BigIP LTM Pool - Update in place causing unnecessary destroy which fails as pool in use.

[scu-cmoore1]

Environment

• TMOS/Bigip Version: 16.1.4.1
• Terraform Version: v1.8.1
• Terraform bigip provider Version: v1.22.0

Summary

When updating a bigip_ltm_pool, Terraform says in place update but an error is returned saying the pool can't be deleted as it is in use.

Steps To Reproduce

resource "bigip_ltm_monitor" "monitor" {
  name   = "/Common/test_http_monitor"
  parent = "/Common/http"
}

resource "bigip_ltm_pool" "pool" {
  name                   = "/Common/test_pool"
  load_balancing_mode    = "least-connections"
  minimum_active_members = 1
  monitors               = [bigip_ltm_monitor.monitor.name]

  depends_on = [ 
    bigip_command.folder-command_create, 
    bigip_ltm_monitor.monitor 
  ]
}

resource "bigip_ltm_virtual_server" "http" {
    name        = "/Common/test_http"
    destination = "1.1.1.1"
    port        = 443
    source_address_translation = "automap"
    translate_address          = "enabled"
    translate_port             = "enabled"

    pool        = bigip_ltm_pool.pool.name

    profiles = [ "/Common/tcp", "/Common/http", "/Common/oneconnect" ]

    irules = [  ]

    depends_on = [ 
        bigip_ltm_pool.pool,
    ]
}

Now updating the pool resource will cause the error as it is in use by the virtual server http

Expected Behavior

The pool is successfully modified with the changes.

Actual Behavior

An error is thrown in Terraform

Terraform plan

  # module.production.module.netbox.bigip_ltm_pool.pool will be updated in-place
  ~ resource "bigip_ltm_pool" "pool" {
        id                     = "/Common/test_pool"
      ~ load_balancing_mode    = "round-robin" -> "least-connections"
        name                   = "/Common/test_pool"
      ~ service_down_action    = "none" -> "reselect"
        # (7 unchanged attributes hidden)
    }

Error

│ Error: 01070265:3: The Pool (/Common/test_pool) cannot be deleted because it is in use by a Virtual Server (/Common/test_http).
│
│   with module.production.module.test.bigip_ltm_pool.pool,
│   on modules/test_http/main.tf line 19, in resource "bigip_ltm_pool" "pool":
│   19: resource "bigip_ltm_pool" "pool" {

[pgouband]

Hi @scu-cmoore1,

I tested with version 1.22.1 the following with success.

resource "bigip_ltm_monitor" "monitor" {
  name   = "/Common/test_http_monitor"
  parent = "/Common/http"
}

resource "bigip_ltm_pool" "pool" {
  name                   = "/Common/test_pool"
  load_balancing_mode    = "least-connections-member"
  minimum_active_members = 1
  monitors               = [bigip_ltm_monitor.monitor.name]

  depends_on = [
    bigip_ltm_monitor.monitor 
  ]
}

resource "bigip_ltm_virtual_server" "http" {
    name        = "/Common/test_http"
    destination = "1.1.1.1"
    port        = 443
    source_address_translation = "automap"
    translate_address          = "enabled"
    translate_port             = "enabled"

    pool        = bigip_ltm_pool.pool.name

    profiles = [ "/Common/tcp", "/Common/http", "/Common/oneconnect" ]

    irules = [  ]

    depends_on = [ 
        bigip_ltm_pool.pool
    ]
}

Change LB mode:

resource "bigip_ltm_monitor" "monitor" {
  name   = "/Common/test_http_monitor"
  parent = "/Common/http"
}

resource "bigip_ltm_pool" "pool" {
  name                   = "/Common/test_pool"
  load_balancing_mode    = "ratio-member"
  minimum_active_members = 1
  monitors               = [bigip_ltm_monitor.monitor.name]

  depends_on = [
    bigip_ltm_monitor.monitor 
  ]
}

resource "bigip_ltm_virtual_server" "http" {
    name        = "/Common/test_http"
    destination = "1.1.1.1"
    port        = 443
    source_address_translation = "automap"
    translate_address          = "enabled"
    translate_port             = "enabled"

    pool        = bigip_ltm_pool.pool.name

    profiles = [ "/Common/tcp", "/Common/http", "/Common/oneconnect" ]

    irules = [  ]

    depends_on = [ 
        bigip_ltm_pool.pool
    ]
}

$ terraform plan -out pool
bigip_ltm_monitor.monitor: Refreshing state... [id=/Common/test_http_monitor]
bigip_ltm_pool.pool: Refreshing state... [id=/Common/test_pool]
bigip_ltm_virtual_server.http: Refreshing state... [id=/Common/test_http]

Terraform used the selected providers to generate the following execution plan.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  # bigip_ltm_pool.pool will be updated in-place
  ~ resource "bigip_ltm_pool" "pool" {
        id                     = "/Common/test_pool"
      ~ load_balancing_mode    = "least-connections-member" -> "ratio-member"
        name                   = "/Common/test_pool"
        # (7 unchanged attributes hidden)
    }

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

───────────────────────────────────────────────────────────────────────────────

Saved the plan to: pool

To perform exactly these actions, run the following command to apply:
    terraform apply "pool"

$ terraform apply "pool"
bigip_ltm_pool.pool: Modifying... [id=/Common/test_pool]
bigip_ltm_pool.pool: Modifications complete after 0s [id=/Common/test_pool]

Can you test with version 1.22.1?