jlyonsmith

server {
  listen 80;
  server_name yournamehere.com;
  return 301 https://$host$request_uri;
}

server {
  listen 443 ssl;
  server_name yournamehere.com;

jlyonsmith

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?

jlyonsmith

download

wget https://docs.broadcom.com/docs-and-downloads/raid-controllers/raid-controllers-common-files/8-07-14_MegaCLI.zip

unzip

unzip 8-07-14_MegaCLI.zip

jlyonsmith

Common symbols

Modifiers

When a key combination is displayed, the modifiers are written in the order presented here. For example, Control + Option + Shift + Command + Q would be written as ⌃⌥⇧⌘Q.

Sym	Key	Alt
⌃	Control
⌥	Option

jlyonsmith

An Ansible summary

Jon Warbrick, July 2014, V3.2 (for Ansible 1.7)

Configuration file

intro_configuration.html

First one found from of

jlyonsmith

# Add this snippet to the top of your playbook. 
# It will install python2 if missing (but checks first so no expensive repeated apt updates)
# gwillem@gmail.com

- hosts: all
  gather_facts: False
  
  tasks:
  - name: install python 2
    raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal)

jlyonsmith

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

jlyonsmith

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

jlyonsmith

# Example nginx + git HTTP Smart mode (git-http-backend) + HTTP Authentication + HTTPS redirect
# jeroen@massar.ch - http://jeroen.massar.ch
 
server {
  listen  192.0.1.1:80;
  listen  [2001:db8::1]:80;
 
  # Redirect all non-HTTPS traffic to the HTTPS variant
  return 301 https://$host$request_uri;
}

jlyonsmith

navigator.serviceWorker.getRegistrations().then(function (registrations) {
  if (!registrations.length) {
    console.log('No serviceWorker registrations found.')
    return
  }
  for(let registration of registrations) {
    registration.unregister().then(function (boolean) {
      console.log(
        (boolean ? 'Successfully unregistered' : 'Failed to unregister'), 'ServiceWorkerRegistration\n' +
        (registration.installing ? '  .installing.scriptURL = ' + registration.installing.scriptURL + '\n' : '') +