cookbook refactoring & abstracting logic to ruby(gems)

Cookbook Refactoring

A

Cookbook Refactoring

... and extracting logic into Rubygems

A

sethvargo@opscode.com

E

byz

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THIS

template '/etc/hosts' do owner 'root' group 'root' source 'etc/hosts'end

recipes/default.rb

# This file is managed by Chef for "<%= node['fqdn'] %>"# Do NOT modify this file by hand.

<%= node['ipaddress'] %> <%= node['fqdn'] %>127.0.0.1!localhost <%= node['fqdn'] %>255.255.255.255!broadcasthost::1 localhost fe80::1%lo0! localhost

templates/default/etc/hosts.erb

default['etc']['hosts'] = [] unless node['etc']['hosts']

attributes/default.rb

# This file is managed by Chef for "<%= node['fqdn'] %>"# Do NOT modify this file by hand.

<%= node['ipaddress'] %> <%= node['fqdn'] %>127.0.0.1!localhost <%= node['fqdn'] %>255.255.255.255!broadcasthost::1 localhost fe80::1%lo0! localhost

# Custom Entries<% node['etc']['hosts'].each do |h| -%><%= h['ip'] %> <%= h['host'] %><% end -%>

templates/default/etc/hosts.erb

include_attribute 'hostsfile'

default['etc']['hosts'] << { 'ip' => '1.2.3.4', 'host' => 'www.example.com'}

other_cookbook/attributes/default.rb

node.default['etc']['hosts'] << { 'ip' => '1.2.3.4', 'host' => 'www.example.com'}

other_cookbook/recipes/default.rb

default_attributes({ 'etc' => { 'hosts' => [ {'ip' => '1.2.3.4', 'host' => 'www.example.com'}, {'ip' => '4.5.6.7', 'host' => 'foo.example.com'} ] }})

roles/my_role.rb

{ "default_attributes": { "etc": { "hosts": [ {"ip": "1.2.3.4", "host": "www.example.com"}, {"ip": "4.5.6.7", "host": "foo.example.com"} ] } }}

environments/production.json

node.set['etc']['hosts'] = { ip: '7.8.9.0', host: 'bar.example.com'})

recipes/default.rb

arr = [1,2,3]

arr << 4 => [1,2,3,4]arr = 4 => 4

arr = [1,2,3]

arr << 4 => [1,2,3,4]arr = 4 => 4

Not an Array

TODO: Add infographics

# This file is managed by Chef for "www.myapp.com"# Do NOT modify this file by hand.

1.2.3.4 www.myapp.com127.0.0.1!localhost www.myapp.com255.255.255.255!broadcasthost::1 localhost fe80::1%lo0! localhost

# Custom Entries1.2.3.4 www.example.com4.5.6.7 foo.example.com7.8.9.0 bar.example.com

/etc/hosts

TODO: Add infographics

# This file is managed by Chef for "www.myapp.com"# Do NOT modify this file by hand.

1.2.3.4 www.myapp.com127.0.0.1!localhost www.myapp.com255.255.255.255!broadcasthost::1 localhost fe80::1%lo0! localhost

# Custom Entries7.8.9.0 bar.example.com

/etc/hosts

Post Mortem

<< =

<< =!=

Post Mortem

Action Items

7

Monkey patch Chef to raise an exception when redefining that

particular node attribute.

Monkey patch Chef to raise an exception when redefining that

particular node attribute.t

Create a special cookbook that uses a threshold value and raises an

exception if the size of the array doesn't "make sense".

Create a special cookbook that uses a threshold value and raises an

exception if the size of the array doesn't "make sense".t

Move all entries to a data bag

Move all entries to a data bag

u

Move all entries to a data bag66 Add tests

Data Bags

[ "1.2.3.4 example.com www.example.com", "4.5.6.7 foo.example.com", "7.8.9.0 bar.example.com"]

data_bags/etc_hosts.json

hosts = data_bag('etc_hosts')

template '/etc/hosts' do owner 'root' group 'root' source 'etc/hosts' variables( hosts: hosts )end

recipes/default.rb

# This file is managed by Chef for "<%= node['fqdn'] %>"# Do NOT modify this file by hand.

<%= node['ipaddress'] %> <%= node['fqdn'] %>127.0.0.1!localhost <%= node['fqdn'] %>255.255.255.255!broadcasthost::1 localhost fe80::1%lo0! localhost

# Custom Entries<%= @hosts.join("\n") %>

templates/default/etc/hosts.erb

Move all entries to a data bag56 Add tests

require 'chefspec'

spec/default_spec.rb

require 'chefspec'

describe 'hostsfile::default' do

end

spec/default_spec.rb

require 'chefspec'

describe 'hostsfile::default' do let(:hosts) { ['1.2.3.4 example.com', '4.5.6.7 bar.com'] }

before do Chef::Recipe.any_instance.stub(:data_bag).with('etc_hosts').and_return(hosts) end

end

spec/default_spec.rb

require 'chefspec'

describe 'hostsfile::default' do let(:hosts) { ['1.2.3.4 example.com', '4.5.6.7 bar.com'] }

before do Chef::Recipe.any_instance.stub(:data_bag).with('etc_hosts').and_return(hosts) end

let(:runner) { ChefSpec::ChefRunner.new.converge('hostsfile::default') }

end

spec/default_spec.rb

require 'chefspec'

describe 'hostsfile::default' do let(:hosts) { ['1.2.3.4 example.com', '4.5.6.7 bar.com'] }

before do Chef::Recipe.any_instance.stub(:data_bag).with('etc_hosts').and_return(hosts) end

let(:runner) { ChefSpec::ChefRunner.new.converge('hostsfile::default') }

it 'loads the data bag' do Chef::Recipe.any_instance.should_receive(:data_bag).with('etc_hosts') end

end

spec/default_spec.rb

require 'chefspec'

describe 'hostsfile::default' do let(:hosts) { ['1.2.3.4 example.com', '4.5.6.7 bar.com'] }

before do Chef::Recipe.any_instance.stub(:data_bag).with('etc_hosts').and_return(hosts) end

let(:runner) { ChefSpec::ChefRunner.new.converge('hostsfile::default') }

it 'loads the data bag' do Chef::Recipe.any_instance.should_receive(:data_bag).with('etc_hosts') end

it 'creates the /etc/hosts template' do expect(runner).to create_template('/etc/hosts').with_content(hosts.join("\n")) endend

spec/default_spec.rb

$ rspec cookbooks/hostsfile

Running all specs

$ rspec cookbooks/hostsfile

Running all specs

**

Finished in 0.0003 seconds2 examples, 0 failures

$ rspec cookbooks/hostsfile

Running all specs

**

Finished in 0.0003 seconds2 examples, 0 failures

Really Fucking Fast™

#winning

10,000 tests

28 seconds

#winning

⏳⏳

hosts = data_bag('etc_hosts')

hosts << search(:node, 'role:mongo_master').first.tap do |n| "#{n['ip_address']} #{n['fqdn']}"end

template '/etc/hosts' do owner 'root' group 'root' source 'etc/hosts' variables( hosts: hosts )end

recipes/default.rb

hosts = data_bag('etc_hosts')

hosts << search(:node, 'role:mongo_master').first.tap do |n| "#{n['ip_address']} #{n['fqdn']}"end

hosts << search(:node, 'role:mysql_master').first.tap do |n| "#{n['ip_address']} #{n['fqdn']}"end

hosts << search(:node, 'role:redis_master').first.tap do |n| "#{n['ip_address']} #{n['fqdn']}"end

template '/etc/hosts' do owner 'root' group 'root' source 'etc/hosts' variables( hosts: hosts )end

recipes/default.rb

LWRPs

# List of all actions supported by the provideractions :create, :create_if_missing, :update, :remove

# Make create the default actiondefault_action :create

# Required attributesattribute :ip_address, kind_of: String, name_attribute: true, required: trueattribute :hostname, kind_of: String

# Optional attributesattribute :aliases, kind_of: Arrayattribute :comment, kind_of: String

resources/entry.rb

action :create do ::Chef::Util::FileEdit.search_file_delete_line(entry) ::Chef::Util::FileEdit.insert_line_after_match(/\n/, entry)end

protected

def entry [new_resource.ip_address, new_resource.hostname, new_resource.aliases.join(' ')].compact.join(' ').squeeze(' ') end

providers/entry.rb

hostsfile_entry '1.2.3.4' do hostname 'example.com'end

providers/entry.rb

Chef::Util::FileEdit is slow

Re-writing the file on each run

Provider kept growning

Untested

RefactorA

Move to pure Ruby classes

Ditch Chef::Util::FileEdit and manage the entire file

Only implement Ruby classes in the Provider (logic-less Provider)

Test the Ruby code

Test that the Provider implements the proper Ruby classes

TODO: Add infographics

class Entry attr_accessor :ip_address, :hostname, :aliases, :comment

def initialize(options = {}) if options[:ip_address].nil? || options[:hostname].nil? raise ':ip_address and :hostname are both required options' end

@ip_address = options[:ip_address] @hostname = options[:hostname] @aliases = [options[:aliases]].flatten @comment = options[:comment] end

# ...end

libraries/entry.rb

TODO: Add infographics

class Manipulator def initialize contents = ::File.readlines(hostsfile_path) @entries = contents.collect do |line| Entry.parse(line) unless line.strip.nil? || line.strip.empty? end.compact end

def add(options = {}) @entries << Entry.new( ip_address: options[:ip_address], hostname: options[:hostname], aliases: options[:aliases], comment: options[:comment] ) endend

libraries/manipulator.rb

# Creates a new hosts file entry. If an entry already exists, it# will be overwritten by this one.action :create do hostsfile.add( ip_address: new_resource.ip_address, hostname: new_resource.hostname, aliases: new_resource.aliases, comment: new_resource.comment )

new_resource.updated_by_last_action(true) if hostsfile.saveend

providers/entry.rb

RSpec

TODO: Add infographics

describe Entry do describe '.initialize' do subject { Entry.new(ip_address: '2.3.4.5', hostname: 'www.example.com', aliases: ['foo', 'bar'], comment: 'This is a comment!', priority: 100) }

it 'raises an exception if :ip_address is missing' do expect { Entry.new(hostname: 'www.example.com') }.to raise_error(ArgumentError) end

it 'sets the ip_address' do expect(subject.ip_address).to eq('2.3.4.5') endend

spec/entry_spec.rb

Chef Spec

Chef Spec

TODO: Add infographics

describe 'hostsfile lwrp' do let(:manipulator) { double('manipulator') } before do Manipulator.stub(:new).and_return(manipulator) Manipulator.should_receive(:new).with(kind_of(Chef::Node)) .and_return(manipulator) manipulator.should_receive(:save!) end

let(:chef_run) { ChefSpec::ChefRunner.new( cookbook_path: $cookbook_paths, step_into: ['hostsfile_entry'] ) }

spec/default_spec.rb

TODO: Add infographics

context 'actions' do describe ':create' do it 'adds the entry' do manipulator.should_receive(:add).with({ ip_address: '2.3.4.5', hostname: 'www.example.com', aliases: nil, comment: nil, priority: nil })

chef_run.converge('fake::create') end end endend

Open It

Gem It

$ bundle gem hostsfile

$ bundle gem hostsfile create hostsfile/Gemfile create hostsfile/Rakefile create hostsfile/LICENSE.txt create hostsfile/README.md create hostsfile/.gitignore create hostsfile/hostsfile.gemspec create hostsfile/lib/hostsfile.rb create hostsfile/lib/hostsfile/version.rbInitializating git repo in ~Development/hostsfile

entry.rb

manipulator.rb

99

9

9?

chef_gem 'hostsfile'

recipes/default.rb

require 'hostsfile'

providers/entry.rb

In another cookbook...

# ...

depends 'hostsfile'

other_cookbook/metadata.rb

{ "run_list": [ "recipe[hostsfile]" ]}

www.myapp.com (Chef Node)

ThankYou

z