vasanthk

System Design Cheatsheet

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

Basic Steps

1. 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?

kwilczynski

vagrant@ubuntu1404:~$ sudo salt-call --local --file-root=. --pillar-root=. state.sls test
[INFO    ] Loading fresh modules for state activity
[INFO    ] Fetching file from saltenv 'base', ** skipped ** latest already in cache 'salt://test.sls'
[INFO    ] Running state [echo 'Hello Dave, would you like to play chess?'] at time 15:05:30.278219
[INFO    ] Executing state cmd.run for echo 'Hello Dave, would you like to play chess?'
[INFO    ] Executing command "echo 'Hello Dave, would you like to play chess?'" in directory '/home/vagrant'
[INFO    ] {'pid': 2901, 'retcode': 0, 'stderr': '', 'stdout': 'Hello Dave, would you like to play chess?'}
[INFO    ] Completed state [echo 'Hello Dave, would you like to play chess?'] at time 15:05:30.282402
local:
----------

lttlrck

git branch -m old_branch new_branch         # Rename branch locally    
git push origin :old_branch                 # Delete the old branch    
git push --set-upstream origin new_branch   # Push the new branch, set local branch to track the new remote

lelandbatey

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

willurd

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

UtahDave

# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT

phobos182

input {
  syslog {
    type => "haproxy-access"
    port => 514
  }
}

filter {
  grok { 
    type => "haproxy-access"

trey

Creating a Happy Git Environment on OS X

Step 1: Install Git

brew install git bash-completion

Configure things:

git config --global user.name "Your Name"

git config --global user.email "you@example.com"

dlutzy

# -*- mode: ruby -*-
# vi: set ft=ruby : 
# David Lutz's Multi VM Vagrantfile
# inspired from Mark Barger's https://gist.github.com/2404910

boxes = [
  { :name => :web,    :role => 'web_dev',     :ip => '192.168.33.1', :ssh_port => 2201, :http_fwd => 9980, :cpus =>4, :shares => true },
  { :name => :data,        :role => 'data_dev',         :ip => '192.168.33.2', :ssh_port => 2202, :mysql_fwd => 9936, :cpus =>4 },
  { :name => :railsapp,    :role => 'railsapp_dev',     :ip => '192.168.33.3', :ssh_port => 2203, :http_fwd => 9990, :cpus =>1}
]

handloomweaver

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Simple async crawler/callback queue based on gevent."""

import traceback
import logging
import httplib2

import gevent