normalize missing provider names

The provider name coming from ProvidedBy may be resolved if it only
exists in the state. Make sure to strip the module and provider
prefixes for the provider name when adding missing providers.

terraform/context_apply_test.go

@@ -9099,3 +9099,117 @@ func TestContext2Apply_destroyWithProviders(t *testing.T) {
 		t.Fatalf("wrong final state\ngot:\n%s\nwant:\n%s", got, want)
 	}
 }
+
+func TestContext2Apply_providersFromState(t *testing.T) {
+	m := module.NewEmptyTree()
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+
+	for _, tc := range []struct {
+		name   string
+		state  *State
+		output string
+		err    bool
+	}{
+		{
+			name: "add implicit provider",
+			state: &State{
+				Modules: []*ModuleState{
+					&ModuleState{
+						Path: []string{"root"},
+						Resources: map[string]*ResourceState{
+							"aws_instance.a": &ResourceState{
+								Type: "aws_instance",
+								Primary: &InstanceState{
+									ID: "bar",
+								},
+								Provider: "provider.aws",
+							},
+						},
+					},
+				},
+			},
+			err:    false,
+			output: "<no state>",
+		},
+
+		// an aliased provider must be in the config to remove a resource
+		{
+			name: "add aliased provider",
+			state: &State{
+				Modules: []*ModuleState{
+					&ModuleState{
+						Path: []string{"root"},
+						Resources: map[string]*ResourceState{
+							"aws_instance.a": &ResourceState{
+								Type: "aws_instance",
+								Primary: &InstanceState{
+									ID: "bar",
+								},
+								Provider: "provider.aws.bar",
+							},
+						},
+					},
+				},
+			},
+			err: true,
+		},
+
+		// a provider in a module implies some sort of config, so this isn't
+		// allowed even without an alias
+		{
+			name: "add unaliased module provider",
+			state: &State{
+				Modules: []*ModuleState{
+					&ModuleState{
+						Path: []string{"root", "child"},
+						Resources: map[string]*ResourceState{
+							"aws_instance.a": &ResourceState{
+								Type: "aws_instance",
+								Primary: &InstanceState{
+									ID: "bar",
+								},
+								Provider: "module.child.provider.aws",
+							},
+						},
+					},
+				},
+			},
+			err: true,
+		},
+	} {
+
+		t.Run(tc.name, func(t *testing.T) {
+			ctx := testContext2(t, &ContextOpts{
+				Module: m,
+				ProviderResolver: ResourceProviderResolverFixed(
+					map[string]ResourceProviderFactory{
+						"aws": testProviderFuncFixed(p),
+					},
+				),
+				State: tc.state,
+			})
+
+			_, err := ctx.Plan()
+			if tc.err {
+				if err == nil {
+					t.Fatal("expected error")
+				} else {
+					return
+				}
+			}
+			if !tc.err && err != nil {
+				t.Fatal(err)
+			}
+
+			state, err := ctx.Apply()
+			if err != nil {
+				t.Fatalf("err: %s", err)
+			}
+
+			checkStateString(t, state, "<no state>")
+
+		})
+	}
+
+}

terraform/transform_provider.go

@@ -193,6 +193,11 @@ func (t *MissingProviderTransformer) Transform(g *Graph) error {
 		}
 
 		p := pv.ProvidedBy()
+		// this may be the resolved provider from the state, so we need to get
+		// the base provider name.
+		parts := strings.SplitAfter(p, "provider.")
+		p = parts[len(parts)-1]
+
 		key := ResolveProviderName(p, nil)
 		provider := m[key]
 
@@ -203,10 +208,12 @@ func (t *MissingProviderTransformer) Transform(g *Graph) error {
 
 		// we don't implicitly create aliased providers
 		if strings.Contains(p, ".") {
-			log.Println("[DEBUG] not adding missing provider alias", p)
+			log.Println("[DEBUG] not adding missing provider alias:", p)
 			continue
 		}
 
+		log.Println("[DEBUG] adding missing provider:", p)
+
 		// create the misisng top-level provider
 		provider = t.Concrete(&NodeAbstractProvider{
 			NameValue: p,