Chef Reusability!Config Management Camp!

Ghent, Belgium!February 2015

Sean OMeara!sean@chef.io!

@someara

whoami

Part 1

Things that are true

New Chef users expect community cookbooks to just work

Especially the Chef maintained cookbooks

This is not the current state of things

This leads to sadness

We must repair it

People copy patterns

The status quo cannot be allowed to continue

Common pain points

https://www.flickr.com/photos/kwl/4595324641

Platform and version support

Weak scoping

No standard interface

Compilation phase work

Needing chef-rewind

Attributes and precedence

Pattern proliferation

The path out of the darkness

https://www.flickr.com/photos/71267357@N06/15864687537

Change how cookbooks are written

systems

beliefs! behaviors

Standardize interfaces

Eliminate the pain points

Focus on resources

Make it super easy!to write resources

Ship resources for ALL THE THINGS

Copy better patterns

Make it fucking delightful

Part 2

Simple design patterns

https://www.flickr.com/photos/pollock/4172865252

You just separated data from code

You also just built an interface

Complex design patterns

https://www.flickr.com/photos/alanosaur/6417040565

This is where things get weird

amazon debian-6 debian-7 ubuntu-10.04 ubuntu-12.04 ubuntu-14.04 centos-5 centos-6 centos-7 freebsd-9 freebsd-10

Debconf!Docker!LaunchD!Runit!SMF!Simple!SystemD!Sysvinit!Upstart!Windows Services

There is a large amount of variation between software versions

There is an insane amount variation across platforms

These differences need to be handled somewhere

Early techniques did everything in the recipe

data

resource pattern

Later techniques focused on isolation

Resource pattern isolation

private recipes by convention

Resource data isolation

We now have decision logic in our interface

Default values often need to be computed

Doing this in the interface leads to sorrow

We need a better way

Consumption Patterns

https://www.flickr.com/photos/ektogamat/2578779839

Why resources are best

https://www.flickr.com/photos/cross_stitch_ninja/4932950637

node attributes roles environments databags are nice to haves

They drive data about resources

Resources are fundamental

Resources are strongly scoped

Resources have a standardized interface

Resources have types, names, and parameters

Type

Name

Parameters

Resources have identities

Resource can see each other

Promise to talk

Promise to listen

Resource behave the same across platforms

Resource can have multiple providers

Writing simple resources

yum

</switches github>

Writing complex resources

mysql httpd

</switches github>

fin