Soo Philip Jason Kim philipjkim

Nginx FastCGI response buffer sizes

By default when Nginx starts receiving a response from a FastCGI backend (such as PHP-FPM) it will buffer the response in memory before delivering it to the client. Any response larger than the set buffer size is saved to a temporary file on disk.

This process is outlined at the Nginx ngx_http_fastcgi_module page manual page.

Introduction
Determine actual FastCGI response sizes
Setting the buffer size
Verifying results

Clojure Destructuring Tutorial and Cheat Sheet

(Related blog post)

Simply put, destructuring in Clojure is a way extract values from a datastructure and bind them to symbols, without having to explicitly traverse the datstructure. It allows for elegant and concise Clojure code.

Vectors and Sequences

Install tcpkill
yum -y install dsniff --enablerepo=epel

View connections
netstat -tnpa | grep ESTABLISHED.*sshd.

Block with ip tables
iptables -A INPUT -s IP-ADDRESS -j DROP

Kill connection

Delay queuing of messages in RabbitMQ/AMQP

Since RabbitMQ (and AMQP) have no specialized functionality for delay adding a message to the queue a dead-letter exchange can be used instead. This works by having two separate exchanges, one "worker exchange" and one "delay exchange", and one queue for each exchange. For each exchange and queue pair a binding has to be setup that specifies the same routing key for both exchanges.

The consumer

The consumer listens to the worker queue and any delayed message is added to the delay queue with the specified routing key and a expiration time. Instead of per-message expiration the delay queue can also specify a x-message-ttl that applies to all messages going in to it. When the message expires it will be reaped by RabbitMQ and put into the specified dead-letter exchange, the worker exchange in this case, and the routing key will direct it to the worker queue for consumption.

Delayed retry

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

	httpClient.DefaultRequestHeaders.Authorization =
	new AuthenticationHeaderValue(
	"Basic",
	Convert.ToBase64String(
	System.Text.ASCIIEncoding.ASCII.GetBytes(
	string.Format("{0}:{1}", username, password))));

	package main

	import (
	"fmt"
	"log"
	"net/http"
	"os"
	)

	func main() {

	import { MongoClient } from 'mongodb';
	import promisify from 'es6-promisify';

	let _connection;

	const connect = () => {
	if (!process.env.MONGO_CONNECTION_STRING) {
	throw new Error(`Environment variable MONGO_CONNECTION_STRING must be set to use API.`);
	}

	var OFF = 0, WARN = 1, ERROR = 2;

	module.exports = exports = {
	"env": {
	"es6": true
	},

	"ecmaFeatures": {
	// env=es6 doesn't include modules, which we are using
	"modules": true

	// Enable component-scanning and auto-configuration with @SpringBootApplication Annotation
	// It combines @Configuration + @ComponentScan + @EnableAutoConfiguration
	@SpringBootApplication
	public class FooApplication {
	public static void main(String[] args) {
	// Bootstrap the application
	SpringApplication.run(FooApplication.class, args);
	}
	}