feat(cluster-connection): implement conterpart for cluster connections api in particular tgw

[dkropachev]

Closes #121

Cluster connection API was implemented in https://github.com/scylladb/siren/pull/10362. This PR implements terraform counterpart for it.

Tested:

main.tf :

resource "scylladbcloud_cluster" "aws" {
  name       = "AWS-statuspage-test-${random_string.postfix.result}"
  cloud      = "AWS"
  region     = "us-east-1"
  node_count = 3
  node_type  = "t3.micro"
  cidr_block = "172.31.0.0/24"
  enable_dns = true
  user_api_interface = "ALTERNATOR"
  alternator_write_isolation = "only_rmw_uses_lwt"
}

resource "scylladbcloud_cluster_connection" "aws-tgw-test" {
  cluster_id = scylladbcloud_cluster.aws.id
  name       = "aws-tgw-test"
  cidrlist = ["10.201.0.0/16"]
  type = "AWS_TGW_ATTACHMENT"
  datacenter = "AWS_US_EAST_1"
  status = "ACTIVE"
  data = {
    tgwid = "tgw-08461afa1119f390b"
    ramarn = "arn:aws:ram:us-east-1:043400831220:resource-share/be3b0395-1782-47cb-9ae4-6d3517c6a721"
  }
}

Apply:

➜  status-page-agent-provisioning git:(main) ✗ terraform apply                                                                                            
random_string.postfix: Refreshing state... [id=h74aFU4o]
scylladbcloud_cluster.aws: Refreshing state... [id=262]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # scylladbcloud_cluster_connection.aws-tgw-test will be created
  + resource "scylladbcloud_cluster_connection" "aws-tgw-test" {
      + cidrlist    = [
          + "10.201.0.0/16",
        ]
      + cluster_id  = 262
      + data        = {
          + "ramarn" = "arn:aws:ram:us-east-1:043400831220:resource-share/be3b0395-1782-47cb-9ae4-6d3517c6a721"
          + "tgwid"  = "tgw-08461afa1119f390a"
        }
      + datacenter  = "AWS_US_EAST_1"
      + external_id = (known after apply)
      + id          = (known after apply)
      + name        = "aws-tgw-test"
      + region      = (known after apply)
      + status      = "ACTIVE"
      + type        = "AWS_TGW_ATTACHMENT"
    }

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

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

scylladbcloud_cluster_connection.aws-tgw-test: Creating...
scylladbcloud_cluster_connection.aws-tgw-test: Still creating... [10s elapsed]
scylladbcloud_cluster_connection.aws-tgw-test: Still creating... [20s elapsed]
....
scylladbcloud_cluster_connection.aws-tgw-test: Still creating... [1m40s elapsed]
scylladbcloud_cluster_connection.aws-tgw-test: Creation complete after 1m46s [id=74]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

[charconstpointer]

is this needed here? this is a computed field that will be set by the provider, can you explain why user would like to provide the status?

[dkropachev]

Not necessary, removed.
When user creates connection he can pick status between ACTIVE and INACTIVE

[charconstpointer]

User can create a connection that will be INACTIVE by default?

[dkropachev]

Yap

[charconstpointer]

SetId sets the ID of the resource. If the value is blank, then the resource is destroyed. is the _ = data.Set("cluster_id", 0) needed in such case?

[dkropachev]

Question, what to do when resource is gone, while it is in the state? there are three options in this regard:

1. Throw an error on read. It results in error on next terraform apply or terraform refresh
2. Silently ignore. It results in having no error on apply and refresh, but object stays in state and if you want remove/recreate it, you need to go manually remove it from the state
3. Do data.SetId("") and return no error. Will result in having no error on apply and refresh and object been deleted from the state

From my perspective 3rd option produce best UX.

[dkropachev]

data.Set("cluster_id", 0) is not needed, removed

[charconstpointer]

why not return the error?

[dkropachev]

It is going to fail apply and refresh operation, which produce bad UX

[charconstpointer]

Why would it be bad UX to fail when reading misconfigured/malformed resource?

[dkropachev]

It is not malformed, it is deleted resource, on malformed it is going to return error

[dkropachev]

@charconstpointer, could you please take another look after rebase

[rjeczalik]

👍 LGTM, some less important comments