In this post I want to discuss briefly an approach to setting up a shared Knife configuration file for teams using the same Chef Repository, while supporting customized configuration.


Most infrastructures managed by Chef have multiple people working on them. Recently, several people in the Ruby community started working together on migrating RubyGems to Amazon EC2.

The repository has a shared .chef/knife.rb which sets some local paths where cookbooks and roles are located. In addition to this, I wanted to test building the infrastructure using a Chef Server and my own EC2 account.

The Approach

At Opscode, we believe in leveraging internal DSLs. The .chef/knife.rb (and Chef’s client.rb or solo.rb, etc) is no exception. While you can have a fairly simple configuration like this:

node_name        "jtimberman"
client_key       "/home/jtimberman/.chef/jtimberman.pem"
chef_server_url  ""
cookbook_path    "cookbooks"

You can also have something like this:

log_level     :info
log_location  STDOUT
node_name     ENV["NODE_NAME"] || "solo"
client_key    File.expand_path("../solo.pem", __FILE__)
cache_type    "BasicFile"
cache_options(path: File.expand_path("../checksums", __FILE__))
cookbook_path [ File.expand_path("../../chef/cookbooks", __FILE__) ]
if ::File.exist?(File.expand_path("../knife.local.rb", __FILE__))
  Chef::Config.from_file(File.expand_path("../knife.local.rb", __FILE__))

This is the knife.rb included in the RubyGems-AWS repo.

The main part of interest here is the last three lines.

if ::File.exist?(File.expand_path("../knife.local.rb", __FILE__))
  Chef::Config.from_file(File.expand_path("../knife.local.rb", __FILE__))

This says “if a file knife.local.rb exists, then load its configuration. The Chef::Config class is what Chef uses for configuration files, and the #from_file method will load the specified file.

In this case, the content of my knife.local.rb is:

node_name                "jtimberman"
client_key               "/Users/jtimberman/.chef/jtimberman.pem"
validation_client_name   "ORGNAME-validator"
validation_key           "/Users/jtimberman/.chef/ORGNAME-validator.pem"
chef_server_url          ""
cookbook_path [
  File.expand_path("../../chef/cookbooks", __FILE__),
  File.expand_path("../../chef/site-cookbooks", __FILE__)
knife[:aws_access_key_id]      = "Some access key I like"
knife[:aws_secret_access_key]  = "The matching secret access key"

Here I’m setting my Opscode Hosted Chef credentials and server. I also set the cookbook_path to include the site-cookbooks directory (this should probably go in the regular knife.rb). Finally, I set the knife configuration options for my AWS EC2 account.

The configuration is parsed top-down, so the options here that overlap the knife.rb will be used instead.

In the Repository

In the repository, commit only the .chef/knife.rb and not the .chef/knife.local.rb. I recommend adding the local file to the .gitignore or VCS equivalent.

% echo .chef/knife.local.rb >> .gitignore
% git add .chef/knife.rb .gitignore
% git commit -m 'keep general knife.rb, local config is ignored'


There are many approaches to solving the issue of having shared Knife configuration for multiple people in a single repository. The real benefit here is that the configuration file is Ruby, which provides a lot of flexibility. Of course, when using someone else’s configuration examples, one should always read the code and understand it first :-).