Using a variable inside a Chef recipe

问题:

I'm using chef-cookbook-hostname cookbook to setup node's hostname. I don't want my hostname to be hard coded in the attribute file (default['set_fqdn']).

Instead the hostname will be read from a VM definition XML file. I come up with the following default recipe but apparently the variable fqdn is not given value. Is there any idea why this happens or any better to achieve my task?

ruby_block "Find-VM-Hostname" do
   block do
     require 'rexml/document'
     require 'net/http'
     url = 'http://chef-workstation/services.xml'
     file = Net::HTTP.get_response(URI.parse(url)).body
     doc = REXML::Document.new(file)
     REXML::XPath.each(doc, "service_parameters/parameter") do |element|
     if element.attributes["name"].include?"Hostname"
        fqdn = element.attributes["value"]  #this statement does not give value to fqdn
     end
     end
    end
    action :nothing
end
if fqdn
  fqdn = fqdn.sub('*', node.name)
  fqdn =~ /^([^.]+)/
  hostname = Regexp.last_match[1]

  case node['platform']
   when 'freebsd'
    directory '/etc/rc.conf.d' do
      mode '0755'
    end

    file '/etc/rc.conf.d/hostname' do
      content "hostname=#{fqdn}\n"
      mode '0644'
      notifies :reload, 'ohai[reload]'
     end
   else
    file '/etc/hostname' do
       content "#{hostname}\n"
       mode '0644'
       notifies :reload, 'ohai[reload]', :immediately
    end
   end

回答1:

The source of the problem here is that you are setting the variable fqdn inside the scope of a ruby_block and are attempting to make reference to that variable at the compilation phase. The ruby_block resources allows the ability to run ruby code during the convergence phase.

Given that you appear to be using the fqdn to setup the resource set, it looks as though you can remove the ruby block from around the ruby code. e.g.

fqdn = // logic to get fqdn

file '/tmp/file' do
  content "fqdn=#{fqdn}"
end

回答2:

I found this in the Chef docs. I ran into a similar issue. I am going to try the node.run_state. This information is found at the bottom of this page https://docs.chef.io/recipes.html

Use node.run_state to stash transient data during a chef-client run. This data may be passed between resources, and then evaluated during the execution phase. run_state is an empty Hash that is always discarded at the end of the chef-client run.

For example, the following recipe will install the Apache web server, randomly choose PHP or Perl as the scripting language, and then install that scripting language:

package "httpd" do
  action :install
end

ruby_block "randomly_choose_language" do
  block do
    if Random.rand > 0.5
      node.run_state['scripting_language'] = 'php'
    else
      node.run_state['scripting_language'] = 'perl'
    end
  end
end

package "scripting_language" do
  package_name lazy { node.run_state['scripting_language'] }
  action :install
end

回答3:

Please follow this link http://lists.opscode.com/sympa/arc/chef/2015-03/msg00266.html you can use node.run_state[:variables] for parsing one variable to another recipe

Here is my code :: file.rb

node.run_state[:script_1] = "foo" include_recipe 'provision::copy'

and in other copy.rb file put following code ::

copy.rb

filename = node.run_state[:script_1] puts "Name is #{filename}"

回答4:

I used node.run_state['variable'] for the same purpose and was successfully able to do it. Please find basic sample code below.

ruby_block "resource_name" do
   block do
     node.run_state['port_value'] = 1432
   end
end

ruby_block "resource_name2" do
   block do
      num = node.run_state['variable']
   end
end

I hope it will help.