google_dns_record_set has no Resource.UpdateFunc

[billf]

changes that are possible to make atomic cause recreation of a resource:

resource "google_dns_record_set" "cn-global-anycast-all" {
    managed_zone = "${var.dns-name}"
    name = "gcp.${var.dns-zone}"
    type = "A"
    ttl = 300
    rrdatas = ["${compact(split(",", terraform_remote_state.project.*.output.cn-global-anycast-addresses))}"]
}

even a simple re-order causes a record to be deleted and created:

-/+ google_dns_record_set.projectname
    managed_zone: "root-gcp-projectname" => "root-gcp-projectname"
    name:         "gcp.projectname.com." => "gcp.projectname.com."
    rrdatas.#:    "4" => "4"
    rrdatas.0:    "a.b.c.216" => "a.b.c.216"
    rrdatas.1:    "a.b.c.98"  => "a.b.c.98"
    rrdatas.2:    "a.b.c.136" => "a.b.c.143" (forces new resource)
    rrdatas.3:    "a.b.c.143" => "a.b.c.136" (forces new resource)
    ttl:          "300" => "300"
    type:         "A" => "A"

this change is not atomic and exposes a window during which a DNS record disappears.
this makes it unusable for anything besides create/destroy.

GCP API support for this exists:

// Change: An atomic update to a collection of ResourceRecordSets.
type Change struct {
    // Additions: Which ResourceRecordSets to add?
    Additions []*ResourceRecordSet `json:"additions,omitempty"`

    // Deletions: Which ResourceRecordSets to remove? Must match existing
    // data exactly.
    Deletions []*ResourceRecordSet `json:"deletions,omitempty"`

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.