[codegen/schema] Add a schema checker (#7865)

- Change the schema package to report semantic errors as diagnostics
  rather than Go errors
- Add a `pulumi schema check` command to the CLI for static checking of
  package schemas

The semantic checker can be extended in the future to add support for
target-specific checks.

CHANGELOG_PENDING.md

@@ -10,4 +10,7 @@
   making it easier to compose functions/datasources with Pulumi
   resources. [#7784](https://github.com/pulumi/pulumi/pull/7784)
 
+- [codegen/schema] Add a `pulumi schema check` command to validate package schemas.
+  [#7865](https://github.com/pulumi/pulumi/pull/7865)
+
 ### Bug Fixes

pkg/cmd/pulumi/pulumi.go

@@ -208,6 +208,7 @@ func NewPulumiCmd() *cobra.Command {
 	cmd.AddCommand(newPluginCmd())
 	cmd.AddCommand(newVersionCmd())
 	cmd.AddCommand(newConsoleCmd())
+	cmd.AddCommand(newSchemaCmd())
 
 	// Less common, and thus hidden, commands:
 	cmd.AddCommand(newGenCompletionCmd(cmd))

pkg/cmd/pulumi/schema.go

@@ -0,0 +1,35 @@
+// Copyright 2016-2021, Pulumi Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"github.com/pulumi/pulumi/sdk/v3/go/common/util/cmdutil"
+	"github.com/spf13/cobra"
+)
+
+func newSchemaCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "schema",
+		Short: "Analyze package schemas",
+		Long: `Analyze package schemas
+
+Subcommands of this command can be used to analyze Pulumi package schemas. This can be useful to check hand-authored
+package schemas for errors.`,
+		Args: cmdutil.NoArgs,
+	}
+
+	cmd.AddCommand(newSchemaCheckCommand())
+	return cmd
+}

pkg/cmd/pulumi/schema_check.go

@@ -0,0 +1,79 @@
+// Copyright 2016-2021, Pulumi Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/hashicorp/hcl/v2"
+	"github.com/spf13/cobra"
+	"gopkg.in/yaml.v3"
+
+	"github.com/pulumi/pulumi/pkg/v3/codegen/schema"
+	"github.com/pulumi/pulumi/sdk/v3/go/common/util/cmdutil"
+	"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
+)
+
+func newSchemaCheckCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "check",
+		Args:  cmdutil.ExactArgs(1),
+		Short: "Check a Pulumi package schema for errors",
+		Long: "Check a Pulumi package schema for errors.\n" +
+			"\n" +
+			"Ensure that a Pulumi package schema meets the requirements imposed by the\n" +
+			"schema spec as well as additional requirements imposed by the supported\n" +
+			"target languages.",
+		Run: cmdutil.RunFunc(func(cmd *cobra.Command, args []string) error {
+			file := args[0]
+
+			// Read from stdin or a specified file
+			reader := os.Stdin
+			if file != "-" {
+				f, err := os.Open(file)
+				if err != nil {
+					return fmt.Errorf("could not open file %v: %w", file, err)
+				}
+				reader = f
+			}
+			schemaBytes, err := ioutil.ReadAll(reader)
+			if err != nil {
+				return fmt.Errorf("failed to read schema: %w", err)
+			}
+
+			var pkgSpec schema.PackageSpec
+			if ext := filepath.Ext(file); ext == ".yaml" || ext == ".yml" {
+				err = yaml.Unmarshal(schemaBytes, &pkgSpec)
+			} else {
+				err = json.Unmarshal(schemaBytes, &pkgSpec)
+			}
+			if err != nil {
+				return fmt.Errorf("failed to unmarshal schema: %w", err)
+			}
+
+			_, diags, err := schema.BindSpec(pkgSpec, nil)
+			diagWriter := hcl.NewDiagnosticTextWriter(os.Stderr, nil, 0, true)
+			wrErr := diagWriter.WriteDiagnostics(diags)
+			contract.IgnoreError(wrErr)
+			return err
+		}),
+	}
+
+	return cmd
+}

pkg/codegen/schema/loader.go

@@ -94,10 +94,13 @@ func (l *pluginLoader) LoadPackage(pkg string, version *semver.Version) (*Packag
 		return nil, err
 	}
 
-	p, err := importSpec(spec, nil, l)
+	p, diags, err := bindSpec(spec, nil, l)
 	if err != nil {
 		return nil, err
 	}
+	if diags.HasErrors() {
+		return nil, diags
+	}
 
 	l.m.Lock()
 	defer l.m.Unlock()

pkg/codegen/schema/schema_test.go

@@ -324,9 +324,9 @@ func Test_parseTypeSpecRef(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := typs.parseTypeSpecRef(tt.ref)
-			if (err != nil) != tt.wantErr {
-				t.Errorf("parseTypeSpecRef() error = %v, wantErr %v", err, tt.wantErr)
+			got, diags := typs.parseTypeSpecRef("ref", tt.ref)
+			if diags.HasErrors() != tt.wantErr {
+				t.Errorf("parseTypeSpecRef() diags = %v, wantErr %v", diags, tt.wantErr)
 				return
 			}
 			if !reflect.DeepEqual(got, tt.want) {
@@ -370,27 +370,27 @@ func TestMethods(t *testing.T) {
 		},
 		{
 			filename:      "bad-methods-1.json",
-			expectedError: "unknown function xyz:index:Foo/bar for method bar",
+			expectedError: "unknown function xyz:index:Foo/bar",
 		},
 		{
 			filename:      "bad-methods-2.json",
-			expectedError: "function xyz:index:Foo/bar for method baz is already a method",
+			expectedError: "function xyz:index:Foo/bar is already a method",
 		},
 		{
 			filename:      "bad-methods-3.json",
-			expectedError: "invalid function token format xyz:index:Foo for method bar",
+			expectedError: "invalid function token format xyz:index:Foo",
 		},
 		{
 			filename:      "bad-methods-4.json",
-			expectedError: "invalid function token format xyz:index:Baz/bar for method bar",
+			expectedError: "invalid function token format xyz:index:Baz/bar",
 		},
 		{
 			filename:      "bad-methods-5.json",
-			expectedError: "function xyz:index:Foo/bar for method bar is missing __self__ parameter",
+			expectedError: "function xyz:index:Foo/bar has no __self__ parameter",
 		},
 		{
 			filename:      "bad-methods-6.json",
-			expectedError: "property and method have the same name bar",
+			expectedError: "xyz:index:Foo already has a property named bar",
 		},
 	}
 	for _, tt := range tests {