chef 11: any way to turn attributes into a ruby hash? - ruby

Question

I'm generating a config for my service in chef attributes. However, at some point, I need to turn the attribute mash into a simple ruby hash. This used to work fine in Chef 10:
node.myapp.config.to_hash
However, starting with Chef 11, this does not work. Only the top-level of the attribute is converted to a hash, with then nested values remaining immutable mash objects. Modifying them leads to errors like this:
Chef::Exceptions::ImmutableAttributeModification
------------------------------------------------ Node attributes are read-only when you do not specify which precedence level to set. To
set an attribute use code like `node.default["key"] = "value"'
I've tried a bunch of ways to get around this issue which do not work:
node.myapp.config.dup.to_hash
JSON.parse(node.myapp.config.to_json)
The json parsing hack, which seems like it should work great, results in:
JSON::ParserError
unexpected token at '"#<Chef::Node::Attribute:0x000000020eee88>"'
Is there any actual reliable way, short of including a nested parsing function in each cookbook, to convert attributes to a simple, ordinary, good old ruby hash?

Answer 1

after a resounding lack of answers both here and on the opscode chef mailing list, i ended up using the following hack:
class Chef
class Node
class ImmutableMash
def to_hash
h = {}
self.each do |k,v|
if v.respond_to?('to_hash')
h[k] = v.to_hash
else
h[k] = v
end
end
return h
end
end
end
end
i put this into the libraries dir in my cookbook; now i can use attribute.to_hash in both chef 10 (which already worked properly and which is unaffected by this monkey-patch) and chef 11. i've also reported this as a bug to opscode:
if you don't want to have to monkey-patch your chef, speak up on this issue:
http://tickets.opscode.com/browse/CHEF-3857
Update: monkey-patch ticket was marked closed by these PRs

Answer 2

I hope I am not too late to the party but merging the node object with an empty hash did it for me:
chef (12.6.0)> {}.merge(node).class
=> Hash

Answer 3

I had the same problem and after much hacking around came up with this:
json_string = node[:attr_tree].inspect.gsub(/\=\>/,':')
my_hash = JSON.parse(json_string, {:symbolize_names => true})
inspect does the deep parsing that is missing from the other methods proposed and I end up with a hash that I can modify and pass around as needed.

Answer 4

This has been fixed for a long time now:
[1] pry(main)> require 'chef/node'
=> true
[2] pry(main)> node = Chef::Node.new
[....]
[3] pry(main)> node.default["fizz"]["buzz"] = { "foo" => [ { "bar" => "baz" } ] }
=> {"foo"=>[{"bar"=>"baz"}]}
[4] pry(main)> buzz = node["fizz"]["buzz"].to_hash
=> {"foo"=>[{"bar"=>"baz"}]}
[5] pry(main)> buzz.class
=> Hash
[6] pry(main)> buzz["foo"].class
=> Array
[7] pry(main)> buzz["foo"][0].class
=> Hash
[8] pry(main)>
Probably fixed sometime in or around Chef 12.x or Chef 13.x, it is certainly no longer an issue in Chef 15.x/16.x/17.x

Answer 5

The above answer is a little unnecessary. You can just do this:
json = node[:whatever][:whatever].to_hash.to_json
JSON.parse(json)