cooking 5 star infrastructure with chef

INtroduction to Chef

Cooking 5 Star Infrastructure

Wednesday, November 21, 12

What is Chef ?

• Chef is a infrastructure configuration management platform to create infrastructure as code

• Policy enforcement tool• Continuous integration tool• What you make it


Client Server Architecture


Chef Components

• Ohai: Data collector System info and statistics

• Chef-Server: Code Repository • Chef-client: Client software• Knife: Command line interface • Shef: Testing CLI / Development Client


Chef Structures

• Roles: is a grouping of cookbooks and recipes shared between a type of node

• Node: is a machine that has roles and attributes assigned to it

• Cookbook: a collection of recipes

• Recipe: a collection of resources

• Resource: basic unit of work, package, service, template, file, exec, etc

• Attributes: node data such as IP address, Hostname, any value you set

• Data-bag: data store of globally available JSON data


What is in a CookbookWhat goes where

• Attribute node specify data

• Definitions allow you to create new resources by stringing together existing resources.

• Files you want to deploy via a cookbook

• Template ERB Template files that pull data from the node

• Resource custom define resource for the cookbook

• Recipes default.rb and other Recipes

• Libraries allow you to include arbitrary Ruby code, either to extend Chef's language or to implement your own classes directly.


Master chefs tool of choice KNIFE

Knife It is used by administrators to interact with the Chef Server API and the local Chef repository. It provides the capability to manipulate nodes, cookbooks, roles, data-bags, environments, etc., and can also be used to provision cloud resources and to bootstrap systems.

knife sub-command [ARGUMENTS] (options)

knife data bag create BAG

knife cookbook list (options)etc


RolesA role is a way to define certain patterns and processes that exist across nodes

knife node run_list add NODE "role[ROLE NAME]"

knife node run_list add NODE "role[ROLE NAME 1],role[ROLE NAME 2],role[ROLE NAME 3]"

knife role list

knife role create foobar

{ "name": "foobar", "default_attributes": { }, "json_class": "Chef::Role", "run_list": ["recipe[apache2]", "recipe[apache2::mod_ssl]", "role[monitor]" ], "description": "", "chef_type": "role", "override_attributes": { }}


Creating cookbooksknife cookbook create MYCOOKBOOK


• Recipe names are related to cookbook structure. Putting recipe[foo::bar] in a node’s run list results in cookbooks/foo/recipes/bar.rb being downloaded from chef-server and executed.

• There is a special recipe in every cookbook called default.rb. It is executed either by specifying recipe[foo] or recipe[foo::default] explicitly.

• Default.rb is a good place to put common stuff when writing cookbooks with multiple recipes, but we’re going to keep it simple and just use default.rb for everything

Recipes in Cookbooks


RecipeSimple Example of a Recipe

yum_package "autofs" do action :installend

service "autofs" do supports :restart => true, :status => true, :reload => true action [:enable, :start]end

template "/etc/auto.master" do source "auto.master.erb" owner "root" mode "0644" notifies :restart, resources(:service => "autofs" )end

template "/etc/auto.home" do source "auto.home.erb" owner "root" mode "0644" variables({! :fqdn => node[:fqdn],! :autofs_server => node[:autofs_server],! }) #notifies :restart, resources(:service => node[:autofs][:service]) notifies :restart, resources(:service => "autofs" )end


Common Resources service "memcached" doaction :nothingsupports :status => true, :start => true, :stop => true, :restart => trueend

package "some_package" doprovider Chef::Provider::Package::Rubygemsend

yum_package "netpbm" doaction :installend

template "/tmp/config.conf" dosource "config.conf.erb"variables(:config_var => node[:configs][:config_var])end

file "/tmp/something" domode "644"end


ERB Templates<%= if node[:domain] == "dc1.company.org" node.set['autofs_server'] = '10.1.4.120'end

if node[:domain] == "dc2.company.org" node.set['autofs_server'] = '10.100.0.11'end%>

* -fstype=nfs,rw,nosuid,nodev,intr,soft <%= node[:autofs_server] %>:/home_vol_01/&


Data-bags

{ "id": "some_data_bag_item", "production" : { # Hash with all your data here }, "testing" : { # Hash with all your data here }}

These are JSON Objects stored as Key value pairs or sub objects


AttributesAre simple key value stores that can be set on different object pragmatically

Attributes may be set on the node from the following objects• cookbooks• environments (Chef 0.10.0 or above only)• roles• nodes


Working With Attributes

See the full documentation for implementation Apidefault["apache"]["dir"] = "/etc/apache2"default["apache"]["listen_ports"] = [ "80","443" ]node.default["apache"]["dir"] = "/etc/apache2"node.default["apache"]["listen_ports"] = [ "80","443" ]node.set['apache2']['proxy_to_unicorn'] = node['rails']['use_unicorn'] normal / set Attribute

Precedence

The precedence of the attributes is as follows, from low to high:

1. default attributes applied in an attributes file2. default attributes applied in an environment3. default attributes applied in a role4. default attributes applied on a node directly in a recipe5. normal or set attributes applied in an attributes file6. normal or set attributes applied on a node directly in a recipe7. override attributes applied in an attributes file8. override attributes applied in a role9. override attributes applied in an environment10.override attributes applied on a node directly in a recipe11.automatic attributes generated by Ohai

default attributes applied in an attributes file have the lowest priority and automatic attributes generated by Ohai have the highest priority.

Write your cookbooks with default attributes, but override these with role-specific or node-specific values as necessary.


http://wiki.opscode.com/display/chef/Attributes

http://wiki.opscode.com/display/chef/Attributes

http://wiki.opscode.com/display/chef/Ohai




Working OHAI

• When invoked, it collects detailed, extensible information about the machine it's running on, including Chef configuration, hostname, FQDN, networking, memory, CPU, platform, and kernel data.

• When used standalone, Ohai will print out a JSON data blob for all the known data about your system.

• When used with Chef, that JSON output is reported back via "automatic" node attributes to update the node object on the chef-server.

• Ohai plugins provide additional information about your system infrastructure - Custom Ohai Plugin to gather that other information.

Ohai detects data about your operating system. It can be used standalone, but its primary purpose is to provide node data to Chef.


Jenkins and Branching

• Roll forward methodology a rollback is a push forward in version but pervious production push locked branch.

• Multiple branches to be compiled • Post Production ( Previous stable push branch)

• Pre Production ( Staging 2 push or current push brach )

• Testing ( Smoke testing push in staging 1 )


Continues integrationWith Chef

• Automated Testing and Building Env• Smoke tests on staging 1 environments • Staging 1 one Colo 10% yum repo• Staging 2 multi Colo 50% yum repo• Production 100% yum repo


QUESTIONS ?


cooking 5 star infrastructure with chef

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