awscc_ec2_ipam_pool - update to args has unexpected force new

[GlennChia]

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Terraform CLI and Terraform AWS Cloud Control Provider Version

Affected Resource(s)

• awscc_ec2_ipam_pool

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

First apply to create the resource works

data "aws_region" "current" {}

resource "awscc_ec2_ipam" "example" {
  operating_regions = [
    {
      region_name = data.aws_region.current.name
    }
  ]
}
resource "awscc_ec2_ipam_pool" "example" {
  address_family = "ipv4"
  description    = "example pool"
  ipam_scope_id  = awscc_ec2_ipam.example.private_default_scope_id
  locale         = data.aws_region.current.name
}

Second apply that just updates the description forces a new resources unexpectedly. This affects other argument updates of the pool as well

data "aws_region" "current" {}

resource "awscc_ec2_ipam" "example" {
  operating_regions = [
    {
      region_name = data.aws_region.current.name
    }
  ]
}
resource "awscc_ec2_ipam_pool" "example" {
  address_family = "ipv4"
  description    = "example pool update"
  ipam_scope_id  = awscc_ec2_ipam.example.private_default_scope_id
  locale         = data.aws_region.current.name
}

Debug Output

Panic Output

Expected Behavior

Expect an in-place update of the IPAM Pool without recreation

Actual Behavior

Forces a new IPAM Pool to be created. With the following snippet:

data.aws_region.current: Reading...
data.aws_region.current: Read complete after 0s [id=ap-southeast-1]
awscc_ec2_ipam.example: Refreshing state... [id=ipam-example]
awscc_ec2_ipam_pool.example: Refreshing state... [id=ipam-pool-example]

Terraform used the selected providers to generate the following execution plan. Resource
actions are indicated with the following symbols:
-/+ destroy and then create replacement

Terraform will perform the following actions:

  # awscc_ec2_ipam_pool.example must be replaced
-/+ resource "awscc_ec2_ipam_pool" "example" {
      + allocation_default_netmask_length = (known after apply)
      + allocation_max_netmask_length     = (known after apply)
      + allocation_min_netmask_length     = (known after apply)
      + allocation_resource_tags          = (known after apply)
      ~ arn                               = "arn:aws:ec2::111122223333:ipam-pool/ipam-pool-example" -> (known after apply)
      ~ auto_import                       = false -> (known after apply)
      + aws_service                       = (known after apply) # forces replacement
      ~ description                       = "example pool" -> "example pool update"
      ~ id                                = "ipam-pool-example" -> (known after apply)
      ~ ipam_arn                          = "arn:aws:ec2::111122223333:ipam/ipam-example" -> (known after apply)
      ~ ipam_pool_id                      = "ipam-pool-example" -> (known after apply)
      ~ ipam_scope_arn                    = "arn:aws:ec2::111122223333:ipam-scope/ipam-scope-example" -> (known after apply)
      ~ ipam_scope_type                   = "private" -> (known after apply)
      ~ pool_depth                        = 1 -> (known after apply)
      + provisioned_cidrs                 = (known after apply)
      + public_ip_source                  = (known after apply) # forces replacement
      + publicly_advertisable             = (known after apply) # forces replacement
      + source_ipam_pool_id               = (known after apply) # forces replacement
      ~ state                             = "create-complete" -> (known after apply)
      ~ state_message                     = "None" -> (known after apply)
      + tags                              = (known after apply)
        # (3 unchanged attributes hidden)
    }

Plan: 1 to add, 0 to change, 1 to destroy.

Steps to Reproduce

1. terraform apply with the following block

data "aws_region" "current" {}

resource "awscc_ec2_ipam" "example" {
  operating_regions = [
    {
      region_name = data.aws_region.current.name
    }
  ]
}
resource "awscc_ec2_ipam_pool" "example" {
  address_family = "ipv4"
  description    = "example pool"
  ipam_scope_id  = awscc_ec2_ipam.example.private_default_scope_id
  locale         = data.aws_region.current.name
}

2. Run terraform apply again with the following config that just updates the description forces a new resources unexpectedly. This affects other argument updates of the pool as well

data "aws_region" "current" {}

resource "awscc_ec2_ipam" "example" {
  operating_regions = [
    {
      region_name = data.aws_region.current.name
    }
  ]
}
resource "awscc_ec2_ipam_pool" "example" {
  address_family = "ipv4"
  description    = "example pool update"
  ipam_scope_id  = awscc_ec2_ipam.example.private_default_scope_id
  locale         = data.aws_region.current.name
}

Important Factoids

References

• PR with examples that work on create but force new on any update docs - ec2_ipam_pool #1137
• Update API is available here: ModifyIpamPool API action

[wellsiau-aws]

TF DEBUG output shows that the only detected changes are for tf_attribute_path=description:

@module=sdk.framework tf_provider_addr=registry.terraform.io/hashicorp/awscc tf_req_id=b0f34296-ded1-42e8-f685-f95bca6fe3de tf_resource_type=awscc_ec2_ipam_pool tf_attribute_path=description tf_rpc=PlanResourceChange timestamp=2023-09-11T16:46:38.496-0700

[wellsiau-aws]

IPAM Pool create only properties

    "createOnlyProperties": [
        "/properties/IpamScopeId",
        "/properties/SourceIpamPoolId",
        "/properties/Locale",
        "/properties/AddressFamily",
        "/properties/PubliclyAdvertisable",
        "/properties/PublicIpSource",
        "/properties/AwsService",
        "/properties/SourceResource"
    ],

[wellsiau-aws]

Terraform plan shows force replacement for these createOnlyProperties:

  # awscc_ec2_ipam_pool.example must be replaced
-/+ resource "awscc_ec2_ipam_pool" "example" {
      + allocation_default_netmask_length = (known after apply)
      + allocation_max_netmask_length     = (known after apply)
      + allocation_min_netmask_length     = (known after apply)
      + allocation_resource_tags          = (known after apply)
      ~ arn                               = "arn:aws:ec2::204034886740:ipam-pool/ipam-pool-0503a8371a95ab7d3" -> (known after apply)
      ~ auto_import                       = false -> (known after apply)
      + aws_service                       = (known after apply) # forces replacement
      ~ description                       = "example pool" -> "example pool longer"
      ~ id                                = "ipam-pool-0503a8371a95ab7d3" -> (known after apply)
      ~ ipam_arn                          = "arn:aws:ec2::204034886740:ipam/ipam-07f64eb9d3be41299" -> (known after apply)
      ~ ipam_pool_id                      = "ipam-pool-0503a8371a95ab7d3" -> (known after apply)
      ~ ipam_scope_arn                    = "arn:aws:ec2::204034886740:ipam-scope/ipam-scope-00e0e4271731e525b" -> (known after apply)
      ~ ipam_scope_type                   = "private" -> (known after apply)
      ~ pool_depth                        = 1 -> (known after apply)
      + provisioned_cidrs                 = (known after apply)
      + public_ip_source                  = (known after apply) # forces replacement
      + publicly_advertisable             = (known after apply) # forces replacement
      + source_ipam_pool_id               = (known after apply) # forces replacement
      + source_resource                   = (known after apply) # forces replacement
      ~ state                             = "create-complete" -> (known after apply)
      ~ state_message                     = "None" -> (known after apply)
      + tags                              = (known after apply)
        # (3 unchanged attributes hidden)
    }

Plan: 1 to add, 0 to change, 1 to destroy.

[wellsiau-aws]

These attributes are stored as null in the Terraform state file

    {
      "mode": "managed",
      "type": "awscc_ec2_ipam_pool",
      "name": "example",
      "provider": "provider[\"registry.terraform.io/hashicorp/awscc\"]",
      "instances": [
        {
          "schema_version": 1,
          "attributes": {
            "address_family": "ipv4",
            "allocation_default_netmask_length": null,
            "allocation_max_netmask_length": null,
            "allocation_min_netmask_length": null,
            "allocation_resource_tags": null,
            "arn": "arn:aws:ec2::204034886740:ipam-pool/ipam-pool-0503a8371a95ab7d3",
            "auto_import": false,
            "aws_service": null, # forces replacement
            "description": "example pool",
            "id": "ipam-pool-0503a8371a95ab7d3",
            "ipam_arn": "arn:aws:ec2::204034886740:ipam/ipam-07f64eb9d3be41299",
            "ipam_pool_id": "ipam-pool-0503a8371a95ab7d3",
            "ipam_scope_arn": "arn:aws:ec2::204034886740:ipam-scope/ipam-scope-00e0e4271731e525b",
            "ipam_scope_id": "ipam-scope-00e0e4271731e525b",
            "ipam_scope_type": "private",
            "locale": "us-east-1",
            "pool_depth": 1,
            "provisioned_cidrs": null,
            "public_ip_source": null, # forces replacement
            "publicly_advertisable": null, # forces replacement
            "source_ipam_pool_id": null, # forces replacement
            "source_resource": null, # forces replacement
            "state": "create-complete",
            "state_message": "None",
            "tags": null
          },
          "sensitive_attributes": [],
          "dependencies": [
            "awscc_ec2_ipam.example",
            "data.aws_region.current"
          ]
        }
      ]
    }

[wellsiau-aws]

GetResource using CCAPI confirms that these attributes are not included in the response:

• aws_service
• public_ip_source
• publicly_advertisable
• source_ipam_pool_id
• source_resource

See below for the output:

aws cloudcontrol get-resource --type-name AWS::EC2::IPAMPool --identifier ipam-pool-0503a8371a95ab7d3 --region us-east-1 | jq -r ".ResourceDescription.Properties" | jq "."

{
  "Locale": "us-east-1",
  "Description": "example pool",
  "IpamPoolId": "ipam-pool-0503a8371a95ab7d3",
  "IpamArn": "arn:aws:ec2::204034886740:ipam/ipam-07f64eb9d3be41299",
  "IpamScopeArn": "arn:aws:ec2::204034886740:ipam-scope/ipam-scope-00e0e4271731e525b",
  "IpamScopeType": "private",
  "IpamScopeId": "ipam-scope-00e0e4271731e525b",
  "ProvisionedCidrs": [],
  "PoolDepth": 1,
  "State": "create-complete",
  "AutoImport": false,
  "AddressFamily": "ipv4",
  "Arn": "arn:aws:ec2::204034886740:ipam-pool/ipam-pool-0503a8371a95ab7d3",
  "StateMessage": "None",
  "Tags": []
}

[wellsiau-aws]

I suspect the plan modifiers couldn't distinguish null value in Terraform state file versus no attributes on CCAPI GetResource response.

[ewbankkit]

It looks like we are falling foul of this behavior.

For example with aws_service, the planned value is unknown and the state value is null, so stringplanmodifier.RequiresReplace() returns true.

[wellsiau-aws]

@ewbankkit , with the lack of default values available on the schema, does this mean we need a custom plan modifiers?

[ewbankkit]

@wellsiau-aws I think using RequiresReplaceIfConfigured instead of RequiresReplace for the Optional+Computed attributes should work.

[wellsiau-aws]

you are right, I just tested this behavior on my local build for awscc_qbusiness_application

After I overcome this problem, I found a new behavior which I will describe on separate issue.