Create Before Destroy

Adds create_before_destroy = true to security groups and ACM certificates. The replacement is created first; the old resource is destroyed after.

Why this rule exists

A security group that is still attached to a network interface cannot be deleted, so a change that forces replacement fails halfway through the apply. A certificate still bound to a listener has the same problem, with an outage while the listener has nothing to serve.

create_before_destroy is Terraform's own answer: create the new resource, move the references, then destroy the old one. It is a lifecycle argument, so it cannot be passed into an upstream module as a variable.

Related Terraform and OpenTofu issues

Affected resources

What this rule does

Adds a lifecycle { create_before_destroy = true } block to each matching resource (aws_security_group, aws_acm_certificate). When a change forces replacement, Terraform and OpenTofu create the new resource first and destroy the old one only after the replacement exists, so anything still attached to the old one keeps working through the swap. A resource that already carries a lifecycle block keeps it; the argument is merged in.

Before and after

Before (upstream module):

resource "aws_security_group" "this" {
  # ... resource configuration ...

  tags = var.tags
}

After (with Create Before Destroy applied):

resource "aws_security_group" "this" {
  # ... resource configuration ...

  tags = var.tags

  lifecycle {
    create_before_destroy = true
  }
}

The only change is the rule transformation. All existing arguments, outputs, and module behavior remain identical.

Known limits

• Only aws_security_group and aws_acm_certificate by default. Other resource types need the resource_types parameter set by your organization.
• Does not change what forces a replacement. The provider decides that; the rule changes only the order of create and destroy.
• Only .tf and .tofu files are read. Modules written in JSON syntax (.tf.json, .tofu.json) are left untouched.
• Only the module's own directory and its first-level modules/* submodules are processed. Modules that this module calls by source URL are separate downloads and are handled on their own request.

Default configuration

These are the values the rule ships with. They are not settable from a module source URL: ?rules= carries rule names only, so a per-request enable uses exactly the defaults below. Your organization sets them per rule, in its Baseline or in a ruleset, from the Operational Rules page; see Baseline rules and rulesets.

The rule's definition

The HCL this rule is written in - its parameters, their shipped defaults, and the transformers it runs - is published at lifecycle_create_before_destroy, alongside every other selectable rule.

How to enable

On a framework host, per request:

Add ?rules=lifecycle_create_before_destroy to your HTTPS module source, using the id exactly as written.

module "example" {
  source = "https://soc2.compliance.tf/terraform-aws-modules/s3-bucket/aws?version=5.0.0&rules=lifecycle_create_before_destroy"
}

A ?rules= list is either all bare names, which replace your organization's rules for that download, or all - prefixed names, which subtract from them. Mixing the two is refused with a 400 rather than silently treated as a replacement. To add this rule on top of your organization's rules instead, use ?add_rules=lifecycle_create_before_destroy; a bare ?rules= list cannot be combined with it, because a bare list already replaced the set there was something to add to.

The + add prefix was removed. It reached the registry only when written %2B, and a literal + in a query string decodes to a space everywhere, so ?rules=+lifecycle_create_before_destroy arrived as a bare name with a leading space — one step from silently replacing your organization's rules. Any +, in either spelling, is now a 400 naming ?add_rules=.

On your organization's host:

Add the rule to the organization's Baseline, which applies to every module served from the bare organization form <alias>.compliance.tf/<namespace>/<name>/<provider>, or to a named ruleset that one module selects with ?ruleset=<name> on the HTTPS form of that address. A project environment (<alias>.compliance.tf/<project>/<env>/<module>) serves the rules frozen in its bound snapshot instead: there the rule goes into the config draft and reaches the environment by promotion. On both organization forms ?rules= and ?add_rules= are refused with a 400 — including the subtractive - prefix — rather than dropped, so you cannot mistake an ignored override for an applied one. Change the configuration, not the URL. See Baseline rules and rulesets for the configuration flow, and registry resolution for how the address forms differ.

Break-glass path

On a framework host, add ?rules=-lifecycle_create_before_destroy to the module source URL and run terraform init -upgrade to fetch a copy without this rule. The copy in .terraform/modules/ stays until the next upgrade, so remove the override when you are done. On your organization's host the parameter is refused with a 400 rather than ignored. The rule comes from the organization's configuration: a Baseline rule applies to every module served from the bare organization form, so an admin disables it for the duration of the operation, or keeps it out of the Baseline and in a ruleset that only the modules needing it select. On a project environment the posture is the bound snapshot and its waivers. See Baseline rules and rulesets.

Failure modes