Managing externally deleted resources in custom provider

[cbcoutinho]

I’m running into an issue with a custom provider using he Terraform Provider Framework.

The service I’m integrating with exposes the following endpoints:

GET /webhooks
POST /webooks
GET /webooks/{:id}
PUT /webooks/{:id}
DELETE /webooks/{:id}

The API is not consistent IMHO - deleting a resource via DELETE /webhooks/{:id} only removes the webhook from the collection (e.g. GET /webooks) - the resource is still available at GET /webhooks/{:id}.

Unfortunately I’m unable to change the API, so I want to work around this limitation in my custom provider. I need help determining a way of properly denoting a deleted resource so that Terraform knows the resource has been deleted and needs to be re-created. This is my current attempt, although it’s still not working.

Here is a snippet containing the relevant Read method from the webhook resource:

// Read refreshes the Terraform state with the latest data.
func (r *webhookResource) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) {

	var state WebhookResourceModel

	diags := req.State.Get(ctx, &state)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

// *** CHECKING FOR EXISTING WEBHOOK

	tflog.Info(ctx, "Reading all webhooks")

	exists := false
	webhooks, err := r.client.GetWebhooks()
	if err != nil {
		resp.Diagnostics.AddError(
			"Error reading webhooks",
			"Could not read webhook, unexpected error: "+err.Error(),
		)
		return
	}

	for _, w := range webhooks {
		tflog.Info(ctx, fmt.Sprintf("Found webhook[%s]: %+v", w.ID, w))
		if state.ID.ValueString() == w.ID {
			exists = true
		}
	}

    // *** How can you set state to "removed"?
	if !exists {
		tflog.Info(ctx, "Webhook does not exist!")
		state = WebhookResourceModel{}

		// Set empty state
		diags = resp.State.Set(ctx, &state)
		resp.Diagnostics.Append(diags...)
		if resp.Diagnostics.HasError() {
			return
		}
	}

// *** Assuming webhook exists

	tflog.Info(ctx, fmt.Sprintf("Reading webhook id: %s", state.ID.ValueString()))

	// Continue with normal reading of state...
}

Here’s a link to the provider for reference:

GitHub - cbcoutinho/terraform-provider-longship: Longship Terraform Provider

[cbcoutinho]

I found the solution to my problem here:

How should Read() signal that a resource has vanished from the API server?

I’m working on creating a new provider using the plugin framework SDK, and need some clarity on how a resource’s Read() and Update() methods should behave when a resource has vanished from the API server. Should Read() just flag all resource elements with Unknown: true (or Null: true?) in that case, or is there a different way to signal to the state that the resource no longer exists? Related to that, how should the resource Update() method handle these situations? The client library I’m usin…

func (r exampleResource) Read(ctx context.Context, req tfsdk.ReadResourceRequest, resp *tfsdk.ReadResourceResponse) {
  // ... other logic to call API/client ...

  if /* "resource not found" error */ {
    resp.State.RemoveResource()
    return
  }

  // ... other logic to update resp.State from API/client ...
}