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Budget Guardrails

Overview

Budget guardrails provide a mechanism for tracking current spend against a planned target, and taking appropriate actions to help control cost.

Current and forecast spend APIs are used to get information on the budget. This is currently available for AWS only.

Policy Types

Budget policies can be broadly classified into two categories:

Account-level settings for the target and the current spend etc, as well as permission settings in lockdown policies to restrict access.
Service/ Resource-level settings for taking action based on the budget state. These are defined in specific services and leverage existing controls such as Active and `Approved

Policy Types Description

Policy	Description
`AWS > Account > Budget > Enabled`	Determine whether budget reporting is enabled for the account or not.
`AWS > Account > Budget > Target`	The budget target for the AWS Account in US Dollars.
`AWS > Account > Budget > State`	Calculates the current status of the set budget. The default policy setting is generally sufficient.
`AWS > Account > Permissions > Lockdown > Budget`	Configure lockdown policies to restrict APIs based on the budget state (when the current spend exceeds a defined threshold).
`AWS > Account > Permissions > Lockdown > Budget > Restricted APIs`	A list of APIs that is restricted when the budget reaches the defined state.
`{provider} > {service} > {resource type} > Active > Budget`	The policy allows you to force {resource type} to the inactive status based on the current budget state, as defined in `AWS > Account > Budget > State`.
`{provider} > {service} > {resource type} > Approved > Budget`	The policy allows you to set {resource type} to Not approved based on the current budget state, as defined in `AWS > Account > Budget > State`.

Policy Types Definition

Account Level Policies

Account-level policies appear under AWS > Account > Budget in the type hierarchies, and are used to set and/ or view settings, values, and definitions that are shared by all services.
The state of the budget is determined by the interaction of several account level policies:
- The Budget > Enabled policy allows you to enable or disable budget checking. If set to Skip (the default), The budget control should not look up the budget data in the account.
The Budget > State policy a calculated value by default. It reflects the current state of the actual and forecast spend, as compared to the budget target set. The resource-level budget policies will use this policy to determine the actions to minimize cost.
The Budget > Target policy allows you to set the budget (allowed spend) for the account. The Budget > State will be set in relation to this amount.

Budget States

Guardrails defines named budget states. The enforcement policies and controls will refer to these states and will use the current state to determine when to take action.
The states are as follows:

State	Description
`Shutdown`	Budget is completely spent, or trending significantly over. No more money is available. All spending must cease, even if it results in degraded service.
`Critical`	Budget is completely spent, or trending significantly over. Urgent action is needed to reduce spend.
`Over`	Current or forecast spend exceeds the budget target.
`On target`	Current and forecast spend are in line with the budget target. No action is required.
`Under`	Current and forecast spend are lower than projected.
`Unused`	Current and forecast spend is so low that it appears that the account may not be in-use.
`Unknown`	Current and forecast spend is unknown for the account.

Note:

The default value for AWS > Account > Budget > Target is -1. If the policy value for the AWS > Account > Budget > Enabled policy is not Skip, and the AWS > Account > Budget > Target is < 0, the control should move to an invalid state, and informing the user to set the AWS > Account > Budget > Target policy to a positive integer value.

Account Level Preventive - Permissions

Account level preventive policies can be set to enforce preventative controls via AWS lockdown policies.
You can enable lockdowns via the AWS > Account > Permissions > Lockdown > Budget policy.
You can specify which api actions will be locked via the AWS > Account > Permissions > Lockdown > Budget > Restricted APIs policy, which allows you to set a list of IAM actions that are prevented for each state. For example:

critical:
  - ec2:RunInstance
  - ec2:StartInstance
  - rds:StartDB*
  - redshift:createcluster

Resource Level Policies

The budget policies defined as part of the Active control is used to determine whether the resource is active or inactive based on the current budget state of the account.
The budget policies defined as part of the Approved control is used to determine whether the resource is approved or unapproved based on the current budget state of the account.

The Active > Budget policy has a consistent form: {Provider} > {service} > {resource} > Active > Budget

AWS > EC2 > Instance > Active > Budget
AWS > RDS > DB Cluster > Active > Budget
AWS > Redshift > Cluster > Active > Budget

The values for this policy reflect when it should be inactive. The basic form is:

    Skip
    Force inactive if Budget > State is Over or higher
    Force inactive if Budget > State is Critical or higher
    Force inactive if Budget > State is Shutdown

The Approved > Budget policy has a consistent form: {Provider} > {service} > {resource} > Approved > Budget

AWS > EC2 > Instance > Approved > Budget
AWS > RDS > DB Cluster > Approved > Budget
AWS > Redshift > Cluster > Approved > Budget

The values for this policy reflect when it should be unapproved. The basic form is:

    Skip
    Unapproved if Budget > State is Over or higher
    Unapproved if Budget > State is Critical or higher
    Unapproved if Budget > State is Shutdown

Example: AWS > Account > Budget > Enabled

First, assume that the monthly actual spent becomes $ 1001. The following policies have been configured in Guardrails:

AWS > Account > Budget > Enabled is set to Check: Budget > State is on Target or below.
AWS > Account > Budget > Targe is set to 1000.
AWS > Account > Budget > State is calculated to Over.

In order, these policies will evaluate account spending is over the budget and has entered the Over state. The policy evaluation of Budget > Enabled results the control being in ALARM state.