Defining cookbook dependencies

Make sure you have a cookbook named my_cookbook, and the run_list of your node includes my_cookbook, as described in the Creating and using cookbooks recipe in this chapter.

Edit the metadata of your cookbook in the file cookbooks/my_cookbook/metadata.rb to add a dependency to the build-essential cookbook:

mma@laptop:~/chef-repo $ subl cookbooks/my_cookbook/metadata.rb
...
depends 'build-essential', '>= 7.0.3'

If you want to use a feature of another cookbook inside your cookbook, you will need to include the other cookbook in your recipe using the include_recipe directive:

include_recipe 'build-essential'

To tell the Chef server that your cookbook requires the build-essential cookbook, you need to declare that dependency in the metadata.rb file. If you uploaded all the dependencies to your Chef server either using knife cookbook upload my_cookbook --include-dependencies or berks install and berks upload, as described in the Managing cookbook dependencies with Berkshelf recipe in this chapter, the Chef server will then send all the required cookbooks to the node.

The depends function call tells the Chef server that your cookbook depends on a version greater than or equal to 7.0.3 of the build-essential cookbook.

You may use any of these version constraints with depends calls:

If you include another recipe inside your recipe, without declaring the cookbook dependency in your metadata.rb file, Foodcritic will warn you:

mma@laptop:~/chef-repo $ foodcritic cookbooks/my_cookbook
FC007: Ensure recipe dependencies are reflected in cookbook metadata: cookbooks/my_cookbook/recipes/default.rb:9

Additionally, you can declare conflicting cookbooks through the conflicts call:

conflicts "nginx"

Of course, you can use version constraints exactly the same way you did with depends.