command/import: Fix allow-missing-config option

We previously intentionally removed support for the allow-missing-config
option to terraform import, requiring that all imported resources have
matching config. See #24412.

However, the option was not removed from the import command, and it is
widely used. This commit reintroduces support for importing with a
missing configuration by falling back to implying the provider FQN based
on the resource type.

Author: alisdair

command/import_test.go

@@ -601,7 +601,7 @@ func TestImport_providerConfigWithVarFile(t *testing.T) {
 	testStateOutput(t, statePath, testImportStr)
 }
 
-func TestImport_disallowMissingResourceConfig(t *testing.T) {
+func TestImport_allowMissingResourceConfig(t *testing.T) {
 	defer testChdir(t, testFixturePath("import-missing-resource-config"))()
 
 	statePath := testTempFile(t)
@@ -643,15 +643,15 @@ func TestImport_disallowMissingResourceConfig(t *testing.T) {
 		"bar",
 	}
 
-	if code := c.Run(args); code != 1 {
-		t.Fatalf("import succeeded; expected failure")
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
 	}
 
-	msg := ui.ErrorWriter.String()
-
-	if want := `Error: Resource test_instance.foo not found in the configuration.`; !strings.Contains(msg, want) {
-		t.Errorf("incorrect message\nwant substring: %s\ngot:\n%s", want, msg)
+	if !p.ImportResourceStateCalled {
+		t.Fatal("ImportResourceState should be called")
 	}
+
+	testStateOutput(t, statePath, testImportStr)
 }
 
 func TestImport_emptyConfig(t *testing.T) {

terraform/transform_import_state.go

@@ -30,27 +30,23 @@ func (t *ImportStateTransformer) Transform(g *Graph) error {
 			return fmt.Errorf("Module %s not found.", target.Addr.Module.Module())
 		}
 
-		// Get the resource config
-		rsCfg := modCfg.Module.ResourceByAddr(target.Addr.Resource.Resource)
-		if rsCfg == nil {
-			return fmt.Errorf("Resource %s not found in the configuration.", target.Addr)
-		}
-
-		// Get the provider FQN for the resource from the resource configuration
-		providerFqn := rsCfg.Provider
-
-		// This is only likely to happen in misconfigured tests.
-		if rsCfg == nil {
-			return fmt.Errorf("provider for resource %s not found in the configuration.", target.Addr)
+		providerAddr := addrs.AbsProviderConfig{
+			Module: target.Addr.Module.Module(),
 		}
 
-		// Get the provider local config for the resource
-		localpCfg := rsCfg.ProviderConfigAddr()
-
-		providerAddr := addrs.AbsProviderConfig{
-			Provider: providerFqn,
-			Alias:    localpCfg.Alias,
-			Module:   target.Addr.Module.Module(),
+		// Try to find the resource config
+		rsCfg := modCfg.Module.ResourceByAddr(target.Addr.Resource.Resource)
+		if rsCfg != nil {
+			// Get the provider FQN for the resource from the resource configuration
+			providerAddr.Provider = rsCfg.Provider
+
+			// Get the alias from the resource's provider local config
+			providerAddr.Alias = rsCfg.ProviderConfigAddr().Alias
+		} else {
+			// Resource has no matching config, so use an implied provider
+			// based on the resource type
+			rsProviderType := target.Addr.Resource.Resource.ImpliedProvider()
+			providerAddr.Provider = modCfg.Module.ImpliedProviderForUnqualifiedType(rsProviderType)
 		}
 
 		node := &graphNodeImportState{