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AWS OpsWorks
User Guide (API Version 2013-02-18)

Step 14: Update the Cookbook to Use Iteration

Update your cookbook by adding a recipe that uses iteration, a technique that repeats recipe code multiple times. This recipe displays messages in the log for a data bag item that contains multiple contents.

To update the cookbook on the instance and to run the new recipe

  1. On your local workstation, in the recipes subdirectory in the opsworks_cookbook_demo directory, create a file named iteration_demo.rb that contains the following code:

    stack = search("aws_opsworks_stack").first
    Chef::Log.info("********** Content of 'custom_cookbooks_source' **********")
    
    stack["custom_cookbooks_source"].each do |content|
      Chef::Log.info("********** '#{content}' **********")
    end

    Note

    Writing the preceding recipe code is shorter, more flexible, and less error-prone than writing the following recipe code that does not use iteration:

    stack = search("aws_opsworks_stack").first
    Chef::Log.info("********** Content of 'custom_cookbooks_source' **********")
    
    Chef::Log::info("********** '[\"type\", \"#{stack['custom_cookbooks_source']['type']}\"]' **********")
    Chef::Log::info("********** '[\"url\", \"#{stack['custom_cookbooks_source']['url']}\"]' **********")
    Chef::Log::info("********** '[\"username\", \"#{stack['custom_cookbooks_source']['username']}\"]' **********")
    Chef::Log::info("********** '[\"password\", \"#{stack['custom_cookbooks_source']['password']}\"]' **********")
    Chef::Log::info("********** '[\"ssh_key\", \"#{stack['custom_cookbooks_source']['ssh_key']}\"]' **********")
    Chef::Log::info("********** '[\"revision\", \"#{stack['custom_cookbooks_source']['revision']}\"]' **********")
  2. At the terminal or command prompt, use the tar command create a new version of the opsworks_cookbook_demo.tar.gz file, which contains the opsworks_cookbook_demo directory and its updated contents.

  3. Upload the updated opsworks_cookbook_demo.tar.gz file to your S3 bucket.

  4. Follow the procedures in Step 5: Update the Cookbook on the Instance and Run the Recipe to update the cookbook on the instance and to run the recipe. In the "To run the recipe" procedure, for Recipes to execute, type opsworks_cookbook_demo::iteration_demo.

To test the recipe

  1. With the Running command execute_recipes page displayed from the previous procedures, for cookbooks-demo1, for Log, choose show. The execute_recipes log page is displayed.

  2. Scroll down through the log and find entries that look similar to the following:

    [2015-11-16T19:56:56+00:00] INFO: ********** Content of 'custom_cookbooks_source' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["type", "s3"]' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["url", "https://s3.amazonaws.com/opsworks-demo-bucket/opsworks_cookbook_demo.tar.gz"]' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["username", "secret-key-value"]' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["password", "secret-access-key-value"]' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["ssh_key", nil]' **********
    [2015-11-16T19:56:56+00:00] INFO: ********** '["revision", nil]' **********

    This recipe displays messages in the log for a data bag item that contains multiple contents. The data bag item is in the aws_opsworks_stack data bag. The data bag item has content named custom_cookbooks_source. Inside of this content are six contents named type, url, username, password, ssh_key, and revision; their values are also displayed.

In the next step, you will update the cookbook to run recipe code only if certain conditions are met.