The software industry is surrounded by complexity, with new solutions to old problems appearing daily. Creators of software constantly face questions about how to best navigate changing technology tides while still building their “ships". Building these ships, or building software, requires picking challenges and making sensible technical choices to move fast without compromising stability. In this talk, GitHub’s Director of Systems Sam Lambert will explore how GitHub steers its ship—the world’s largest software host serving over 11M users—on top of stable, proven systems and services. He’ll speak specifically about how these practices can be translated to any type of software creation by focusing on: -The importance of pragmatism during building and maintaining software systems. -How a company like GitHub moves fast and breaks as little as possible by carefully choosing what problems to tackle. -Why this simple path of choosing and solving problems can prove extremely useful. The role new technologies can play in informing decisions and approaches around what problems to solve.

1. Building New on top of old:
The argument for simplicity
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Sam Lambert
Director of Systems, GitHub

2. How people build software
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Building New on Top of Old
The Argument for Simplicity

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Sam Lambert
Director of Systems
! github.com/samlambert
! twitter.com/isamlambert
! samlambert.com
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GitHub
Code hosting and collaboration
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Where do we work?

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Hubot

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Hubot

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Hubot

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Hubot

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OVER 11 MILLION USERS
29 MILLION REPOSITORIES
What is GitHub?

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Scale can be relative
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Who are the Systems Organization?
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GIT AND GIT SYSTEMS
DATABASE SYSTEMS

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The Systems Philosophy
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Above all else, GitHub is a Unix shop. We
create programs and tools that follow the
basic principles of Unix: simplicity,
modularity, composability.
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We believe that it is always easier to
add complexity than it is to remove it.
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We are excited by new tools, but we
never use them just to use them. We
experiment, but we will always prefer
what is proven over what is new.
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Simplicity
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Why?
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Is this wrong?
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The Stack
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MySQL
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Ruby
Rails
C
ElasticSearch
Javascript
Git
Shell

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Pragmatism

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What do we get?

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Sleep!

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Predictability

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Right tool for the job?

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Community knowledge

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MySQL

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Why do *we* naturally build
complex systems?

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Innovation

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The role of new technologies
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MySQL
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No approach you can’t borrow from
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Brubeck
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Brubeck’s feature is that it has no features. It is a
very simple C daemon that uses state-of-the-art
technologies such as “a while loop” and “more than
one thread”.
- Vicent Marti
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GitHub Enterprise
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Multiple repos, complex build process
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The rewrite
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LXE
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#!
/bin/bash
mkdir
-­‐p
./chroot
debootstrap
-­‐-­‐arch=amd64
precise
./chroot
chroot
./chroot
apt-­‐get
install
...
cp
-­‐r
<whatever>
./chroot/etc
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Reduction in complexity
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1986
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Iteration
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Are we strengthening our
foundations or rebuilding them?
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@EricaJoy
@EricaStanley
@eanakashima
@skamille

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Questions?