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

Step 3: Create and Deploy a Custom Cookbook

The stack is not quite ready yet:

  • Your application needs some information to access to the MySQL database server and the Amazon S3 bucket, such as the database host name and the Amazon S3 bucket name .

  • You need to set up a database in the MySQL database server and create a table to hold the photos' metadata.

You could handle these tasks manually, but a better approach is to implement Chef recipe and have AWS OpsWorks Stacks run the recipe automatically on the appropriate instances. Chef recipes are specialized Ruby applications that AWS OpsWorks Stacks uses to perform tasks on instances such as installing packages or creating configuration files. They are packaged in a cookbook, which can contain multiple recipes and related files such as templates for configuration files. The cookbook is placed in a repository such as GitHub, and must have a standard directory structure. If you don't yet have a custom cookbook repository, see Cookbook Repositories for information on how to set one up.

For this example, the cookbook has been implemented for you and is stored in a public GitHub repository. The cookbook contains two recipes, appsetup.rb and dbsetup.rb, and a template file, db-connect.php.erb.

The appsetup.rb recipe creates a configuration file that contains the information that the application needs to access the database and the Amazon S3 bucket. It is basically a lightly modified version of the appsetup.rb recipe described in Connect the Application to the Database; see that topic for a detailed description. The primary difference is the variables that are passed to the template, which represent the access information.

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variables( :host => (deploy[:database][:host] rescue nil), :user => (deploy[:database][:username] rescue nil), :password => (deploy[:database][:password] rescue nil), :db => (deploy[:database][:database] rescue nil), :table => (node[:photoapp][:dbtable] rescue nil), :s3bucket => (node[:photobucket] rescue nil) )

The first four attributes define database connection settings, and are automatically defined by AWS OpsWorks Stacks when you create the MySQL instance.

There are two differences between these variables and the ones in the original recipe:

  • Like the original recipe, the table variable represents the name of the database table that is created by dbsetup.rb, and is set to the value of an attribute that is defined in the cookbook's attributes file.

    However, the attribute has a different name: [:photoapp][:dbtable].

  • The s3bucket variable is specific to this example and is set to the value of an attribute that represents the Amazon S3 bucket name, [:photobucket].

    [:photobucket] is defined by using custom JSON, as described later. For more information on attributes, see Attributes

For more information on attributes, see Attributes.

The dbsetup.rb recipe sets up a database table to hold each photo's metadata. It basically is a lightly modified version of the dbsetup.rb recipe described in Set Up the Database; see that topic for a detailed description.

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node[:deploy].each do |app_name, deploy| execute "mysql-create-table" do command "/usr/bin/mysql -u#{deploy[:database][:username]} -p#{deploy[:database][:password]} #{deploy[:database][:database]} -e'CREATE TABLE #{node[:photoapp][:dbtable]}( id INT UNSIGNED NOT NULL AUTO_INCREMENT, url VARCHAR(255) NOT NULL, caption VARCHAR(255), PRIMARY KEY (id) )'" not_if "/usr/bin/mysql -u#{deploy[:database][:username]} -p#{deploy[:database][:password]} #{deploy[:database][:database]} -e'SHOW TABLES' | grep #{node[:photoapp][:dbtable]}" action :run end end

The only difference between this example and the original recipe is the database schema, which has three columns that contain the ID, URL, and caption of each photo that is stored on the Amazon S3 bucket.

The recipes are already implemented, so all you need to do is deploy the photoapp cookbook to each instance's cookbook cache. AWS OpsWorks Stacks will then run the cached recipes when the appropriate lifecycle event occurs, as described later.

To deploy the photoapp cookbook

  1. On the AWS OpsWorks Stacks Stack page, click Stack Settings and then Edit.

  2. In the Configuration Management section:

    • Set Use custom Chef cookbooks to Yes.

    • Set Repository type to Git.

    • Set Repository URL to git://github.com/amazonwebservices/opsworks-example-cookbooks.git.

  3. On the Stack page, click Run Command, select the Update Custom Cookbooks stack command, and click Update Custom Cookbooks to install the new cookbook in the instances' cookbook caches.