[chef] Re: Re: JSON Role files, attributes, and variable interpolation

Chronological Thread 
  • From: Mike < >
  • To:
  • Subject: [chef] Re: Re: JSON Role files, attributes, and variable interpolation
  • Date: Tue, 30 Dec 2014 20:15:41 +0000

To further clarify:

Role data can be dynamic, as long as the dynamic part is pure Ruby, and does not rely on any external data, such as node attributes.

Roles in Ruby will be converted to JSON data structures, so you may use Ruby in a role before uploading it, but once uploaded, you will no longer be able to download the precompiled Ruby form.

For instance:
  'package_list' => %w(foo bar)

JSON, from Chef Server:
"default_attributes": {
  "package_list": [


On Tue Dec 30 2014 at 2:07:49 PM Noah Kantrowitz < "> > wrote:
No, nor would this work in the ruby format. Role data must be purely static. You can do things like this in cookbooks though.


On December 30, 2014 at 10:41:15 AM PST, Mark Selby < " target="_blank"> > wrote:
I use JSON based role files and for better or worse use them often  for attribute definition.

I have recently tried to perform variable interpolation like this

    "default_attributes": {
        "foo": {
            "server": "extra.#{node['fqdn']}"
I was not surprised that this DID NOT work and that I got 'extra.#{node['fqdn']}' rather than an interpolated string.

Is there any way to interpolate in JSON role files?


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