Apply UseStateForUnknown for hosts of database instances

[zliang-akamai]

📝 Description

Resolve #2085

✔️ How to Test

First Step

Apply this TF config:

provider "linode" {}

resource "linode_database_postgresql_v2" "this" {
  label = "mydatabase"
  engine_id = "postgresql/16"
  region = "us-mia"
  type = "g6-standard-1"
  allow_list = ["0.0.0.0/0"]
}

provider "postgresql" {
  host        = linode_database_postgresql_v2.this.host_primary
  port        = linode_database_postgresql_v2.this.port
  database    = "defaultdb"
  superuser   = false
  username    = linode_database_postgresql_v2.this.root_username
  password    = linode_database_postgresql_v2.this.root_password
  sslrootcert = linode_database_postgresql_v2.this.ca_cert
  sslmode     = "require"
}

resource "postgresql_role" "this" {
  name     = "test_role"
  password = "test_password"
}

Second Step

Change the allow_list, then apply again.

provider "linode" {}

resource "linode_database_postgresql_v2" "this" {
  label = "mydatabase"
  engine_id = "postgresql/16"
  region = "us-mia"
  type = "g6-standard-1"
  allow_list = ["YOUR_IP_ADDRESS"] // change this to your IP
}

provider "postgresql" {
  host        = linode_database_postgresql_v2.this.host_primary
  port        = linode_database_postgresql_v2.this.port
  database    = "defaultdb"
  superuser   = false
  username    = linode_database_postgresql_v2.this.root_username
  password    = linode_database_postgresql_v2.this.root_password
  sslrootcert = linode_database_postgresql_v2.this.ca_cert
  sslmode     = "require"
}

resource "postgresql_role" "this" {
  name     = "test_role"
  password = "test_password"
}

[Copilot]

Pull Request Overview

This PR resolves issue #2085 by applying the UseStateForUnknown() plan modifier to the host_primary and host_secondary computed attributes in database resources. This prevents unnecessary updates to dependent resources when the database configuration changes but the host values remain the same.

Key changes:

• Added UseStateForUnknown() plan modifier to host attributes in PostgreSQL v2 database schema
• Added UseStateForUnknown() plan modifier to host attributes in MySQL v2 database schema

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
linode/databasepostgresqlv2/framework_resource_schema.go	Added plan modifiers to preserve host values during updates
linode/databasemysqlv2/framework_resource_schema.go	Added plan modifiers to preserve host values during updates

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[vshanthe]

LGTM

[ezilber-akamai]

Thanks for fixing this!

[zliang-akamai]

Blocked by #2176
We can't always use state for unknown because there are cases some attribute updates (e.g., changes of cluster_size may change the standby host (formerly secondary host)) will change host names. Also, secondary host has been renamed to standby host in the API response, so we may have to fix that before this PR.