Add a warning when multiple likely forks of a provider are detected (#1009)

Signed-off-by: Christian Mesh <christianmesh1@gmail.com>

CHANGELOG.md

@@ -33,6 +33,7 @@ ENHANCEMENTS:
 * state: Provider addresses in the statefile referring to registry.terraform.io will be treated as referring to registry.opentofu.org unless the full provider address is specified in the config or `OPENTOFU_STATEFILE_PROVIDER_ADDRESS_TRANSLATION` is set to `0`. ([#773](https://github.com/opentofu/opentofu/pull/773))
 * The default provider namespace has been changed from "hasicorp" to "opentofu". This only impacts providers that do not explicitly have a namespace set, ex "aws" vs "hasicorp/aws". This change should be transparent and not require action to be taken by users.
 * init: Ensured that the `tofu init` command has consistent spelling of the word `initialization` in its output. ([#855](https://github.com/opentofu/opentofu/pull/855/files))
+* init: A warning is now emitted when two providers who share the same name are detected.  This can help prevent misconfigurations when switching a project to use a fork of a provider. ([#1009](https://github.com/opentofu/opentofu/pull/1009))
 
 BUG FIXES:
 

internal/command/init.go

@@ -546,7 +546,13 @@ func (c *InitCommand) getProviders(ctx context.Context, config *configs.Config,
 		reqs = reqs.Merge(stateReqs)
 	}
 
+	potentialProviderConflicts := make(map[string][]string)
+
 	for providerAddr := range reqs {
+		if providerAddr.Namespace == "hashicorp" || providerAddr.Namespace == "opentofu" {
+			potentialProviderConflicts[providerAddr.Type] = append(potentialProviderConflicts[providerAddr.Type], providerAddr.ForDisplay())
+		}
+
 		if providerAddr.IsLegacy() {
 			diags = diags.Append(tfdiags.Sourceless(
 				tfdiags.Error,
@@ -559,6 +565,20 @@ func (c *InitCommand) getProviders(ctx context.Context, config *configs.Config,
 		}
 	}
 
+	for name, addrs := range potentialProviderConflicts {
+		if len(addrs) > 1 {
+			diags = diags.Append(tfdiags.Sourceless(
+				tfdiags.Warning,
+				"Potential provider misconfiguration",
+				fmt.Sprintf(
+					"OpenTofu has detected multiple providers of type %s (%s) which may be a misconfiguration.\n\nIf this is intentional you can ignore this warning",
+					name,
+					strings.Join(addrs, ", "),
+				),
+			))
+		}
+	}
+
 	previousLocks, moreDiags := c.lockedDependencies()
 	diags = diags.Append(moreDiags)
 

internal/command/init_test.go

@@ -1631,6 +1631,71 @@ func TestInit_getProviderDetectedLegacy(t *testing.T) {
 	}
 }
 
+func TestInit_getProviderDetectedDuplicate(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := t.TempDir()
+	testCopyDir(t, testFixturePath("init-get-provider-detected-duplicate"), td)
+	defer testChdir(t, td)()
+
+	// We need to construct a multisource with a mock source and a registry
+	// source: the mock source will return ErrRegistryProviderNotKnown for an
+	// unknown provider, and the registry source will allow us to look up the
+	// appropriate namespace if possible.
+	providerSource, psClose := newMockProviderSource(t, map[string][]string{
+		"hashicorp/foo": {"1.2.3"},
+		"opentofu/foo":  {"1.2.3"},
+		"hashicorp/bar": {"1.2.3"},
+	})
+	defer psClose()
+	registrySource, rsClose := testRegistrySource(t)
+	defer rsClose()
+	multiSource := getproviders.MultiSource{
+		{Source: providerSource},
+		{Source: registrySource},
+	}
+
+	ui := new(cli.MockUi)
+	view, _ := testView(t)
+	m := Meta{
+		Ui:             ui,
+		View:           view,
+		ProviderSource: multiSource,
+	}
+
+	c := &InitCommand{
+		Meta: m,
+	}
+
+	args := []string{
+		"-backend=false", // should be possible to install plugins without backend init
+	}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("expected error, got output: \n%s\n%s", ui.OutputWriter.String(), ui.ErrorWriter.String())
+	}
+
+	// error output is the main focus of this test
+	errOutput := ui.ErrorWriter.String()
+	errors := []string{
+		"Warning: Potential provider misconfiguration",
+		"OpenTofu has detected multiple providers of type foo",
+		"If this is intentional you can ignore this warning",
+	}
+	unexpected := []string{
+		"OpenTofu has detected multiple providers of type bar",
+	}
+	for _, want := range errors {
+		if !strings.Contains(errOutput, want) {
+			t.Fatalf("expected error %q: %s", want, errOutput)
+		}
+	}
+	for _, unwanted := range unexpected {
+		if strings.Contains(errOutput, unwanted) {
+			t.Fatalf("unexpected error %q: %s", unwanted, errOutput)
+		}
+	}
+
+}
+
 func TestInit_providerSource(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := t.TempDir()

internal/command/testdata/init-get-provider-detected-duplicate/child/main.tf

@@ -0,0 +1,10 @@
+terraform {
+	required_providers {
+		dupechild = {
+			source = "hashicorp/bar"
+		}
+	}
+}
+
+// This will try to install hashicorp/foo
+provider foo {}

internal/command/testdata/init-get-provider-detected-duplicate/main.tf

@@ -0,0 +1,15 @@
+terraform {
+	required_providers {
+		foo = {
+			// This will conflict with the child modules hashicorp/foo
+			source = "opentofu/foo"
+		}
+		dupe = {
+			// This should not conflict with the child modules hashicorp/bar
+			source = "bar"
+		}
+	}
+}
+module "some-baz-stuff" {
+  source = "./child"
+}