Merge pull request #21439 from hashicorp/jbardin/init-backend

init always prompts for migration with most remote backend configurations

command/init.go

@@ -675,6 +675,12 @@ func (c *InitCommand) backendConfigOverrideBody(flags rawFlags, schema *configsc
 		synthVals = make(map[string]cty.Value)
 	}
 
+	if len(items) == 1 && items[0].Value == "" {
+		// Explicitly remove all -backend-config options.
+		// We do this by setting an empty but non-nil ConfigOverrides.
+		return configs.SynthBody("-backend-config=''", synthVals), diags
+	}
+
 	for _, item := range items {
 		eq := strings.Index(item.Value, "=")
 

command/init_test.go

@@ -1,6 +1,7 @@
 package command
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -410,6 +411,113 @@ func TestInit_backendConfigKV(t *testing.T) {
 	}
 }
 
+func TestInit_backendConfigKVReInit(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-backend-config-kv"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	args := []string{"-backend-config", "path=test"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	ui = new(cli.MockUi)
+	c = &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	// a second init should require no changes, nor should it change the backend.
+	args = []string{"-input=false"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// make sure the backend is configured how we expect
+	configState := testDataStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+	cfg := map[string]interface{}{}
+	if err := json.Unmarshal(configState.Backend.ConfigRaw, &cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg["path"] != "test" {
+		t.Fatalf(`expected backend path="test", got path="%v"`, cfg["path"])
+	}
+
+	// override the -backend-config options by settings
+	args = []string{"-input=false", "-backend-config", ""}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// make sure the backend is configured how we expect
+	configState = testDataStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+	cfg = map[string]interface{}{}
+	if err := json.Unmarshal(configState.Backend.ConfigRaw, &cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg["path"] != nil {
+		t.Fatalf(`expected backend path="<nil>", got path="%v"`, cfg["path"])
+	}
+}
+
+func TestInit_backendConfigKVReInitWithConfigDiff(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-backend"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	args := []string{"-input=false"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	ui = new(cli.MockUi)
+	c = &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	// a second init with identical config should require no changes, nor
+	// should it change the backend.
+	args = []string{"-input=false", "-backend-config", "path=foo"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// make sure the backend is configured how we expect
+	configState := testDataStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+	cfg := map[string]interface{}{}
+	if err := json.Unmarshal(configState.Backend.ConfigRaw, &cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg["path"] != "foo" {
+		t.Fatalf(`expected backend path="foo", got path="%v"`, cfg["foo"])
+	}
+}
+
 func TestInit_targetSubdir(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := tempDir(t)
@@ -625,7 +733,7 @@ func TestInit_inputFalse(t *testing.T) {
 	}
 
 	// A missing input=false should abort rather than loop infinitely
-	args = []string{"-backend-config=path=bar"}
+	args = []string{"-backend-config=path=baz"}
 	if code := c.Run(args); code == 0 {
 		t.Fatal("init should have failed", ui.OutputWriter)
 	}

command/meta_backend.go

@@ -243,9 +243,8 @@ func (m *Meta) BackendForPlan(settings plans.Backend) (backend.Enhanced, tfdiags
 	if validateDiags.HasErrors() {
 		return nil, diags
 	}
-	configVal = newVal
 
-	configureDiags := b.Configure(configVal)
+	configureDiags := b.Configure(newVal)
 	diags = diags.Append(configureDiags)
 
 	// If the backend supports CLI initialization, do it.
@@ -521,12 +520,11 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, tfdiags.Di
 
 	// Potentially changing a backend configuration
 	case c != nil && !s.Backend.Empty():
-		// If we're not initializing, then it's sufficient for the configuration
-		// hashes to match, since that suggests that the static backend
-		// settings in the configuration files are unchanged. (The only
-		// record we have of CLI overrides is in the settings cache in this
-		// case, so we have no other source to compare with.
-		if !opts.Init && uint64(cHash) == s.Backend.Hash {
+		// We are not going to migrate if were not initializing and the hashes
+		// match indicating that the stored config is valid. If we are
+		// initializing, then we also assume the the backend config is OK if
+		// the hashes match, as long as we're not providing any new overrides.
+		if (uint64(cHash) == s.Backend.Hash) && (!opts.Init || opts.ConfigOverride == nil) {
 			log.Printf("[TRACE] Meta.Backend: using already-initialized, unchanged %q backend configuration", c.Type)
 			return m.backend_C_r_S_unchanged(c, cHash, sMgr)
 		}
@@ -922,9 +920,8 @@ func (m *Meta) backend_C_r_S_unchanged(c *configs.Backend, cHash int, sMgr *stat
 	if validDiags.HasErrors() {
 		return nil, diags
 	}
-	configVal = newVal
 
-	configDiags := b.Configure(configVal)
+	configDiags := b.Configure(newVal)
 	diags = diags.Append(configDiags)
 	if configDiags.HasErrors() {
 		return nil, diags
@@ -1051,9 +1048,8 @@ func (m *Meta) backendInitFromConfig(c *configs.Backend) (backend.Backend, cty.V
 	if validateDiags.HasErrors() {
 		return nil, cty.NilVal, diags
 	}
-	configVal = newVal
 
-	configureDiags := b.Configure(configVal)
+	configureDiags := b.Configure(newVal)
 	diags = diags.Append(configureDiags.InConfigBody(c.Config))
 
 	return b, configVal, diags
@@ -1082,9 +1078,8 @@ func (m *Meta) backendInitFromSaved(s *terraform.BackendState) (backend.Backend,
 	if validateDiags.HasErrors() {
 		return nil, diags
 	}
-	configVal = newVal
 
-	configureDiags := b.Configure(configVal)
+	configureDiags := b.Configure(newVal)
 	diags = diags.Append(configureDiags)
 
 	return b, diags