CODEWITHSUNDEEP
chef-infra
JB.
JB.

Reputation: 42154

How do I declare a Chef file resource whose contents depend on cookbook files?

I need a file fileC deployed that's the concatenation of two other files fileA and fileB. In my current setup, all three files are in the cookbook, declared as Cookbook File resources.

But it feels redundant. I'd like to declare the bigger file as a function of the two others.

When fileC was first needed, I got it to "almost work" by luck by declaring the file resource's contents as IO.read(file1) + IO.read(file2). But that fails as soon as the recipe is deployed to a new node, since fileA and fileB aren't present at compile time.

I tried to access the underlying Ruby objects' information on where the cookbook could be deployed. But the more I looked, the less I was convinced it was possible with my level of Chef/Ruby knowledge. The resource↔provider gap seems too wide.

I'd like to avoid the cat fileA fileB >fileC type of solution, for the following reason: in the future, I'll likely need to disciminate nodes that need C from nodes that need A/B.

Any ideas on how to address the redundancy?

Upvotes: 3

Views: 3602

Answers (2)

JoshMahowald
JoshMahowald

Reputation: 443

If you used a template, I think you could get away with it. e.g.

template "/var/tmp/fileC.txt" do
   source "fileC.erb"
   variables(:included_files => ["/var/tmp/file1.txt", "/var/tmp/file2.txt"])
end

And then in your template 

<% @included_files.each { |file|  %>
<%= File.read(file) %>    
<% } %>

Upvotes: 5

Tim Potter
Tim Potter

Reputation: 2457

Here's my solution. Unfortunately it does involve a "cat" command, but the list of files is abstracted out into a list which can be set or modified using attributes:

files = ["foo", "bar"]    # Or retrieve from an attribute

execute "cat files" do
  command "cat #{files.map {|f| "/var/tmp/#{f} "}} > /var/tmp/foobar"
  action :nothing
end

files.each do |f|
  cookbook_file "/var/tmp/#{f}" do
    source f
    notifies :run, "execute[cat files]", :immediately
  end
end

I'm curious what the use case is here though. My guess is two configuration fragments that need to be mashed together for a service that doesn't support a conf.d arrangement.

Upvotes: 1

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