Support in-place instance ephemeral and floating IP changes

[askfongjojo]

Overview

Currently, a change in the instance external IP spec results in a forced replacement in terraform apply, e.g.

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:

  # oxide_instance.mysql[0] must be replaced
-/+ resource "oxide_instance" "mysql" {
      ~ external_ips       = [
          - { # forces replacement
              - id   = "6c75764b-0350-4dfe-9f13-920ae0c3e75f" -> null
              - type = "floating" -> null
            },
            # (1 unchanged element hidden)
        ]
      ~ id                 = "8bc31b24-22c7-4d40-82aa-22a603564abe" -> (known after apply)
        name               = "mysql-0"
      ~ network_interfaces = [
          - {
              - description   = "Default NIC" -> null
              - id            = "93193c53-74f9-4de3-8311-0a788a1706c6" -> null
              - ip_address    = "172.30.0.11" -> null
              - mac_address   = "A8:40:25:F0:00:06" -> null
              - name          = "default" -> null
              - primary       = true -> null
              - subnet_id     = "11a7986f-475d-4bf1-bb96-bacb3dbeec3a" -> null
              - time_created  = "2025-01-08 19:50:49.67032 +0000 UTC" -> null
              - time_modified = "2025-01-08 19:50:49.67032 +0000 UTC" -> null
              - vpc_id        = "cd36ca5d-b536-4316-8b26-e330cafa3b9f" -> null
            },
          + {
              + description   = "Default NIC"
              + id            = (known after apply)
              + ip_address    = (known after apply)
              + mac_address   = (known after apply)
              + name          = "default"
              + primary       = (known after apply)
              + subnet_id     = "11a7986f-475d-4bf1-bb96-bacb3dbeec3a"
              + time_created  = (known after apply)
              + time_modified = (known after apply)
              + vpc_id        = "cd36ca5d-b536-4316-8b26-e330cafa3b9f"
            },
        ]
      ~ time_created       = "2025-01-08 19:50:49.429581 +0000 UTC" -> (known after apply)
      ~ time_modified      = "2025-01-08 19:50:49.429581 +0000 UTC" -> (known after apply)
        # (8 unchanged attributes hidden)
    }

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

There is API support to dynamically attach/detach floating IP and ephemeral IP without the need to stop/start the instance. We can improve the user experience and instance uptime by having terraform apply make those external IP changes without recreating instnaces.

Implementation details

No response

Anything else you would like to add?

No response

[karencfv]

@askfongjojo I think there is an issue with the detach ephemeral IP endpoint. The attach one takes the name or ID of the IP pool to take the IP from, but the detach endpoint doesn't. Does it just detach everything? Is this the expected behaviour? If not, then I think that would block this issue for now.

[sudomateo]

@askfongjojo I think there is an issue with the detach ephemeral IP endpoint. The attach one takes the name or ID of the IP pool to take the IP from, but the detach endpoint doesn't. Does it just detach everything? Is this the expected behaviour? If not, then I think that would block this issue for now.

I didn't see this comment until after I already started working on this issue in #381. An instance can only have 1 ephemeral external IP attached at a time. That means the API will have the following behavior.

• instance_ephemeral_ip_attach - Attach an ephemeral external IP to the instance, overwriting the existing ephemeral external IP, if any.
• instance_ephemeral_ip_detach - Detach an ephemeral external IP, if any.

[askfongjojo]

Yes, unlike floating IP, each instance can have no more than one ephemeral IP. We can model after how it works on the web console which already makes use of the attach/detach APIs.

[karencfv]

Thanks for the clarification!