Chef + PowerShellDSC

chef-dsc.txt

How do Chef and DSC work together?

- dsc_script

    - A resource that allows you to create a configuration and embed that inside of your Chef recipe.

        - Point to external file with the DSC configuration
        - Embed a snippet of DSC syntax
    - WMF4+
    - Creates a configuration function and applies it via the LCM
    - Everything that you normally use in DSC is available
    - If you have multiple scripts, then it can be a little slower.

        - Set LCM to not allow reboot
        - Set LCM to Apply only. (monitoring will slow things down. if it is checking something, will not allow a new configuration to be applied and will cause chef-client run to fail
    - Synchronously parsing and getting verbose output and using that to determine what chef does
- dsc_resource

    - WMF5 +
    - The LCM refresh mode must be disabled
    - Individually call test, set and get methods under your own control

        - LCM = API you can call test and set methods individually
        - Much better performance
    - Cannot use composite resources with dsc_resource
- You cannot use dsc_script and dsc_resource on the same machine without changing the LCM state between them

What does Chef bring to the table

- Responsiveness - in DSC the only place you can do logic about state is inside that resource.

    - Chef builds the resource collection actively every time it runs on that client, and take into account current state of the node
- Notifications - Resources can notify/ subscribe to each other to run conditionally. In DSC this requires a custom resource because you cannot conditionally run one resource in response to the state of another resource.
- Environmental Data - being able to leverage Ohai data and make decisions based on it using variables

    - Roles - a bucket for a common configuration
    - Environments - pin cookbook versions to environments
    - Data bags - where to put arbitrary data to be used in your configuration
- Ecosystem

    - Testing tools, cloud API wrappers
    - Existing cookbooks with current enterprise use
    - Reporting and analytics data and management dashboard