AWS OpsWorks Stacks (Chef)

Chef Client

• Runs in local mode
• Relies on Chef-zero
  • lightweight local Chef server that uses local repository
  • allows to use chef search and data bags
• Platforms
  • Linux: Chef 12 (and earlier)
  • Windows: Chef 12.2
• Requires Ruby
  • Linux - installed by default
  • Windows - executable comes with Chef 12.2

Cookbook

• Associated with OpsWorks Stack
• Gets copied to the instance by OpsWorks
• Can be manually updated afterwards
  • Command -> Update Custom Cookbooks
•  Structure
  • attributes
  • recipes
  • templates
  • other
  • metada.rb
    • name
    • description
    • version
    • depends
      • other cookbook
    • ...

Cookbook Repository

• Linux: Git, Subversion
• Windows: Git
• S3 Archive
• Stack can have only one repository
  • It may contain multiple cookbooks
  • Use Berkshelf to workaround the limitation

Recipe

• Ruby code (.rb)
• Declaratively describes part of environment
  • similar to CF::Template
• Domain Specific Language (DSL)
  • e.g. package translated to appropriate package manager
• Associated with a layer
• Types
  • OpsWorks recipies
  • Custom recipies 
    
    • empty run_list by default
  • OpsWorks and Custom are run in 2 isolated environments 
    • no conflicts between the two
• Can be run manually
  • Command -> Execute Recipes

Attributes

• Key value pairs
• Used by Chef 11.10 and earlier versions
  • In Chef 12 depracted by Data Bags

Data Bag

• Collection of attributes (custom JSON)
• Chef concept
  
  • Normally uploaded to Chef server but here there is no Chef Server in OpsWorks Stacks
• Available on Chef 12
• Supersede "Attributes"
• Defined on Stack, Layer or Deployment level
• Example

  • search("aws_opsworks_layer").first

Run-List

• Ordered list of roles and recicpes to be run
• Empty run-list used for diagnostic purposes
  • exclude Chef issue 

Berkshelf

• Dependency manager for Chef
• Used to workaround "single cookbook repository" for a stack
  • Enable Berkshelf for the stack
  • Add Berksfile
    • Lists dependencies