cliconfig+main: Allow oci_mirror as a new provider installation method

It's now valid to include an oci_mirror block in the provider_installation
block in the CLI configuration, specifying that OpenTofu should try to
install providers from OCI repositories based on a template that maps
from OpenTofu-style provider source addresses into OCI repository
addresses.

The getproviders.Source implementation for this was added in a previous
commit, so this is mainly just wiring it up to the cliconfig layer and
the dependency wiring code in package main.

Signed-off-by: Martin Atkins <mart@degeneration.co.uk>

internal/command/cliconfig/provider_installation_test.go

@@ -7,9 +7,11 @@ package cliconfig
 
 import (
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	svchost "github.com/hashicorp/terraform-svchost"
 	"github.com/opentofu/opentofu/internal/addrs"
 	"github.com/opentofu/opentofu/internal/getproviders"
 )
@@ -80,3 +82,196 @@ func TestLoadConfig_providerInstallationErrors(t *testing.T) {
 		t.Errorf("wrong diagnostics\ngot:\n%s\nwant:\n%s", got, want)
 	}
 }
+
+func TestLoadConfig_providerInstallationOCIMirror(t *testing.T) {
+	for _, configFile := range []string{"provider-installation-oci", "provider-installation-oci.json"} {
+		t.Run(configFile, func(t *testing.T) {
+			gotConfig, diags := loadConfigFile(filepath.Join(fixtureDir, configFile))
+			if diags.HasErrors() {
+				t.Fatalf("unexpected diagnostics: %s", diags.Err().Error())
+			}
+
+			gotInstBlocks := gotConfig.ProviderInstallation
+			if got, want := len(gotInstBlocks), 1; got != want {
+				t.Fatalf("wrong number of provider_installation blocks %d; want %d", got, want)
+			}
+			gotMethods := gotInstBlocks[0].Methods
+			if got, want := len(gotMethods), 4; got != want {
+				t.Fatalf("wrong number of provider installation methods %d; want %d", got, want)
+			}
+
+			providerAddr := addrs.Provider{
+				Hostname:  svchost.Hostname("registry.opentofu.org"),
+				Namespace: "opentofu",
+				Type:      "foo",
+			}
+			t.Run("all segments in template", func(t *testing.T) {
+				method := gotMethods[0]
+				loc, ok := method.Location.(ProviderInstallationOCIMirror)
+				if !ok {
+					t.Fatalf("wrong location type %T; want %T", method.Location, loc)
+				}
+				gotRegistry, gotRepository, err := loc.RepositoryMapping(providerAddr)
+				if err != nil {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if got, want := gotRegistry, "example.com"; got != want {
+					t.Errorf("wrong registry domain %q; want %q", got, want)
+				}
+				if got, want := gotRepository, "registry.opentofu.org/opentofu/foo"; got != want {
+					t.Errorf("wrong repository name %q; want %q", got, want)
+				}
+			})
+			t.Run("hostname chosen by include", func(t *testing.T) {
+				method := gotMethods[1]
+				loc, ok := method.Location.(ProviderInstallationOCIMirror)
+				if !ok {
+					t.Fatalf("wrong location type %T; want %T", method.Location, loc)
+				}
+				gotRegistry, gotRepository, err := loc.RepositoryMapping(providerAddr)
+				if err != nil {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if got, want := gotRegistry, "example.net"; got != want {
+					t.Errorf("wrong registry domain %q; want %q", got, want)
+				}
+				if got, want := gotRepository, "opentofu-registry/opentofu/foo"; got != want {
+					t.Errorf("wrong repository name %q; want %q", got, want)
+				}
+			})
+			t.Run("hostname and namespace chosen by include", func(t *testing.T) {
+				method := gotMethods[2]
+				loc, ok := method.Location.(ProviderInstallationOCIMirror)
+				if !ok {
+					t.Fatalf("wrong location type %T; want %T", method.Location, loc)
+				}
+				gotRegistry, gotRepository, err := loc.RepositoryMapping(providerAddr)
+				if err != nil {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if got, want := gotRegistry, "example.net"; got != want {
+					t.Errorf("wrong registry domain %q; want %q", got, want)
+				}
+				if got, want := gotRepository, "opentofu-registry/opentofu-namespace/foo"; got != want {
+					t.Errorf("wrong repository name %q; want %q", got, want)
+				}
+			})
+			t.Run("all components chosen by include", func(t *testing.T) {
+				method := gotMethods[3]
+				loc, ok := method.Location.(ProviderInstallationOCIMirror)
+				if !ok {
+					t.Fatalf("wrong location type %T; want %T", method.Location, loc)
+				}
+				gotRegistry, gotRepository, err := loc.RepositoryMapping(providerAddr)
+				if err != nil {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if got, want := gotRegistry, "example.net"; got != want {
+					t.Errorf("wrong registry domain %q; want %q", got, want)
+				}
+				if got, want := gotRepository, "opentofu-registry/opentofu-namespace/foo-type"; got != want {
+					t.Errorf("wrong repository name %q; want %q", got, want)
+				}
+			})
+		})
+	}
+}
+
+func TestLoadConfig_providerInstallationOCIMirrorErrors(t *testing.T) {
+	t.Run("missing hostname reference", func(t *testing.T) {
+		_, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-missinghostname"))
+		if !diags.HasErrors() {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := diags.Err().Error(), `template must refer to the "hostname" symbol`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("missing namespace reference", func(t *testing.T) {
+		_, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-missingnamespace"))
+		if !diags.HasErrors() {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := diags.Err().Error(), `template must refer to the "namespace" symbol`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("missing type reference", func(t *testing.T) {
+		_, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-missingtype"))
+		if !diags.HasErrors() {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := diags.Err().Error(), `template must refer to the "type" symbol`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("type error in template", func(t *testing.T) {
+		_, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-typeerror"))
+		if !diags.HasErrors() {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := diags.Err().Error(), `This value does not have any indices`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("value error in template", func(t *testing.T) {
+		_, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-valueerror"))
+		if !diags.HasErrors() {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := diags.Err().Error(), `a number is required`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("dynamic error in template", func(t *testing.T) {
+		cfg, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-dynerror"))
+		if diags.HasErrors() {
+			t.Fatalf("unexpected error for configuration load (error should be only during template evaluation)")
+		}
+		method, ok := cfg.ProviderInstallation[0].Methods[0].Location.(ProviderInstallationOCIMirror)
+		if !ok {
+			t.Fatalf("wrong installation method location type")
+		}
+		_, _, err := method.RepositoryMapping(addrs.Provider{
+			Hostname:  svchost.Hostname("example.net"), // This template fails for anything other than "example.com"
+			Namespace: "whatever",
+			Type:      "anything",
+		})
+		if err == nil {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := err.Error(), `The given key does not identify an element in this collection value`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+	t.Run("unmappable characters in provider source address", func(t *testing.T) {
+		// This deals with a particularly-annoying case: OpenTofu provider source addresses
+		// support a wide range of unicode characters with the intent that folks can name
+		// their private providers using the alphabet of their native language, but OCI Distribution
+		// only allows ASCII characters in repository names, so for now the OCI mirror
+		// installation method can only work with providers whose namespace and type
+		// are ASCII-only. Non-ASCII characters are pretty rare in practice for public
+		// providers, but we can't tell whether they are more common in private provider
+		// registries. For now we treat this as an error but we might try to find a better
+		// answer for this in a future release if it proves to be a problem in practice.
+		cfg, diags := loadConfigFile(filepath.Join(fixtureDir, "provider-installation-oci-passthru"))
+		if diags.HasErrors() {
+			t.Fatalf("unexpected error for configuration load (error should be only during template evaluation)")
+		}
+		method, ok := cfg.ProviderInstallation[0].Methods[0].Location.(ProviderInstallationOCIMirror)
+		if !ok {
+			t.Fatalf("wrong installation method location type")
+		}
+		_, _, err := method.RepositoryMapping(addrs.Provider{
+			Hostname:  svchost.Hostname("example.com"),
+			Namespace: "ほげ",
+			Type:      "ふが",
+		})
+		if err == nil {
+			t.Fatalf("unexpected success; want error")
+		}
+		if got, want := err.Error(), `invalid repository "example.com/ほげ/ふが"`; !strings.Contains(got, want) {
+			t.Errorf("missing expected error\ngot: %s\nwant substring: %s", got, want)
+		}
+	})
+}