Use the apparentlymart/go-versions library to parse module constraints (

#32377)

* Use the apparentlymart/go-versions library to parse module constraints

* goimports

* Update comments, and parse versions carefully

* add acceptance tests to verify behaviour of partial matches

* goimports

internal/initwd/module_install.go

@@ -10,7 +10,9 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/apparentlymart/go-versions/versions"
 	version "github.com/hashicorp/go-version"
+
 	"github.com/hashicorp/terraform-config-inspect/tfconfig"
 	"github.com/hashicorp/terraform/internal/addrs"
 	"github.com/hashicorp/terraform/internal/earlyconfig"
@@ -387,9 +389,45 @@ func (i *ModuleInstaller) installRegistryModule(ctx context.Context, req *earlyc
 
 		// If we've found a pre-release version then we'll ignore it unless
 		// it was exactly requested.
-		if v.Prerelease() != "" && req.VersionConstraints.String() != v.String() {
-			log.Printf("[TRACE] ModuleInstaller: %s ignoring %s because it is a pre-release and was not requested exactly", key, v)
-			continue
+		//
+		// The prerelease checking will be handled by a different library for
+		// 2 reasons. First, this other library automatically includes the
+		// "prerelease versions must be exactly requested" behaviour that we are
+		// looking for. Second, this other library is used to handle all version
+		// constraints for the provider logic and this is the first step to
+		// making the module and provider version logic match.
+		if v.Prerelease() != "" {
+			// At this point all versions published by the module with
+			// prerelease metadata will be checked. Users may not have even
+			// requested this prerelease so don't print lots of unnecessary #
+			// warnings.
+			acceptableVersions, err := versions.MeetingConstraintsString(req.VersionConstraints.String())
+			if err != nil {
+				log.Printf("[WARN] ModuleInstaller: %s ignoring %s because the version constraints (%s) could not be parsed: %s", key, v, req.VersionConstraints.String(), err.Error())
+				continue
+			}
+
+			// Validate the version is also readable by the other versions
+			// library.
+			version, err := versions.ParseVersion(v.String())
+			if err != nil {
+				log.Printf("[WARN] ModuleInstaller: %s ignoring %s because the version (%s) reported by the module could not be parsed: %s", key, v, v.String(), err.Error())
+				continue
+			}
+
+			// Finally, check if the prerelease is acceptable to version. As
+			// highlighted previously, we go through all of this because the
+			// apparentlymart/go-versions library handles prerelease constraints
+			// in the apporach we want to.
+			if !acceptableVersions.Has(version) {
+				log.Printf("[TRACE] ModuleInstaller: %s ignoring %s because it is a pre-release and was not requested exactly", key, v)
+				continue
+			}
+
+			// If we reach here, it means this prerelease version was exactly
+			// requested according to the extra constraints of this library.
+			// We fall through and allow the other library to also validate it
+			// for consistency.
 		}
 
 		if latestVersion == nil || v.GreaterThan(latestVersion) {

internal/initwd/module_install_test.go

@@ -178,6 +178,54 @@ func TestModuleInstaller_explicitPackageBoundary(t *testing.T) {
 	}
 }
 
+func TestModuleInstaller_ExactMatchPrerelease(t *testing.T) {
+	if os.Getenv("TF_ACC") == "" {
+		t.Skip("this test accesses registry.terraform.io and github.com; set TF_ACC=1 to run it")
+	}
+
+	fixtureDir := filepath.Clean("testdata/prerelease-version-constraint-match")
+	dir, done := tempChdir(t, fixtureDir)
+	defer done()
+
+	hooks := &testInstallHooks{}
+
+	modulesDir := filepath.Join(dir, ".terraform/modules")
+	inst := NewModuleInstaller(modulesDir, registry.NewClient(nil, nil))
+	cfg, diags := inst.InstallModules(context.Background(), ".", false, hooks)
+
+	if diags.HasErrors() {
+		t.Fatalf("found unexpected errors: %s", diags.Err())
+	}
+
+	if !cfg.Children["acctest_exact"].Version.Equal(version.Must(version.NewVersion("v0.0.3-alpha.1"))) {
+		t.Fatalf("expected version %s but found version %s", "v0.0.3-alpha.1", cfg.Version.String())
+	}
+}
+
+func TestModuleInstaller_PartialMatchPrerelease(t *testing.T) {
+	if os.Getenv("TF_ACC") == "" {
+		t.Skip("this test accesses registry.terraform.io and github.com; set TF_ACC=1 to run it")
+	}
+
+	fixtureDir := filepath.Clean("testdata/prerelease-version-constraint")
+	dir, done := tempChdir(t, fixtureDir)
+	defer done()
+
+	hooks := &testInstallHooks{}
+
+	modulesDir := filepath.Join(dir, ".terraform/modules")
+	inst := NewModuleInstaller(modulesDir, registry.NewClient(nil, nil))
+	cfg, diags := inst.InstallModules(context.Background(), ".", false, hooks)
+
+	if diags.HasErrors() {
+		t.Fatalf("found unexpected errors: %s", diags.Err())
+	}
+
+	if !cfg.Children["acctest_partial"].Version.Equal(version.Must(version.NewVersion("v0.0.2"))) {
+		t.Fatalf("expected version %s but found version %s", "v0.0.2", cfg.Version.String())
+	}
+}
+
 func TestModuleInstaller_invalid_version_constraint_error(t *testing.T) {
 	fixtureDir := filepath.Clean("testdata/invalid-version-constraint")
 	dir, done := tempChdir(t, fixtureDir)

internal/initwd/testdata/prerelease-version-constraint-match/root.tf

@@ -0,0 +1,7 @@
+# We expect this test to download the requested version because it is an exact
+# match for a prerelease version.
+
+module "acctest_exact" {
+  source = "hashicorp/module-installer-acctest/aws"
+  version = "=0.0.3-alpha.1"
+}

internal/initwd/testdata/prerelease-version-constraint/root.tf

@@ -0,0 +1,8 @@
+# We expect this test to download the version 0.0.2, the one before the
+# specified version even with the equality because the specified version is a
+# prerelease.
+
+module "acctest_partial" {
+  source = "hashicorp/module-installer-acctest/aws"
+  version = "<=0.0.3-alpha.1"
+}