
	"region": "us-east-1",

	# knife cheat

	## Search Examples

	knife search "name:ip*"
	knife search "platform:ubuntu*"
	knife search "platform:*" -a macaddress
	knife search "platform:ubuntu*" -a uptime
	knife search "platform:ubuntu*" -a virtualization.system
	knife search "platform:ubuntu*" -a network.default_gateway

	-- This Source Code Form is subject to the terms of the Mozilla Public
	-- License, v. 2.0. If a copy of the MPL was not distributed with this
	-- file, You can obtain one at http://mozilla.org/MPL/2.0/.

	require "math"
	require "string"
	local alert = require "alert"

	local message_variable = read_config("message_variable") or error("must specify a 'message_variable'")
	local max_items = read_config("max_items") or 25000

	openssl rsa -in ~/.ssh/id_rsa -outform pem > id_rsa.pem
	chmod 600 id_rsa.pem