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OpsWorks Databags & berkshelf

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OpsWorks Stacks Data Bag Reference

  • OpsWorks Stacks exposes settings to recipes as Chef data bag content.
  • A data bag is a Chef concept.
  • It is a global variable stored as JSON data on an instance
  • the JSON data is accessible from Chef.
  • Like data bag stores global variables as
    • app’s source URL
    • instance’s hostname
    • associated stack’s VPC identifier.
  • OpsWorks Stacks stores its data bags on each stack’s instances.
  • On Linux instances, data bags is at /var/chef/runs/run-ID/data_bags directory.
  • On Windows instances, data bags is at drive:\chef\runs\run-id\data_bags directory.
  • These directories include a set of data bags (subdirectories).
  • Each data bag contains zero or more data bag items, and are JSON-formatted files that having sets of data bag content.

Data bag content includes

  • String content
    • It follows Ruby syntax
    • can use single or double quotes
    • strings with special characters must have double quotes.
  • Boolean content
    • It is either true or false (no quotes).
  • Number content
    • It is either integer or decimal numbers, such as 4 or 2.5 (no quotes).
  • List content
    • Has the form of comma-separated values enclosed in square brackets (no quotes), such as [ ’80’, ‘443’ ]
  • JSON objects
    • which contain additional data bag content, such as “my-app”: {“elastic_ip”: null,…}.

Chef recipes can access through Chef search or directly, following

  • data bags
  • data bag items
  • data bag content

Search indexes to use to access a data bag through Chef search by OpsWorks Stacks

  • aws_opsworks_app, which represents a set of deployed apps for a stack.
  • aws_opsworks_command, which represents a set of commands that were run on a stack.
  • aws_opsworks_ecs_cluster, which represents a set of Amazon Elastic Container Service (Amazon ECS) cluster instances for a stack.
  • aws_opsworks_elastic_load_balancer, which represents a set of Elastic Load Balancing load balancers for a stack.
  • aws_opsworks_instance, which represents a set of instances for a stack.
  • aws_opsworks_layer, which represents a set of layers for a stack.
  • aws_opsworks_rds_db_instance, which represents a set of Amazon Relational Database Service (Amazon RDS) instances for a stack.
  • aws_opsworks_stack, which represents a stack.
  • aws_opsworks_user, which represents a set of users for a stack.

Berkshelf

  • Berkshelf is a dependency manager for Chef cookbooks.
  • Easily depend on community cookbooks
  • safely include community cookbooks in workflow.
  • It is included in ChefDK.
  • Running chef generate cookbook, by default, create a Berksfile in the root of the cookbook, alongside the cookbook’s metadata.rb.

Add cookbook’s dependencies to metadata, as

name 'my_first_cookbook'
version '0.1.0'
depends 'apt', '~> 5.0'

The default Berksfile will contain the following:

source 'https://supermarket.chef.io'metadata

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