Chef Workshop

Dawg Days 2016

Eric Fusciardi

Getting Started

  • Preinstalled the toolchain?

  • Tested you can run VMs?

  • Cheat sheet of commands

 

What you should be a little familiar with, and if you're not it's not that big of a deal 

Bash / SSH / Linux shell

JSON

YAML

Ruby

All the ruby you need to know

  • String interpolation
    • ' vs " semantics
  • Map accessing
  • Map creation
  • Loops
  • "Ruby equivalent of XYZ" > google.com
    • But seriously you won't use much ruby if you don't want to.
  • Scope of variables / attributes

Exercise 1 goals

  • Spin up a VM
  • Install apache
  • Look at it in your browser
  • Observe re-run behavior

 

 

 

This is mostly just getting familiar with the kitchen toolchain and how chef manages state.

If this was a shell script

yum install -y httpd

service httpd start

Basic, amirite?

Oh but that second run sucks quite a lot

yum install -y httpd

> httpd already installed

service httpd start

> starting [httpd] [FAILED]

The overarching theme

You declare Resources.
Thats it.

Resources are the first-class citizen in chef scripts, and represent a piece of desired configuration.

Insert into google > "chef resource <A THING>" and you'll probably get a relavent hit

user, group, file, directory, package, service, link, cron, envvars, git creds, disk mounts, bash script, arbitrary ruby code, whatever.

They're all resources.

Exercise 2 goals

Part 1

  • Spin up a VM
  • Make a user on it with your pubkey
  • Using file templates
  • Using cookbook files
  • Setup a ssh banner
  • SSH to the host without password prompt

Part 2

  • Use a different method of setting up the ssh banner
  • Guards

Protip:  If you're not using pageant or  ~/.ssh/id_rsa to handle your own ssh auth, you're missing out.

Every resource.
Every time.

Chef has no concept of "Oh I just updated to this new code, only do this"

 

It is a state machine, it checks state, and if the state is not as described, it applies it.

Exercise 3 goals

Part 1

  • Looping
  • Resource attributes
  • Ohai
  • Vagrant Boxes
  • Multiple VMs
    • Port forwarding
  • Multiple OSes

Part 2

  • Test cases
    • bats
    • server-spec
    • 'test' vs 'verify'

node['platform_version']

This wasn't defined.

ohai

  • Can run it from command line
  • Aggregates and exposes host-specific settings
    • IP address
    • Hostname / FQDN
    • Processors
    • Memory
    • Disk mounts
    • A whole butt-ton more

bats vs server-spec

Baaaats!  Bats in my face!

bats

  • Mostly bash syntax
  • Very new to the scene
  • Has way better support for environment vars, userlevel settings, and less boilerplate

server-spec

  • Blend of ruby and bash
  • Similar to chef overall in that aspect
  • Better verbosity in failures
  • More boilerplate needed
  • Slower to install - server-spec gems take a minute or so to import on every new VM.

Exercise 4 goals

  • Knife
  • Data bag encryption

D-Bags

You knew this was coming

knife data bag [create|edit|delete] directory_name document_name

set your EDITOR env variable.

Mac users:  export EDITOR='vi'

Windows users: set EDITOR='notepad.exe'

 

(you can use custom editors if you want, test it out.)

 

Exercise 5 goals

  • Using third party cookbooks
    • And their sometimes depressing dependency trees
  • Berkshelf dependency management
  • Composing cookbooks
  • Attribute precedence
  • Packaging a deployable

How it all works when you have a chef-server

  • Config + Auth your local knife tool to the chef-server
    • ~/chef/knife.rb
  • Upload your code to the chef-server
    • berks package / berkflow
    • encrypted data bags

How it all works when you have a chef-server

  • Make the target VM
  • Hook it to the network
  • Associate a host to the chef-server
    • knife bootstrap
  • Assign it a runlist, data bag keys, environment attributes, etc
  • ssh to host, run chef-client

What chef doesn't do

  • OS installation
  • Initial incredibly base networking requirements
    • Most notably, it needs to be able to talk to the chef server and resolve it in DNS
  • Give a damn about users manually manipulating the files you told chef to control
  • Magic
  • "Chef-ify-ing" your app

It's really just a super fancy shell script.

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