Policy

A policy is a configurable behavior you attach to a stack. Where a forma declares what resources should exist, a policy declares how formae should manage the stack’s lifecycle over time, without you having to run another apply. formae has two built-in policy types:

TTL policy: destroys a stack and its resources after a set duration.
Auto-reconcile policy: re-applies the stack’s declared state at a fixed interval, undoing out-of-band and incremental changes.

Inline vs. reusable policies

You can define a policy two ways. Inline policies live directly inside a stack definition. They belong to that stack alone and are deleted along with it.

new formae.Stack {
  label = "dev-environment"
  policies = new Listing {
    new formae.TTLPolicy {
      ttl = 4.h
      onDependents = "cascade"
    }
  }
}

Reusable policies are standalone objects, defined once and referenced from any number of stacks with .res. Changes to the policy propagate to every stack that references it.

local ephemeralPolicy = new formae.TTLPolicy {
  label = "ephemeral-1h"
  ttl = 1.h
  onDependents = "abort"
}

forma {
  ephemeralPolicy

  new formae.Stack {
    label = "dev-stack-1"
    policies = new Listing { ephemeralPolicy.res }
  }

  new formae.Stack {
    label = "dev-stack-2"
    policies = new Listing { ephemeralPolicy.res }
  }
}

Aspect	Inline	Reusable
Label	None	Required
Lifecycle	Follows the stack’s declaration; deleted with the stack	Independent, must be explicitly deleted
Sharing	Single stack only	Any number of stacks
Use case	One-off behavior	Consistent policy across stacks

Reach for a reusable policy as soon as you find yourself copying the same ttl or interval value into more than one stack. A single source of truth means one edit updates every stack that uses it.

Removing a policy

In reconcile mode, the applied forma is the source of truth for a stack’s policies, the same way it is for the stack’s resources:

Inline policy: re-apply the stack without the policy in its policies listing, and the policy is deleted.
Reusable policy: re-apply the stack without the .res reference, and the policy is detached from that stack. The standalone policy object itself lives on, attached to whatever other stacks still reference it, until it is destroyed.

This also means an inline policy added outside the forma (for example through an operator tool) does not survive the next reconcile of a stack the forma declares: declare it in the forma to keep it. Patch mode never touches policies you don’t mention.

Querying policies

formae inventory policies

Lists reusable policies only, since inline policies have no independent identity outside their stack. To see which policy, inline or reusable, is attached to a given stack, check the stack itself:

formae inventory stacks

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Guides

Concepts

Reference

Inline vs. reusable policies

Removing a policy

Querying policies

See also

​Inline vs. reusable policies

​Removing a policy

​Querying policies

​See also

Inline vs. reusable policies

Removing a policy

Querying policies

See also