Inspecting files on your Chef server with knife

Sometimes, you may want to peek into the files stored on your Chef server. You might not be sure about an implementation detail of that specific cookbook version, which is currently installed on your Chef server, and need to look it up. Knife can help you out by letting you show various aspects of the files stored on your Chef server.

Getting ready

Make sure that you have the iptables cookbook installed locally and uploaded on your Chef server.

1. Install the iptables community cookbook by executing the following command and code lines:

   mma@laptop:~/chef-repo $ knife cookbook site install iptables
   

   Installing iptables to /Users/mma/work/chef-repo/cookbooks
   ...TRUNCATED OUTPUT...

   Tip

   Take a look at the following error:

   ERROR: IOError: Cannot open or read ../chef-repo/cookbooks/iptables/metadata.rb!

   If you get the preceding error, your cookbook only has a metadata.json file. Make sure that you delete it and create a valid metadata.rb, file instead.

2. Upload the iptables cookbook on your Chef server by executing the following given command and code lines:

   mma@laptop:~/chef-repo $ knife cookbook upload iptables
   

   Uploading iptables       [0.14.0]
   Uploaded 1 cookbook.

How to do it...

Let's find out how knife can help you to look into a cookbook stored in your Chef server:

1. First, you want to find out the current version of the cookbook you're interested in. In our case, we're interested in the iptables cookbook:

   mma@laptop:~/work/chef_helpster $ knife cookbook show iptables
   iptables   0.14.0
   

2. Then, you can look up the definitions of the iptables cookbook, using the version number that you found out in the previous step:

   mma@laptop:~/chef-repo $ knife cookbook show iptables 0.14.0 definitions
   

     checksum:     45c0b77ff10d7177627694827ce47340
     name:         iptables_rule.rb
     path:         definitions/iptables_rule.rb
     specificity:  default
     url:          https://s3.amazonaws.com/opscode-platform...

3. Now, you can even show the contents of the iptables_rule.rb definition file, as stored on the server:

   mma@laptop:~/chef-repo $ knife cookbook show iptables 0.14.0 definitions iptables_rule.rb
   

   #
   # Cookbook Name:: iptables
   # Definition:: iptables_rule
   #
   #
   define :iptables_rule, :enable => true, :source => nil, :variables => {} do
   ...TRUNCATED OUTPUT...
   end

How it works...

The knife cookbook show subcommand helps you understand what exactly is stored on the Chef server. It lets you drill down into specific sections of your cookbooks and see the exact content of the files stored in your Chef server.

There's more...

Since Chef 11, you can pass patterns to the knife show command to tell it what exactly you want to see. Showing the contents of the iptables_rule definition can be done as follows, in addition to the way we described previously:

mma@laptop:~/work/chef_helpster $ knife show cookbooks/iptables/definitions/*

cookbooks/iptables/definitions/iptables_rule.rb:
#
# Cookbook Name:: iptables
# Definition:: iptables_rule
#
#
define :iptables_rule, :enable => true, :source => nil, :variables => {} do
...TRUNCATED OUTPUT...
end

See also

• To find some more examples on knife show, visit http://docs.chef.io/knife_show.html