What is cookbook template (.erb)

A cookbook template is an Embedded Ruby (ERB) template that is used to dynamically generate static text files. Templates may contain Ruby expressions and statements, and are a great way to manage configuration files.

Use the template resource to add cookbook templates to recipes; place the corresponding Embedded Ruby (ERB) template file in a cookbook’s /templates directory. template resource would not work with chef-apply but can be used with chef-solo.

Use the template resource to manage the contents of a file using an Embedded Ruby (ERB) template by transferring files from a sub-directory of COOKBOOK_NAME/templates/ to a specified path located on a host that is running Chef Infra Client.

ERB Specification

Chef uses Erubis as its template language. It allows embedding pure Ruby code inside special symbols in the templates.

	Example
	# Content of index.html.erb
	# index.html.erb must be located at cookbook/templates/index.html.erb
	<h1> This is our chef ohai attributes <%=node['platform'] %></h1>
	<h1> This is our Recipe attributes <%=node['devopsschool']['message'] %></h1>
	<% node['learn_chef_httpd']['default'].each do |key, value| -%>
	<% unless value.empty? -%>
	<%= key %>=<%= value %>
	<% end %>
	<% end %>
	<%- 4.times do %>
	<%= @hi %>, <%= @world %> from <%= @from %>!
	<%- end %>
	# Content of attributes/default.rb
	default['elasticsearch']['default']['ES_USER'] = ''
	default['elasticsearch']['default']['ES_GROUP'] = ''
	default['elasticsearch']['default']['ES_HEAP_SIZE'] = ''
	default['elasticsearch']['default']['MAX_OPEN_FILES'] = ''
	default['elasticsearch']['default']['MAX_LOCKED_MEMORY'] = 'unlimited'
	default['elasticsearch']['default']['MAX_MAP_COUNT'] = ''
	default['elasticsearch']['default']['LOG_DIR'] = '/var/log/elasticsearch'
	default['elasticsearch']['default']['DATA_DIR'] = '/var/lib/elasticsearch'
	default['elasticsearch']['default']['WORK_DIR'] = '/tmp/elasticsearch'
	default['elasticsearch']['default']['CONF_DIR'] = '/etc/elasticsearch'
	default['elasticsearch']['default']['CONF_FILE'] = '/etc/elasticsearch/elasticsearch.yml'
	default['elasticsearch']['default']['RESTART_ON_UPGRADE'] = ''
	# Content of default.rb
	template "/var/www/html/index.html" do
	source "index.html.erb"
	owner 'root'
	group 'root'
	mode '0755'
	variables(
	hi: 'Tesing',
	world: 'Welt',
	from: node['fqdn']
	)
	end
	template '/etc/sudoers' do
	source 'sudoers.erb'
	mode '0440'
	owner 'root'
	group 'root'
	variables(sudoers_groups: node['authorization']['sudo']['groups'],
	sudoers_users: node['authorization']['sudo']['users'])
	end
	Content of templates/default/sudoers.erb
	------------------------------------------
	#
	# /etc/sudoers
	#
	# Generated by Chef for <%= node['fqdn'] %>
	#
	Defaults !lecture,tty_tickets,!fqdn
	# User privilege specification
	root ALL=(ALL) ALL
	<% @sudoers_users.each do |user| -%>
	<%= user %> ALL=(ALL) <%= "NOPASSWD:" if @passwordless %>ALL
	<% end -%>
	# Members of the sysadmin group may gain root privileges
	%sysadmin ALL=(ALL) <%= "NOPASSWD:" if @passwordless %>ALL
	<% @sudoers_groups.each do |group| -%>
	# Members of the group '<%= group %>' may gain root privileges
	<%= group %> ALL=(ALL) <%= "NOPASSWD:" if @passwordless %>ALL
	<% end -%>
	Content of attributes/default.rb
	# --------------------------------------
	default['authorization']['sudo']['groups'] = %w(sysadmin wheel admin)
	default['authorization']['sudo']['users'] = %w(jerry greg)

view raw chef-template.rb hosted with by GitHub

Reference

• https://docs.chef.io/templates/
• https://github.com/scmgalaxy/chef-repo
• https://docs.chef.io/resources/template/
• https://docs.aws.amazon.com/opsworks/latest/userguide/cookbooks-101-basics-attributes.html

Rajesh Kumar

I’m a DevOps/SRE/DevSecOps/Cloud Expert passionate about sharing knowledge and experiences. I am working at Cotocus. I blog tech insights at DevOps School, travel stories at Holiday Landmark, stock market tips at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at I reviewed , and SEO strategies at Wizbrand. 

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