Can't specify empty set of taints on GKE node pools

[shields-fn]

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Terraform Version

Terraform v0.12.6

• provider.google v2.12.0
• provider.google-beta v2.12.0

Affected Resource(s)

• google_container_cluster
• google_container_node_pool

Terraform Configuration Files

Before:

resource "google_container_cluster" "test" {
  provider = "google-beta"

  name               = "test"
  location           = "us-central1-b"
  initial_node_count = 1

  node_config {
    taint {
      key    = "K"
      value  = "V"
      effect = "NO_SCHEDULE"
    }
  }
}

After:

resource "google_container_cluster" "test" {
  provider = "google-beta"

  name               = "test"
  location           = "us-central1-b"
  initial_node_count = 1

  node_config {
  }
}

Debug Output

https://gist.github.com/shields-fn/641926b7b3a68adc70e42dad82094563

Panic Output

None

Expected Behavior

The node pool should have been destroyed and recreated without Kubernetes taints.

Actual Behavior

Nothing; terraform plan reports that no changes are needed.

Steps to Reproduce

1. terraform apply
2. Remove taint section of config
3. terraform apply

[rileykarson]

Due to how this is implemented (as an Optional + Computed field), it'll end up being a breaking change to allow users to define empty taints.

GKE tends to add taints at will based on using certain features, so I'm not sure that requiring users to always define their node pool taints in their TF config is a great idea, although sticking unnecessary taints on users' node pools isn't great either.

[nicktrav]

Not sure I agree with the assessment that this isn't a bug, irrespective of whether a fix would be a breaking change or not.

Concretely, we had a node pool defined with a taint. I then removed the taint in terraform but this did nothing to the node pool. The taint remains. At this point, my state doesn't match my intent.

Are there any known workarounds in the interim?

[rileykarson]

Yeah, this falls somewhere in the middle of both. Since functionality that should work doesn't, this is a bug. On the other hand, we expect removal to not work right now due to the implementation, and making it work is an enhancement. I lean a bit more closely towards it being an enhancement for our issue classification purposes.

Regardless of that classification, fixing taints will be part of 3.0.0.

Unfortunately, there are no known workarounds other than possibly declaring a useless taint, or manually reconciling the resource out of band with gcloud or the UI.

[nicktrav]

@rileykarson - noticed this was closed. Will this be in a 2.x release of the provider?

[rileykarson]

This will appear in the 3.0.0 release. Timing isn't guaranteed, but the anticipated date(s) are 2019/11/19 or 2019/11/26.

https://github.com/terraform-providers/terraform-provider-google/blob/master/website/docs/version_3_upgrade.html.markdown#taint-field-is-now-authoritative-when-set contains some justification for why it's there and couldn't have landed in a 2.X release. While minor, there were technically 2 breaking changes made on the field.

[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 feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 [email protected]. Thanks!