Policy maps business and operational requirements, process, and workflow to settings and objects stored on the Chef Infra Server:
- Roles define server types, such as “web server” or “database server”
- Environments define process, such as “dev”, “staging”, or “production”
- Certain types of data—passwords, user account data, and other sensitive items—can be placed in data bags, which are located in a secure sub-area on the Chef Infra Server that can only be accessed by nodes that authenticate to the Chef Infra Server with the correct SSL certificates
- The cookbooks (and cookbook versions) in which organization-specific configuration policies are maintained
A cookbook version represents a set of functionality that is different from the cookbook on which it is based. A version may exist for many reasons, such as ensuring the correct use of a third-party component, updating a bug fix, or adding an improvement. A cookbook version is defined using syntax and operators, may be associated with environments, cookbook metadata, and/or run-lists, and may be frozen (to prevent unwanted updates from being made).
A cookbook version is maintained just like a cookbook, with regard to source control, uploading it to the Chef Infra Server, and how Chef Infra Client applies that cookbook when configuring nodes.
Data bags store global variables as JSON data. Data bags are indexed for searching and can be loaded by a cookbook or accessed during a search.
An environment is a way to map an organization’s real-life workflow to what can be configured and managed when using Chef Infra. This mapping is accomplished by setting attributes and pinning cookbooks at the environment level. With environments, you can change cookbook configurations depending on the system’s designation. For example, by designating different staging and production environments, you can then define the correct URL of a database server for each environment. Environments also allow organizations to move new cookbook releases from staging to production with confidence by stepping releases through testing environments before entering production.
A role is a way to define certain patterns and processes that exist across nodes in an organization as belonging to a single job function. Each role consists of zero (or more) attributes and a run-list. Each node can have zero (or more) roles assigned to it. When a role is run against a node, the configuration details of that node are compared against the attributes of the role, and then the contents of that role’s run-list are applied to the node’s configuration details. When a Chef Infra Client runs, it merges its own attributes and run-lists with those contained within each assigned role.
A Policyfile is a way to create immutable collections of cookbooks, cookbook dependencies, and attributes defined in a single document that is uploaded to the Chef Infra Server. The Policyfile is then associated with a group of nodes. When these nodes perform a Chef Infra Client run, they utilize recipes specified in the Policyfile.
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