azurerm_cdn_frontdoor_rule does not allow cache_duration of "00:00:00".

[ingara]

Is there an existing issue for this?

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Terraform Version

1.3.7

AzureRM Provider Version

3.40.0

Affected Resource(s)/Data Source(s)

azurerm_cdn_frontdoor_rule

Terraform Configuration Files

resource "azurerm_cdn_frontdoor_rule" "example" {
  cdn_frontdoor_rule_set_id = "/subscriptions/..."
  name                      = "disableDefaultCaching"
  order                     = 0

  actions {
    route_configuration_override_action {
      cdn_frontdoor_origin_group_id = "/subscriptions/..."
      cache_behavior                = "OverrideIfOriginMissing"
      cache_duration                = "00:00:00"
    }
  }
}

Debug Output/Panic Output

Error: "actions.0.route_configuration_override_action.0.cache_duration" must be longer than zero seconds, got "00:00:00"

Expected Behaviour

It should successfully create the rule with duration set to 0 seconds.

This is possible in the Azure Portal, and is according to Microsoft the only way to "disable" the default caching behaviour for responses which do not have cache headers.

Relevant portion of the docs (https://learn.microsoft.com/en-us/azure/frontdoor/front-door-rules-engine-actions?tabs=portal&pivots=front-door-standard-premium#properties – under "Cache duration"):

For a value of 0 seconds, the CDN caches the content, but must revalidate each request with the origin server.

The relevant code is at

terraform-provider-azurerm/internal/services/cdn/validate/front_door_validation_helpers.go

Lines 53 to 55 in 48cd750

	if v == "00:00:00" {
	return nil, []error{fmt.Errorf(`%q must be longer than zero seconds, got %q`, k, v)}
	}

As far as I can tell this explicit check should be removed.

Actual Behaviour

Validation error.

Steps to Reproduce

1. terraform validate

Important Factoids

No response

References

• https://learn.microsoft.com/en-us/azure/frontdoor/front-door-rules-engine-actions?tabs=portal&pivots=front-door-standard-premium#properties

[rcskosir]

@ingara Thank you for taking the time to open this issue. Please subscribe to PR #23384 created by @WodansSon for this issue.

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