Skip to content

Latest commit

 

History

History
88 lines (72 loc) · 2.41 KB

cookbook_file_specificity.md

File metadata and controls

88 lines (72 loc) · 2.41 KB

A cookbook is frequently designed to work across many platforms and is often required to distribute a specific file to a specific platform. A cookbook can be designed to support the distribution of files across platforms, while ensuring that the correct file ends up on each system.

The pattern for file specificity depends on two things: the lookup path and the source attribute. The first pattern that matches is used:

  1. /host-\$fqdn/\$source
  2. /\$platform-\$platform_version/\$source
  3. /\$platform/\$source
  4. /default/\$source
  5. /\$source

Use an array with the source attribute to define an explicit lookup path. For example:

file '/conf.py' do
  source ['#{node.chef_environment}.py', 'conf.py']
end

The following example emulates the entire file specificity pattern by defining it as an explicit path:

file '/conf.py' do
  source %W(
    host-#{node['fqdn']}/conf.py
    #{node['platform']}-#{node['platform_version']}/conf.py
    #{node['platform']}/conf.py
    default/conf.py
  )
end

A cookbook may have a /files directory structure like this:

files/
    host-foo.example.com
    ubuntu-20.04
    ubuntu-20
    ubuntu
    redhat-8.2
    redhat-7.8
    ...
    default

and a resource that looks something like the following:

cookbook_file '/usr/local/bin/apache2_module_conf_generate.pl' do
  source 'apache2_module_conf_generate.pl'
  mode '0755'
  owner 'root'
  group 'root'
end

This resource is matched in the same order as the /files directory structure. For a node that is running Ubuntu 20.04, the second item would be the matching item and the location to which the file identified in the cookbook_file resource would be distributed:

host-foo.example.com/apache2_module_conf_generate.pl
ubuntu-20.04/apache2_module_conf_generate.pl
ubuntu-20/apache2_module_conf_generate.pl
ubuntu/apache2_module_conf_generate.pl
default/apache2_module_conf_generate.pl

If the apache2_module_conf_generate.pl file was located in the cookbook directory under files/host-foo.example.com/, the specified file(s) would only be copied to the machine with the domain name foo.example.com.

Host Notation

The naming of folders within cookbook directories must literally match the host notation used for file specificity matching. For example, if a host is named foo.example.com, the folder must be named host-foo.example.com.