IT Automation with Chef

IT Automation with Chef
Anuchit Chalothorn
anuchit@redlinesoft.net

Chef Server
*hosted*
Node
*chef-client*
Workstation
*chef*
Git

Tools
● Chef client tools for admin workstation
● Chef server
● Node with bootstrap

Chef client
Install from http://www.getchef.com/chef/install/ choose
match with your operating system and arch.

Chef client
* for Linux and Mac user can use shell script installer from curl :)

Chef server
You can use on premises chef server or use hosted chef.
choose your version at http://www.getchef.com/chef/choose-
your-version/

Starter kit
Download Starter Kit on Administration page, then extract to
your home directory.

Git repository
Chef need repository for your cookbook. Change to your chef-
repo and using git to init your repository.
git init
git add .
git commit -m “add starter kit”
* Ref : Customized Git Configuration

Try knife
Change to your Chef repo directory and use knife command line
eg: knife client list
knife client list

Node bootstrap
To add node to Chef server, use knife bootstrap to your node.
knife bootstrap fqdn/ip --sudo -x username -P passwd
-N "nodename"
knife bootstrap 192.168.2.138 --sudo -x username -P passwd -N
"nodename"

Cookbook
Now write your first cookbook call apache, use knife to create
new cookbook.
knife cookbook create apache

Cookbook : Apache
Edit cookbooks/apache/recipes/default.rb to create
your recipe, with following structure
# install apache
...
# start the apache service make sure the service starts
...
# write our home page
...

Cookbook : Apache
# install apache
package "apache2" do
action :install
end
# start the apache service make sure the service starts
service "apache2" do
action [ :enable, :start]
end
cookbook_file "/var/www/index.html" do
source "index.html"
mode "0644"
end

Cookbook : Apache
At the last part in cookbook_file you must have index.html in
cookbooks/apache/files/default/index.html write
your own content.
<html>
<title>Hello World from Chef</title>
<body>
<h1>Hello World from Chef</h1>
</body>
</html>

Cookbook upload
Each part call resources, which are step to install apache,
enable service and create default html file. Now you are ready to
publish your cookbook.
knife cookbook upload apache

Cookbook
Ubuntu need you to update APT cache before install any
package the you shuld create apt cookbook to update APT
cache first
knife cookbook create apt

Cookbook : apt
Use the execute command to update APT cache
execute "apt-get update" do
command "apt-get update"
end

Cookbook upload
Now you are ready to publish your apt cookbook.
knife cookbook upload apt

Run list
After upload cookbook to Chef server, you must create a run list
for the node to apply recipes.

Chef Client
Now back to your node, run command sudo chef-client to
apply run list.
sudo chef-client
* Run remote by knife: knife ssh ‘name:*’ ‘sudo chef-client’ -x username -P password

Check the result
Open your browser and browse to your node with an ip address
or fqdn.

Check the report
Goto Chef server to check your report; success, failure, aborted.

Make more dynamic
Your first recipe support only Ubuntu node, then make support
another distributions you may add following items for more
dynamically
● Attributes
● Templates
● Metadata

Attributes
Add cookbooks/apache/attributes/default.rb as a
default values for your recipes.
case node["platform_family"]
when "debian"
default["package_name"] = "apache2"
default["service_name"] = "apache2"
default["document_root"] = "/var/www"
when "rhel"
default["package_name"] = "httpd"
default["service_name"] = "httpd"
default["document_root"] = "/var/www/html"
end

Recipes
# install apache
package node["package_name"] do
action :install
end
# start the apache service
# make sure the service starts
service node["service_name"] do
action [ :enable, :start]
end
template "#{node["document_root"]}/index.html" do
source "index.html.erb"
mode "0644"
end

Templates
Add template file for your index.html in
cookbooks/apache/templates/default/index.html.
erb
<html>
<title>Hello World</title>
<body>
<h1>Hello World from <%= node["fqdn"] %>!</h1>
</body>
</html>

Metadata
Edit metadata file in cookbooks/apache/metadata.rb
name 'apache'
maintainer 'Anuchit Chalothorn'
maintainer_email 'anuchit@redlinesoft.net'
license 'All rights reserved'
description 'Installs/Configures apache'
long_description IO.read(File.join(File.dirname(__FILE__), 'README.
md'))
version '0.1.0'

Rules
Roles allow you to encapsulate run lists and attribute required
for a server to be. eg:
● Web Server
● Database Server
● etc

Rules
Create role for your web server by adding a webserver.rb in
roles directory edit with following content.
name "webserver"
description "Web Server"
run_list "recipe[apache]"
default_attributes({
"company" => "RedLineSoft"
})

Rules
Create role for your web server by adding a base-ubuntu.rb
in roles directory edit with following content.
name "base-ubuntu"
description "Base Ubuntu"
run_list "recipe[apt]"

Rules
Update your cookbook version in metadata and add new role
with following knife command
knife role create from file webserver.rb
knife role create from file base-ubuntu.rb
knife cookbook upload apache

Rules
Goto Chef server and add new roles to your node instead of
using cookbook then use chef-client to apply recipes

Community Cookbook
Chef also have a community cookbooks. You can find an
interest cookbook at http://community.opscode.
com/cookbooks

Community Cookbook
You can use community cookbook from Chef community by
using knife.
knife cookbook site download mysql 4.1.2
You'll get an archive file mysql-4.1.2.tar.gz in your chef-
repo
* Easy way use; knife cookbook site install mysql

Using Community Cookbook
Now you get the archive cookbook from community already
then extract an archive to cookbooks directory
tar zxvf mysql-4.1.2.tar.gz -C cookbooks/

Check dependency in metadata.rb, if you don’t have please
download them, for homebrew, windows is dependency for OSX
and Windows if you not use it, just comment it.
depends 'openssl', '~> 1.1'
depends 'build-essential', '~> 1.4'
#depends 'homebrew'
#depends 'windows'

Read the recipe files, mysql cookbook has mysql::client,
mysql::server and mysql::ruby so you can specify which
recipe you will use.

Download dependency cookbook for mysql
knife cookbook site download openssl 1.1.0
knife cookbook site download build-essential 1.4.4
tar zxvf openssl-1.1.0.tar.gz -C cookbooks/
tar zxvf build-essential-1.4.4.tar.gz -C cookbooks/
knife cookbook upload build-essential openssl mysql

Create new role webserver-mysql to install webserver and mysql
in this role.
name "webserver-mysql"
description "Webserver and MySQL Database Server"
run_list "recipe[apache]","recipe[mysql::client]","recipe[mysql::
server]"
knife role from file webserver-mysql.rb

Goto Chef server add role to node then apply webserver-
mysql role in node

Goto node and run chef-client to apply role.
sudo chef-client

Further Resources
● http://www.opscode.com
● http://community.opscode.com
● http://docs.opscode.com
● http://learnchef.com
● http://youtube.com/user/Opscode

IT Automation with Chef

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