Warn if project.toml contains keys not supported by schema

acceptance/acceptance_test.go

@@ -2346,6 +2346,114 @@ include = [ "*.jar", "media/mountain.jpg", "/media/person.png", ]
 							})
 						})
 					})
+
+					when("unsupported keys for schema are present in project.toml", func() {
+						var tempAppDir string
+
+						it.Before(func() {
+							appPath := filepath.Join("testdata", "mock_app")
+
+							var err error
+							tempAppDir, err = os.MkdirTemp("", "unsupported-schema-keys-app")
+							assert.Nil(err)
+
+							h.RecursiveCopy(t, appPath, tempAppDir)
+						})
+
+						it.After(func() {
+							os.RemoveAll(tempAppDir)
+						})
+
+						it("reports unsupported keys with default schema", func() {
+							h.SkipIf(t, !pack.SupportsFeature(invoke.UnsupportedSchemaKeysWarning), "")
+
+							projectToml := `
+[project]
+  version = "1.0.2"
+  source-url = "https://github.com/buildpacks/pack"
+
+[unsupported-table]
+  unsupported-key = "some value"
+`
+							err := os.WriteFile(filepath.Join(tempAppDir, "project.toml"), []byte(projectToml), 0755)
+							assert.Nil(err)
+
+							output := pack.RunSuccessfully(
+								"build", repoName,
+								"-p", tempAppDir,
+							)
+
+							assert.Contains(output, "No schema version declared in project.toml, defaulting to schema version 0.1")
+
+							assertOutput := assertions.NewOutputAssertionManager(t, output)
+							assertOutput.ReportsUnsupportedKeys("0.1")
+							assertOutput.ReportsSuccessfulImageBuild(repoName)
+
+							t.Log("app is runnable")
+							assertImage.RunsWithOutput(repoName, "Launch Dep Contents", "Cached Dep Contents")
+						})
+
+						it("reports unsupported keys with schema version 0.1", func() {
+							h.SkipIf(t, !pack.SupportsFeature(invoke.UnsupportedSchemaKeysWarning), "")
+
+							projectToml := `
+[_]
+  schema-version = "0.1"
+
+[project]
+  version = "1.0.2"
+  source-url = "https://github.com/buildpacks/pack"
+
+[unsupported-table]
+  unsupported-key = "some value"
+`
+							err := os.WriteFile(filepath.Join(tempAppDir, "project.toml"), []byte(projectToml), 0755)
+							assert.Nil(err)
+
+							output := pack.RunSuccessfully(
+								"build", repoName,
+								"-p", tempAppDir,
+							)
+
+							assert.NotContains(output, "No schema version declared in project.toml, defaulting to schema version 0.1")
+
+							assertOutput := assertions.NewOutputAssertionManager(t, output)
+							assertOutput.ReportsUnsupportedKeys("0.1")
+							assertOutput.ReportsSuccessfulImageBuild(repoName)
+
+							t.Log("app is runnable")
+							assertImage.RunsWithOutput(repoName, "Launch Dep Contents", "Cached Dep Contents")
+						})
+
+						it("reports unsupported keys with schema version 0.2", func() {
+							h.SkipIf(t, !pack.SupportsFeature(invoke.UnsupportedSchemaKeysWarning), "")
+
+							projectToml := `
+[_]
+  schema-version = "0.2"
+  name = "project name"
+
+[unsupported-table]
+  unsupported-key = "some value"
+`
+							err := os.WriteFile(filepath.Join(tempAppDir, "project.toml"), []byte(projectToml), 0755)
+							assert.Nil(err)
+
+							output := pack.RunSuccessfully(
+								"build", repoName,
+								"-p", tempAppDir,
+							)
+
+							assert.NotContains(output, "No schema version declared in project.toml, defaulting to schema version 0.1")
+
+							assertOutput := assertions.NewOutputAssertionManager(t, output)
+							assertOutput.ReportsUnsupportedKeys("0.2")
+							assertOutput.ReportsSuccessfulImageBuild(repoName)
+
+							t.Log("app is runnable")
+							assertImage.RunsWithOutput(repoName, "Launch Dep Contents", "Cached Dep Contents")
+						})
+					})
 				})
 
 				when("build --buildpack <flattened buildpack>", func() {

acceptance/assertions/output.go

@@ -243,3 +243,9 @@ func (o OutputAssertionManager) ReportsInvalidBuilderToml() {
 
 	o.assert.Contains(o.output, "invalid builder toml")
 }
+
+func (o OutputAssertionManager) ReportsUnsupportedKeys(schemaVersion string) {
+	o.testObject.Helper()
+
+	o.assert.ContainsF(o.output, "Warning: The following keys declared in project.toml are not supported in schema version %s:\n- unsupported-table\n- unsupported-table.unsupported-key\nThe above keys will be ignored. If this is not intentional, maybe try updating your schema version.\n", schemaVersion)
+}

acceptance/invoke/pack.go

@@ -236,6 +236,7 @@ const (
 	BuildpackFlatten
 	MetaBuildpackFolder
 	PlatformRetries
+	UnsupportedSchemaKeysWarning
 	FlattenBuilderCreationV2
 )
 
@@ -267,6 +268,9 @@ var featureTests = map[Feature]func(i *PackInvoker) bool{
 	PlatformRetries: func(i *PackInvoker) bool {
 		return i.atLeast("v0.32.1")
 	},
+	UnsupportedSchemaKeysWarning: func(i *PackInvoker) bool {
+		return i.atLeast("v0.33.0")
+  	},
 	FlattenBuilderCreationV2: func(i *PackInvoker) bool {
 		return i.atLeast("v0.33.1")
 	},

pkg/project/project.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/BurntSushi/toml"
 	"github.com/pkg/errors"
@@ -21,7 +22,7 @@ type VersionDescriptor struct {
 	Project Project `toml:"_"`
 }
 
-var parsers = map[string]func(string) (types.Descriptor, error){
+var parsers = map[string]func(string) (types.Descriptor, toml.MetaData, error){
 	"0.1": v01.NewDescriptor,
 	"0.2": v02.NewDescriptor,
 }
@@ -45,21 +46,44 @@ func ReadProjectDescriptor(pathToFile string) (types.Descriptor, error) {
 
 	version := versionDescriptor.Project.Version
 	if version == "" {
+		fmt.Println("No schema version declared in project.toml, defaulting to schema version 0.1")
 		version = "0.1"
 	}
 
 	if _, ok := parsers[version]; !ok {
 		return types.Descriptor{}, fmt.Errorf("unknown project descriptor schema version %s", version)
 	}
 
-	descriptor, err := parsers[version](string(projectTomlContents))
+	descriptor, tomlMetaData, err := parsers[version](string(projectTomlContents))
 	if err != nil {
 		return types.Descriptor{}, err
 	}
 
+	warnIfTomlContainsKeysNotSupportedBySchema(version, tomlMetaData)
+
 	return descriptor, validate(descriptor)
 }
 
+func warnIfTomlContainsKeysNotSupportedBySchema(schemaVersion string, tomlMetaData toml.MetaData) {
+	unsupportedKeys := []string{}
+
+	// filter out any keys from [_]
+	for _, undecodedKey := range tomlMetaData.Undecoded() {
+		keyName := undecodedKey.String()
+		if keyName != "_" && !strings.HasPrefix(keyName, "_.schema-version") {
+			unsupportedKeys = append(unsupportedKeys, keyName)
+		}
+	}
+
+	if len(unsupportedKeys) != 0 {
+		fmt.Printf("Warning: The following keys declared in project.toml are not supported in schema version %s:\n", schemaVersion)
+		for _, unsupportedKey := range unsupportedKeys {
+			fmt.Printf("- %s\n", unsupportedKey)
+		}
+		fmt.Printf("The above keys will be ignored. If this is not intentional, maybe try updating your schema version.\n")
+	}
+}
+
 func validate(p types.Descriptor) error {
 	if p.Build.Exclude != nil && p.Build.Include != nil {
 		return errors.New("project.toml: cannot have both include and exclude defined")

pkg/project/project_test.go

@@ -374,6 +374,44 @@ name = "licenses should have either a type or uri defined"
 				t.Fatal("Expected error for having neither type or uri defined for licenses")
 			}
 		})
+
+		it("should allow for unsupported keys to be declared with schema v0.1", func() {
+			projectToml := `
+[_]
+schema-version = "0.1"
+
+[unsupported-table]
+unsupported-key = "some value"
+`
+			tmpProjectToml, err := createTmpProjectTomlFile(projectToml)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			_, err = ReadProjectDescriptor(tmpProjectToml.Name())
+			if err != nil {
+				t.Fatal("Expected unsupported keys in schema v0.1 to not throw an error")
+			}
+		})
+
+		it("should allow for unsupported keys to be declared with schema v0.2", func() {
+			projectToml := `
+[_]
+schema-version = "0.2"
+
+[unsupported-table]
+unsupported-key = "some value"
+`
+			tmpProjectToml, err := createTmpProjectTomlFile(projectToml)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			_, err = ReadProjectDescriptor(tmpProjectToml.Name())
+			if err != nil {
+				t.Fatal("Expected unsupported keys in schema v0.2 to not throw an error")
+			}
+		})
 	})
 }
 

pkg/project/v01/project.go

@@ -13,18 +13,18 @@ type Descriptor struct {
 	Metadata map[string]interface{} `toml:"metadata"`
 }
 
-func NewDescriptor(projectTomlContents string) (types.Descriptor, error) {
+func NewDescriptor(projectTomlContents string) (types.Descriptor, toml.MetaData, error) {
 	versionedDescriptor := &Descriptor{}
 
-	_, err := toml.Decode(projectTomlContents, versionedDescriptor)
+	tomlMetaData, err := toml.Decode(projectTomlContents, versionedDescriptor)
 	if err != nil {
-		return types.Descriptor{}, err
+		return types.Descriptor{}, tomlMetaData, err
 	}
 
 	return types.Descriptor{
 		Project:       versionedDescriptor.Project,
 		Build:         versionedDescriptor.Build,
 		Metadata:      versionedDescriptor.Metadata,
 		SchemaVersion: api.MustParse("0.1"),
-	}, nil
+	}, tomlMetaData, nil
 }

pkg/project/v02/project.go

@@ -43,11 +43,11 @@ type Descriptor struct {
 	IO      IO      `toml:"io"`
 }
 
-func NewDescriptor(projectTomlContents string) (types.Descriptor, error) {
+func NewDescriptor(projectTomlContents string) (types.Descriptor, toml.MetaData, error) {
 	versionedDescriptor := &Descriptor{}
-	_, err := toml.Decode(projectTomlContents, &versionedDescriptor)
+	tomlMetaData, err := toml.Decode(projectTomlContents, &versionedDescriptor)
 	if err != nil {
-		return types.Descriptor{}, err
+		return types.Descriptor{}, tomlMetaData, err
 	}
 
 	// backward compatibility for incorrect key
@@ -72,5 +72,5 @@ func NewDescriptor(projectTomlContents string) (types.Descriptor, error) {
 		},
 		Metadata:      versionedDescriptor.Project.Metadata,
 		SchemaVersion: api.MustParse("0.2"),
-	}, nil
+	}, tomlMetaData, nil
 }