core: fix provider config inheritence for deeply nested modules (#6186)

The flattening process was not properly drawing dependencies between provider
nodes in modules and their parent provider nodes.

Fixes #2832
Fixes #4443
Fixes #4865

terraform/context_apply_test.go

@@ -1056,6 +1056,47 @@ func TestContext2Apply_moduleOrphanProvider(t *testing.T) {
 	}
 }
 
+func TestContext2Apply_moduleGrandchildProvider(t *testing.T) {
+	m := testModule(t, "apply-module-grandchild-provider-inherit")
+	p := testProvider("aws")
+	p.ApplyFn = testApplyFn
+	p.DiffFn = testDiffFn
+
+	var callLock sync.Mutex
+	called := false
+	p.ConfigureFn = func(c *ResourceConfig) error {
+		if _, ok := c.Get("value"); !ok {
+			return fmt.Errorf("value is not found")
+		}
+		callLock.Lock()
+		called = true
+		callLock.Unlock()
+
+		return nil
+	}
+
+	ctx := testContext2(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	if _, err := ctx.Plan(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if _, err := ctx.Apply(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	callLock.Lock()
+	defer callLock.Unlock()
+	if called != true {
+		t.Fatalf("err: configure never called")
+	}
+}
+
 // This tests an issue where all the providers in a module but not
 // in the root weren't being added to the root properly. In this test
 // case: aws is explicitly added to root, but "test" should be added to.

terraform/test-fixtures/apply-module-grandchild-provider-inherit/child/grandchild/main.tf

@@ -0,0 +1 @@
+resource "aws_instance" "foo" {}

terraform/test-fixtures/apply-module-grandchild-provider-inherit/child/main.tf

@@ -0,0 +1,3 @@
+module "grandchild" {
+  source = "./grandchild"
+}

terraform/test-fixtures/apply-module-grandchild-provider-inherit/main.tf

@@ -0,0 +1,7 @@
+provider "aws" {
+  value = "foo"
+}
+
+module "child" {
+  source = "./child"
+}

terraform/transform_provider.go

@@ -2,6 +2,7 @@ package terraform
 
 import (
 	"fmt"
+	"log"
 	"strings"
 
 	"github.com/hashicorp/go-multierror"
@@ -214,9 +215,11 @@ func (t *PruneProviderTransformer) Transform(g *Graph) error {
 		if pn, ok := v.(GraphNodeProvider); !ok || pn.ProviderName() == "" {
 			continue
 		}
-
 		// Does anything depend on this? If not, then prune it.
 		if s := g.UpEdges(v); s.Len() == 0 {
+			if nv, ok := v.(dag.NamedVertex); ok {
+				log.Printf("[DEBUG] Pruning provider with no dependencies: %s", nv.Name())
+			}
 			g.Remove(v)
 		}
 	}
@@ -340,7 +343,9 @@ func (n *graphNodeDisabledProviderFlat) ProviderName() string {
 
 // GraphNodeDependable impl.
 func (n *graphNodeDisabledProviderFlat) DependableName() []string {
-	return []string{n.Name()}
+	return modulePrefixList(
+		n.graphNodeDisabledProvider.DependableName(),
+		modulePrefixStr(n.PathValue))
 }
 
 func (n *graphNodeDisabledProviderFlat) DependentOn() []string {
@@ -349,13 +354,8 @@ func (n *graphNodeDisabledProviderFlat) DependentOn() []string {
 	// If we're in a module, then depend on our parent's provider
 	if len(n.PathValue) > 1 {
 		prefix := modulePrefixStr(n.PathValue[:len(n.PathValue)-1])
-		if prefix != "" {
-			prefix += "."
-		}
-
-		result = append(result, fmt.Sprintf(
-			"%s%s",
-			prefix, n.graphNodeDisabledProvider.Name()))
+		result = modulePrefixList(
+			n.graphNodeDisabledProvider.DependableName(), prefix)
 	}
 
 	return result
@@ -474,13 +474,7 @@ func (n *graphNodeProviderFlat) DependentOn() []string {
 	// If we're in a module, then depend on our parent's provider
 	if len(n.PathValue) > 1 {
 		prefix := modulePrefixStr(n.PathValue[:len(n.PathValue)-1])
-		if prefix != "" {
-			prefix += "."
-		}
-
-		result = append(result, fmt.Sprintf(
-			"%s%s",
-			prefix, n.graphNodeProvider.Name()))
+		result = modulePrefixList(n.graphNodeProvider.DependableName(), prefix)
 	}
 
 	return result