Erki Esken erkiesken

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Description

This simple script will take a picture of a whiteboard and use parts of the ImageMagick library with sane defaults to clean it up tremendously.

The script is here:

#!/bin/bash
convert "$1" -morphology Convolve DoG:15,100,0 -negate -normalize -blur 0x1 -channel RBG -level 60%,91%,0.1 "$2"

Results

a simple git branching model

This is a very simple git workflow. It (and variants) is in use by many people. I settled on it after using it very effectively at Athena. GitHub does something similar; Zach Holman mentioned it in this talk.

The gist

Proposal for Extending Express Apps

Creating npm packages which extend the functionality of Express apps has become a major thing we've been doing. There are several approaches we can take, from messing with the Express object prototypes, to creating a function in which an express app is passed in. After trying the former, I'm now a fan of the latter.

The Issues with Extending Express

Extending the Express object prototypes has issues. The running Node.js process may have multiple versions of express, and in order to extend the prototypes you need to require('express'). This means that you might get a different express module instance than the one the main app is created from.

Both approaches suffer from extending something more than once. Similar to how there may be multiple version of express in the running Node.js process, there can also be multiple copies of the extension modules. If the app developer needs to rely on a different version of an Express ext

Adding 2 nodes to an existing 3-node ZooKeeper ensemble without losing the Quorum

Since many deployments may start out with 3 nodes and so little is known about how to grow a cluster from 3 memebrs to 5 members without losing the existing Quorum, here is an example of how this might be achieved.

In this example, all 5 nodes will be running on the same Vagrant host for the purpose of illustration, running on distinct configurations (ports and data directories) without the actual load of clients.

YMMV. Caveat usufructuarius.

Step 1: Have a healthy 3-node ensemble

Make it real

Ideas are cheap. Make a prototype, sketch a CLI session, draw a wireframe. Discuss around concrete examples, not hand-waving abstractions. Don't say you did something, provide a URL that proves it.

Ship it

Nothing is real until it's being used by a real user. This doesn't mean you make a prototype in the morning and blog about it in the evening. It means you find one person you believe your product will help and try to get them to use it.


	'''
	rate_limit.py

	Written May 7-8, 2014 by Josiah Carlson
	Released under the MIT license.

	Offers a simple interface for offering rate limiting on a per second, minute,
	hour, and day basis. Useful for offering varying rate limits depending on user
	behavior. Sliding window based limits offer per minute, hour, and day limits

	#include <unistd.h>
	#include <node.h>
	#include <string.h>
	#include <v8.h>

	using namespace v8;

	unsigned long long count = 0;

	// native blocking/compute intensive function

	// How to use it.
	//
	// This code is based on the template file that YOGI produces for unit testing
	// when a module is created. Only the main changes to it are listed.
	//
	// Add a reference to the module in the YUI configuration section so it can locate it
	// It's up to you where you put it.
	YUI({
	groups: {
	leaks: {

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048