Allow in-place update of PVC's storage request

[dak1n1]

Description

The Kubernetes API allows in-place updates of a PVC's spec.resources.requests.storage field.
This commit updates the PVC resource to allow the same.

A PVC's storage request may increase in-place, but the API does not allow it to decrease in place.
Therefore, the provider will recreate the PVC in the case that requests.storage decreases.
This will shield the user from this specific Kubernetes API error:

spec.resources.requests.storage: field can not be less than previous value

...And it provides an additional convenience by handling the delete/re-create automatically.

Acceptance tests

• Have you added an acceptance test for the functionality being added?
• Have you run the acceptance tests on this branch? (If so, please include the test log in a gist)

References

#602

Community Note

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[dak1n1]

I'm working on making a test for allow_volume_expansion that will test the storage request increase. Offhand, I'm not sure if it's possible to check if a resource has been deleted and re-created, but I'll do some research.

[alexsomesan]

Nice solution so far! Looks good to me :)

[dak1n1]

Thanks! I got some acceptance tests committed today. I tested them locally using minikube and GKE. The tests pass. TC test is running now too.

[dak1n1]

TC test passed. This is the result from a local test run:

# output from minikube run

😄  minikube v1.12.1 on Fedora 32
🐳  Preparing Kubernetes v1.18.3 on Docker 19.03.12 ...
🌟  Enabled addons: default-storageclass, storage-provisioner
🏄  Done! kubectl is now configured to use "minikube"

$ TF_ACC=true go test -v -run TestAccKubernetesPersistentVolumeClaim_expansion
=== RUN   TestAccKubernetesPersistentVolumeClaim_expansion
--- PASS: TestAccKubernetesPersistentVolumeClaim_expansion (74.33s)
PASS
ok      github.com/hashicorp/terraform-provider-kubernetes/kubernetes   74.405s
/home/dakini/go/src/github.com/hashicorp/terraform-provider-kubernetes


# output from GKE run

google_container_cluster.primary: Creation complete after 3m47s [id=projects/terraform-strategic-providers/locations/us-west1-a/clusters/tf-acc-test-42668e108886b9ea993c]
data.template_file.kubeconfig: Refreshing state...
local_file.kubeconfig: Creating...
local_file.kubeconfig: Creation complete after 0s [id=f7a77c1e96d9470e25fca44f9d793abd2781ddcb]

Apply complete! Resources: 5 added, 0 changed, 0 destroyed.


$ TF_ACC=true go test -v -run TestAccKubernetesPersistentVolumeClaim_expansion
=== RUN   TestAccKubernetesPersistentVolumeClaim_expansion
--- PASS: TestAccKubernetesPersistentVolumeClaim_expansion (67.18s)
PASS
ok      github.com/hashicorp/terraform-provider-kubernetes/kubernetes   67.267s
/home/dakini/go/src/github.com/hashicorp/terraform-provider-kubernetes

[alexsomesan]

LGTM!
Great work, @dak1n1! Very nicely done

[JordanP]

@dak1n1 Thank you so much for this ! Quick question (I could try myself but I am not sure how to quickly build the provider from the master branch): would this work for dynamic volume (volume_claim_template) ?

[dak1n1]

@JordanP unfortunately volume_claim_template is a part of the StatefulSet spec, which is set to ForceNew https://github.com/hashicorp/terraform-provider-kubernetes/blob/master/kubernetes/resource_kubernetes_stateful_set.go#L37 (which means if any field of Spec is modified, the resource will be replaced rather than modified in place).

[JordanP]

Ok, that's unfortunate for me :p I guess I can always work on a PR !

[ghost]

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