Implementing Recipes for Chef 11.4 Stacks

The primary limitation of Chef 11.4 stacks is that recipes cannot use Chef search or data bags. However, AWS OpsWorks Stacks installs stack configuration and deployment attributes on each instance that contain much of the information that you would obtain with search, including the following:

AWS OpsWorks Stacks installs a current version of the stack configuration and deployment attributes on each instance for each lifecycle event, prior to starting the event's Chef run. The data is available to recipes through the standard node[:attribute][:child_attribute][...] syntax. For example, the stack configuration and deployment attributes includes the stack name, node[:opsworks][:stack][:name].

The following excerpt from one of the built-in recipes obtains the stack name and uses it to create a configuration file.

template '/etc/ganglia/gmetad.conf' do
  source 'gmetad.conf.erb'
  mode '0644'
  variables :stack_name => node[:opsworks][:stack][:name]
  notifies :restart, "service[gmetad]"
end

Many of the stack configuration and deployment attribute values contain multiple attributes. You must iterate over these attributes to obtain the information you need. The example below shows an excerpt from the stack configuration and deployment attributes, which are represented as JSON object for convenience. It contains a top-level attribute, deploy, which contains an attribute for each of the stack's apps, named with the app's short name.

{
  ...
  "deploy": {
    "app1_shortname": {
      "document_root": "app1_root",
      "deploy_to": "deploy_directory",
      "application_type": "php",
      ...
    },
    "app2_shortname": {
      "document_root": "app2_root",
      ...
    }
  },
  ...
}

Each app attribute contains a set of attributes that characterize the app. For example, the deploy_to attribute represents the app's deploy directory. The following excerpt sets the user, group, and path for each app's deploy directory.

node[:deploy].each do |application, deploy|
  opsworks_deploy_dir do
    user deploy[:user]
    group deploy[:group]
    path deploy[:deploy_to]
  end
  ...
end

For more information on the stack configuration and deployment attributes, see Customizing AWS OpsWorks Stacks. For more information on deploy directories, see Deploy Recipes.

Chef 11.4 stacks do not support data bags, but you can add arbitrary data to the stack configuration and deployment attributes by specifying custom JSON. Your recipes can then access the data by using standard Chef node syntax. For more information, see Using Custom JSON.

If you need the functionality of an encrypted data bag, one option is to store sensitive attributes in a secure location such as a private Amazon S3 bucket. Your recipes can then use the AWS Ruby SDK—which is installed on all AWS OpsWorks Stacks instances—to download the data from the bucket.

"Action": ["s3:GetObject"],
"Effect": "Allow",
"Resource": "arn:aws:s3:::amzn-s3-demo-bucket/*",