From c85adf191a2d6a27cc4506d22655223316a96381 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Wed, 16 Dec 2020 14:10:51 -0500
Subject: [PATCH] modify ProvidedBy to indicate no provider needed

Because of the composition pattern used within core, we can't easily
remove a behavior from an embedded type. Rather than trying to
re-implement all necessary methods on the
NodePlannableResourceInstnaceOrphan to exclude orphaned data resources
from GraphNodeProviderConsumer, we can modify ProvidedBy to indicate
when there is no provider required.
---
 terraform/context_plan_test.go         | 52 ++++++++++++++++++++++++++
 terraform/node_resource_plan_orphan.go |  9 +++++
 terraform/transform_provider.go        |  8 +++-
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/terraform/context_plan_test.go b/terraform/context_plan_test.go
index 3731c69a0..60f84550c 100644
--- a/terraform/context_plan_test.go
+++ b/terraform/context_plan_test.go
@@ -6616,3 +6616,55 @@ resource "test_instance" "a" {
 		t.Fatal(diags.Err())
 	}
 }
+
+func TestContext2Plan_dataRemovalNoProvider(t *testing.T) {
+	m := testModuleInline(t, map[string]string{
+		"main.tf": `
+resource "test_instance" "a" {
+}
+`,
+	})
+
+	p := testProvider("test")
+	p.PlanResourceChangeFn = testDiffFn
+
+	state := states.NewState()
+	root := state.EnsureModule(addrs.RootModuleInstance)
+	root.SetResourceInstanceCurrent(
+		mustResourceInstanceAddr("test_instance.a").Resource,
+		&states.ResourceInstanceObjectSrc{
+			Status:       states.ObjectReady,
+			AttrsJSON:    []byte(`{"id":"a","data":"foo"}`),
+			Dependencies: []addrs.ConfigResource{},
+		},
+		mustProviderConfig(`provider["registry.terraform.io/hashicorp/test"]`),
+	)
+
+	// the provider for this data source is no longer in the config, but that
+	// should not matter for state removal.
+	root.SetResourceInstanceCurrent(
+		mustResourceInstanceAddr("data.test_data_source.d").Resource,
+		&states.ResourceInstanceObjectSrc{
+			Status:       states.ObjectReady,
+			AttrsJSON:    []byte(`{"id":"d"}`),
+			Dependencies: []addrs.ConfigResource{},
+		},
+		mustProviderConfig(`provider["registry.terraform.io/local/test"]`),
+	)
+
+	ctx := testContext2(t, &ContextOpts{
+		Config: m,
+		Providers: map[addrs.Provider]providers.Factory{
+			addrs.NewDefaultProvider("test"): testProviderFuncFixed(p),
+			// We still need to be able to locate the provider to decode the
+			// state, since we do not know during init that this provider is
+			// only used for an orphaned data source.
+			addrs.NewProvider("registry.terraform.io", "local", "test"): testProviderFuncFixed(p),
+		},
+		State: state,
+	})
+	_, diags := ctx.Plan()
+	if diags.HasErrors() {
+		t.Fatal(diags.Err())
+	}
+}
diff --git a/terraform/node_resource_plan_orphan.go b/terraform/node_resource_plan_orphan.go
index 6ac75c171..4653758a3 100644
--- a/terraform/node_resource_plan_orphan.go
+++ b/terraform/node_resource_plan_orphan.go
@@ -27,6 +27,7 @@ var (
 	_ GraphNodeAttachResourceConfig = (*NodePlannableResourceInstanceOrphan)(nil)
 	_ GraphNodeAttachResourceState  = (*NodePlannableResourceInstanceOrphan)(nil)
 	_ GraphNodeExecutable           = (*NodePlannableResourceInstanceOrphan)(nil)
+	_ GraphNodeProviderConsumer     = (*NodePlannableResourceInstanceOrphan)(nil)
 )
 
 func (n *NodePlannableResourceInstanceOrphan) Name() string {
@@ -48,6 +49,14 @@ func (n *NodePlannableResourceInstanceOrphan) Execute(ctx EvalContext, op walkOp
 	}
 }
 
+func (n *NodePlannableResourceInstanceOrphan) ProvidedBy() (addr addrs.ProviderConfig, exact bool) {
+	if n.Addr.Resource.Resource.Mode == addrs.DataResourceMode {
+		// indicate that this node does not require a configured provider
+		return nil, true
+	}
+	return n.NodeAbstractResourceInstance.ProvidedBy()
+}
+
 func (n *NodePlannableResourceInstanceOrphan) dataResourceExecute(ctx EvalContext) tfdiags.Diagnostics {
 	// A data source that is no longer in the config is removed from the state
 	log.Printf("[TRACE] NodePlannableResourceInstanceOrphan: removing state object for %s", n.Addr)
diff --git a/terraform/transform_provider.go b/terraform/transform_provider.go
index 2b3ebfea0..2b8728cd3 100644
--- a/terraform/transform_provider.go
+++ b/terraform/transform_provider.go
@@ -67,6 +67,7 @@ type GraphNodeProviderConsumer interface {
 	// ProvidedBy returns the address of the provider configuration the node
 	// refers to, if available. The following value types may be returned:
 	//
+	//   nil + exact true: the node does not require a provider
 	// * addrs.LocalProviderConfig: the provider was set in the resource config
 	// * addrs.AbsProviderConfig + exact true: the provider configuration was
 	//   taken from the instance state.
@@ -111,9 +112,14 @@ func (t *ProviderTransformer) Transform(g *Graph) error {
 	for _, v := range g.Vertices() {
 		// Does the vertex _directly_ use a provider?
 		if pv, ok := v.(GraphNodeProviderConsumer); ok {
+			providerAddr, exact := pv.ProvidedBy()
+			if providerAddr == nil && exact {
+				// no provider is required
+				continue
+			}
+
 			requested[v] = make(map[string]ProviderRequest)
 
-			providerAddr, exact := pv.ProvidedBy()
 			var absPc addrs.AbsProviderConfig
 
 			switch p := providerAddr.(type) {