kubernetes - enable surge upgrades by default during cluster creation

[varshavaradarajan]

Description: Now that surge upgrades is stable, enable surge upgrades by default as it is a better user experience during upgrades.

cc @adamwg

[andrewsomething]

Unfortunately, changing the default for a non-required attribute can be intrusive. Unless a user has explicitly set surge_upgrade in their configuration, they will be prompted to apply changes to existing clusters. E.g.

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  # digitalocean_kubernetes_cluster.foo will be updated in-place
  ~ resource "digitalocean_kubernetes_cluster" "foo" {
        id             = "21ea2185-bc6d-4a64-8797-e7898bc57d2f"
        name           = "foo"
      ~ An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  # digitalocean_kubernetes_cluster.foo will be updated in-place
  ~ resource "digitalocean_kubernetes_cluster" "foo" {
        id             = "21ea2185-bc6d-4a64-8797-e7898bc57d2f"
        name           = "foo"
      ~ surge_upgrade  = false -> true
        tags           = []
        # (12 unchanged attributes hidden)

        # (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.-> true
        tags           = []
        # (12 unchanged attributes hidden)

        # (1 unchanged block hidden)
    }

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

The user can add surge_upgrade = false explicitly to prevent the diff.

I'm not necessarily opposed to the change if we think surge upgrades will provide a better user experience in the long run, but want to make the consequences of the change clear.

[andrewsomething]

Data sources just report the state returned by the API for existing resources. You probably want to change the resource:

terraform-provider-digitalocean/digitalocean/resource_digitalocean_kubernetes_cluster.go

Line 49 in c1fb046

"surge_upgrade": {

[varshavaradarajan]

@andrewsomething - I'm not sure if I should change the schema version if I just provide a default value. I have done so. But, let me know if that's necessary.

[andrewsomething]

Generally it's not needed unless you are doing a state migration, but there is no problem with bumping it.

https://www.terraform.io/docs/extend/resources/state-migration.html