Leon Mak leonmak

Virtual Hosts on nginx (CSC309)

When hosting our web applications, we often have one public IP address (i.e., an IP address visible to the outside world) using which we want to host multiple web apps. For example, one may wants to host three different web apps respectively for example1.com, example2.com, and example1.com/images on the same machine using a single IP address.

How can we do that? Well, the good news is Internet browsers

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)

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Currently, there is an explosion of tools that aim to manage secrets for automated, cloud native infrastructure management. Daniel Somerfield did some work classifying the various approaches, but (as far as I know) no one has made a recent effort to summarize the various tools.

This is an attempt to give a quick overview of what can be found out there. The list is alphabetical. There will be tools that are missing, and some of the facts might be wrong--I welcome your corrections. For the purpose, I can be reached via @maxvt on Twitter, or just leave me a comment here.

There is a companion feature matrix of various tools. Comments are welcome in the same manner.

Some of the Redis best practices content has moved

This content from this markdown file has moved a new, happier home where it can serve more people. Please check it out : https://docs.microsoft.com/azure/azure-cache-for-redis/cache-best-practices.

NOTE: Client specific guidance listed below is still valid and should still be considered. I will update this document once all content has been moved.

	# Hello, and welcome to makefile basics.
	#
	# You will learn why `make` is so great, and why, despite its "weird" syntax,
	# it is actually a highly expressive, efficient, and powerful way to build
	# programs.
	#
	# Once you're done here, go to
	# http://www.gnu.org/software/make/manual/make.html
	# to learn SOOOO much more.

	#! /bin/bash

	# directory to save backups in, must be rwx by postgres user
	BASE_DIR="/var/backups/dokku-postgres"
	YMD=$(date "+%Y-%m-%d")
	DIR="$BASE_DIR/$YMD"

	# make dir if it doesn't exist
	mkdir -p $DIR
	cd $DIR

	node {
	echo 'Results included as an inline comment exactly how they are returned as of Jenkins 2.121, with $BUILD_NUMBER = 1'
	echo 'No quotes, pipeline command in single quotes'
	sh 'echo $BUILD_NUMBER' // 1
	echo 'Double quotes are silently dropped'
	sh 'echo "$BUILD_NUMBER"' // 1
	echo 'Even escaped with a single backslash they are dropped'
	sh 'echo \"$BUILD_NUMBER\"' // 1
	echo 'Using two backslashes, the quotes are preserved'
	sh 'echo \\"$BUILD_NUMBER\\"' // "1"

	#!/bin/bash
	#
	# pcap2wav
	# Original Author: Michael Collins <[email protected]>
	#Standard disclaimer: batteries not included, your mileage may vary...
	# Updated by Avi Marcus <[email protected]>
	#
	# Accepts arg of pcap file w/only 2 RTP streams
	# Creates a .<codec> file and a .wav file
	# For codecs other than PCMA and PCMU the script calls fs_cli and does a little recording to create the wav file(s)