terraform crashes if provider returns value that does not conform to expected schema

[sebhoss]

Terraform Version

Terraform v1.4.0-dev
on linux_amd64

Terraform Configuration Files

# this is a simplified example
resource "example_resource" "testcase" {
  list_of_objects = [
    {
      name = "first"
      dynamic_attribute = 123 # NOTE: this is a dynamic type
    },
    {
      name = "second" # NOTE: dynamic_attribute is missing here
    },
  ]
}

Debug Output

https://gist.githubusercontent.com/sebhoss/ce219211c36bdb647893ddcb8ebfb8f0/raw/8714db3dc95b017aa7f08123c147829eb0d92357/logoutput.txt (crash is at the bottom)

Expected Behavior

I think Terraform Core should catch this issue sooner and tell the user that there is a problem with the provider rather than crash.

Actual Behavior

There is a crash in Terraform Core

Steps to Reproduce

1. git clone https://github.com/metio/terraform-provider-k8s.git
2. cd terraform-provider-k8s
3. git switch issue-147
4. make terratest TestAppsStatefulSetV1Resource

Note that the last step builds & installs the provider locally. I've only tested the install step (make install) on linux systems and it probably needs adjustments for mac/windows. Let me know if there is something I can do to help..

Additional Context

• The issue was discovered while trying to implement a dynamic type which is currently NOT supported as explained in Support Dynamic Type/Attributes/Parameters terraform-plugin-framework#147
• The reproducible example above runs tests in Terratest but the error remains when using Terraform directly
• I've created a PR at DONTMERGE: remove liveness_probe declaration to trigger terraform crash metio/terraform-provider-k8s#45 that triggers this crash
• The code for the custom type is at https://github.com/metio/terraform-provider-k8s/blob/main/internal/utilities/int_or_string.go
• The code for the resource that is involved in the example is at https://github.com/metio/terraform-provider-k8s/blob/main/internal/provider/resource_apps_stateful_set_v1.go
• The example usage of the resource from the log output is at https://github.com/metio/terraform-provider-k8s/blob/issue-147/examples/resources/k8s_apps_stateful_set_v1/resource.tf

References

hashicorp/terraform-plugin-framework#147

[sebhoss]

Forgot to add the output of terraform providers schema -json: https://gist.github.com/sebhoss/886a7588ffff04aca04f9a88a3748503 contains the schema for the resource in the example. It was created by running:

1. cd examples/resources/k8s_apps_stateful_set_v1
2. terraform providers schema -json | jq '.provider_schemas."localhost/metio/k8s".resource_schemas.k8s_apps_stateful_set_v1' > schema.json

[jbardin]

Thanks @sebhoss!

We are tracking the task to write more involved client-side validation in #30669.

Duplicate of #30669

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