Overview

For an overview of basic policy concepts, please read policy engine in a nutshell. This document will delve further into what happens when a policy is applied in a given account.

An applied policy represents policy template code that is evaluated on a fixed schedule that is configured by the user applying the policy. The schedule can range from 15 minutes to weekly depending on the needs and requirements of the policy and will run on that schedule until terminated by a user.

Each evaluation of a given policy is stateless -- all data needed must be fetched every iteration and processed as needed.

Each applied policy runs in the context of a single RightScale account. The policy UI allows for applying a policy across multiple accounts, in which case an applied policy is created in each account selected.

Evaluation

Policy evaluation consists of a series of steps:

  • permissions check
  • data retrieval and transformation
  • validation
  • incident handling

Permissions Check

Permissions are checked if an optional permissions block` is supplied. If the user doesn't have sufficient permissions to take the actions specified, the policy is not applied. These permission checks are currently limited to user roles and actions within the CMP platform.

Data retrieval and transformation

Data retrieval is accomplished using the datasource and resource references. A policy can have any number of such references, each of which will typically correspond to a single API request to RightScale or an external API.

If a policy needs to act on data from multiple API calls, datasources may be chained together to have one feed into another. The debug log will list API requests as they happen as well as a snippet of the data downloaded.

Validation

Once all data has been gathered, the validations defined in the policy blockare evaluated. Validations consist of a series of checks on the data. Any items failing those checks are gathered together as violation data. Eachvalidateandvalidate_eachstatement occurs independently of the others and can produce 1 "incident". Multiplevalidatestatements can therefore produce multiple incidents. Avalidateorvalidate_eachstatement may have multiplecheckstatements. The first failedcheck` will result in that data being added as a violation.

If all checks pass and there is no violation data, then one of two things can happen. If no incident exists, nothing will happen and no incident will be generated. If an incident currently exists in a triggered state, it will proceed to a resolved state and any resolution actions defined will be run.

If there is violation data, that data is acted on by any escalate actions defined on the policy.

Incident Actions

In the case where a violation is detected and an incident already exists, the system evaluates the whole of the violation information to determine if any piece of data in the violation has changed, and if so then the incident actions defined in the escalation section will be run. This means that if an existing incident is updated with new violation data, the escalation actions such as email, run, or request_approval will be run again as if it were created for the first time.

Escalations will proceed until they come to a stopping point. This is a either a manual action such an approval_request, an error, or because all actions have finished. If multiple escalate fields are given, they will be evaluated in parallel and the status of each one gathered separately. The incident will continue to exist in a triggered state until the underlying conditions which triggered it change.

Termination

When an applied policy is terminated, any incidents are immediately moved to a terminated state. Any cloud workflow actions defined in run statements will run to completion unless manually terminated in the CWF console. No additional escalation or resolution actions will be taken.