feat(render): add new command to render final file

CHANGELOG.md

@@ -65,6 +65,14 @@
 
 > Release date: TBD
 
+### Added
+
+- Added a new command `file render` to render a final decK file. This will result in a file representing
+  the state as it would be synced online.
+  [#963](https://github.com/Kong/deck/pull/963)
+- Added a new flag `--format` to `file convert` to enable JSON output.
+  [#963](https://github.com/Kong/deck/pull/963)
+
 ### Fixes
 
 - Avoid misleading diffs when configuration file has empty tags.

cmd/common.go

@@ -104,7 +104,7 @@ func syncMain(ctx context.Context, filenames []string, dry bool, parallelism,
 			Deleting: []diff.EntityState{},
 		}
 	}
-	targetContent, err := file.GetContentFromFiles(filenames)
+	targetContent, err := file.GetContentFromFiles(filenames, false)
 	if err != nil {
 		return err
 	}

cmd/common_konnect.go

@@ -183,7 +183,7 @@ func syncKonnect(ctx context.Context,
 	httpClient := utils.HTTPClient()
 
 	// read target file
-	targetContent, err := file.GetContentFromFiles(filenames)
+	targetContent, err := file.GetContentFromFiles(filenames, false)
 	if err != nil {
 		return err
 	}

cmd/file.go

@@ -1,18 +1,9 @@
-/*
-Copyright © 2023 NAME HERE <EMAIL ADDRESS>
-*/
 package cmd
 
 import (
 	"github.com/spf13/cobra"
 )
 
-//
-//
-// Define the CLI data for the file sub-command
-//
-//
-
 func newAddFileCmd() *cobra.Command {
 	addFileCmd := &cobra.Command{
 		Use:   "file [sub-command]...",

cmd/convert.go → cmd/file_convert.go

@@ -3,19 +3,22 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/kong/deck/convert"
 	"github.com/kong/deck/cprint"
+	"github.com/kong/deck/file"
 	"github.com/kong/deck/utils"
 	"github.com/spf13/cobra"
 )
 
 var (
 	convertCmdSourceFormat      string
-	convertCmdDestinationFormat string
+	convertCmdDestinationFormat string // konnect/kong-gateway-3.x/etc
 	convertCmdInputFile         string
 	convertCmdOutputFile        string
 	convertCmdAssumeYes         bool
+	convertCmdStateFormat       string // yaml/json output
 )
 
 func executeConvert(_ *cobra.Command, _ []string) error {
@@ -37,7 +40,13 @@ func executeConvert(_ *cobra.Command, _ []string) error {
 			return nil
 		}
 
-		err = convert.Convert(convertCmdInputFile, convertCmdOutputFile, sourceFormat, destinationFormat)
+		err = convert.Convert(
+			[]string{convertCmdInputFile},
+			convertCmdOutputFile,
+			file.Format(strings.ToUpper(convertCmdStateFormat)),
+			sourceFormat,
+			destinationFormat,
+			false)
 		if err != nil {
 			return fmt.Errorf("converting file: %w", err)
 		}
@@ -51,7 +60,13 @@ func executeConvert(_ *cobra.Command, _ []string) error {
 			return fmt.Errorf("getting files from directory: %w", err)
 		}
 		for _, filename := range files {
-			err = convert.Convert(filename, filename, sourceFormat, destinationFormat)
+			err = convert.Convert(
+				[]string{filename},
+				filename,
+				file.Format(strings.ToUpper(convertCmdStateFormat)),
+				sourceFormat,
+				destinationFormat,
+				false)
 			if err != nil {
 				return fmt.Errorf("converting '%s' file: %w", filename, err)
 			}
@@ -92,6 +107,9 @@ can be converted into a 'kong-gateway-3.x' configuration file.`,
 		"file to write configuration to after conversion. Use `-` to write to stdout.")
 	convertCmd.Flags().BoolVar(&convertCmdAssumeYes, "yes",
 		false, "assume `yes` to prompts and run non-interactively.")
+	convertCmd.Flags().StringVar(&convertCmdStateFormat, "format",
+		"yaml", "output file format: json or yaml.")
+
 	return convertCmd
 }
 

cmd/file_render.go

@@ -0,0 +1,50 @@
+package cmd
+
+import (
+	"strings"
+
+	"github.com/kong/deck/convert"
+	"github.com/kong/deck/file"
+	"github.com/spf13/cobra"
+)
+
+var (
+	fileRenderCmdKongStateFile  []string
+	fileRenderCmdKongFileOutput string
+	fileRenderCmdStateFormat    string
+)
+
+func executeFileRenderCmd(_ *cobra.Command, _ []string) error {
+	return convert.Convert(
+		fileRenderCmdKongStateFile,
+		fileRenderCmdKongFileOutput,
+		file.Format(strings.ToUpper(fileRenderCmdStateFormat)),
+		convert.FormatDistributed,
+		convert.FormatKongGateway3x,
+		true)
+}
+
+func newFileRenderCmd() *cobra.Command {
+	renderCmd := &cobra.Command{
+		Use:   "render",
+		Short: "Render the configuration as Kong declarative config",
+		Long:  ``,
+		Args:  cobra.ArbitraryArgs,
+		RunE:  executeFileRenderCmd,
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			fileRenderCmdKongStateFile = args
+			if len(fileRenderCmdKongStateFile) == 0 {
+				fileRenderCmdKongStateFile = []string{"-"} // default to stdin
+			}
+			return preRunSilenceEventsFlag()
+		},
+	}
+
+	renderCmd.Flags().StringVarP(&fileRenderCmdKongFileOutput, "output-file", "o",
+		"-", "file to which to write Kong's configuration."+
+			"Use `-` to write to stdout.")
+	renderCmd.Flags().StringVar(&fileRenderCmdStateFormat, "format",
+		"yaml", "output file format: json or yaml.")
+
+	return renderCmd
+}

cmd/root.go

@@ -224,6 +224,7 @@ It can be used to export, import, or sync entities to Kong.`,
 		fileCmd.AddCommand(newMergeCmd())
 		fileCmd.AddCommand(newPatchCmd())
 		fileCmd.AddCommand(newOpenapi2KongCmd())
+		fileCmd.AddCommand(newFileRenderCmd())
 	}
 	return rootCmd
 }

cmd/validate.go

@@ -44,7 +44,7 @@ this command unless --online flag is used.
 			_ = sendAnalytics("validate", "", mode)
 			// read target file
 			// this does json schema validation as well
-			targetContent, err := file.GetContentFromFiles(validateCmdKongStateFile)
+			targetContent, err := file.GetContentFromFiles(validateCmdKongStateFile, false)
 			if err != nil {
 				return err
 			}

convert/.gitignore

@@ -0,0 +1 @@
+output.yaml

convert/convert.go

@@ -1,18 +1,24 @@
 package convert
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
+	"github.com/blang/semver/v4"
 	"github.com/kong/deck/cprint"
+	"github.com/kong/deck/dump"
 	"github.com/kong/deck/file"
+	"github.com/kong/deck/state"
 	"github.com/kong/deck/utils"
 	"github.com/kong/go-kong/kong"
 )
 
 type Format string
 
 const (
+	// FormatDistributed represents the Deck configuration format.
+	FormatDistributed Format = "distributed"
 	// FormatKongGateway represents the Kong gateway format.
 	FormatKongGateway Format = "kong-gateway"
 	// FormatKonnect represents the Konnect format.
@@ -37,42 +43,61 @@ func ParseFormat(key string) (Format, error) {
 		return FormatKongGateway2x, nil
 	case FormatKongGateway3x:
 		return FormatKongGateway3x, nil
+	case FormatDistributed:
+		return FormatDistributed, nil
 	default:
 		return "", fmt.Errorf("invalid format: '%v'", key)
 	}
 }
 
-func Convert(inputFilename, outputFilename string, from, to Format) error {
-	var (
-		outputContent *file.Content
-		err           error
-	)
+func Convert(
+	inputFilenames []string,
+	outputFilename string,
+	outputFormat file.Format,
+	from Format,
+	to Format,
+	mockEnvVars bool,
+) error {
+	var outputContent *file.Content
 
-	inputContent, err := file.GetContentFromFiles([]string{inputFilename})
+	inputContent, err := file.GetContentFromFiles(inputFilenames, mockEnvVars)
 	if err != nil {
 		return err
 	}
 
 	switch {
 	case from == FormatKongGateway && to == FormatKonnect:
+		if len(inputFilenames) > 1 {
+			return fmt.Errorf("only one input file can be provided when converting from Kong to Konnect format")
+		}
 		outputContent, err = convertKongGatewayToKonnect(inputContent)
 		if err != nil {
 			return err
 		}
+
 	case from == FormatKongGateway2x && to == FormatKongGateway3x:
-		outputContent, err = convertKongGateway2xTo3x(inputContent, inputFilename)
+		if len(inputFilenames) > 1 {
+			return fmt.Errorf("only one input file can be provided when converting from Kong 2.x to Kong 3.x format")
+		}
+		outputContent, err = convertKongGateway2xTo3x(inputContent, inputFilenames[0])
 		if err != nil {
 			return err
 		}
+
+	case from == FormatDistributed && to == FormatKongGateway,
+		from == FormatDistributed && to == FormatKongGateway2x,
+		from == FormatDistributed && to == FormatKongGateway3x:
+		outputContent, err = convertDistributedToKong(inputContent, outputFilename, outputFormat, to)
+		if err != nil {
+			return err
+		}
+
 	default:
 		return fmt.Errorf("cannot convert from '%s' to '%s' format", from, to)
 	}
 
-	err = file.WriteContentToFile(outputContent, outputFilename, file.YAML)
-	if err != nil {
-		return err
-	}
-	return nil
+	err = file.WriteContentToFile(outputContent, outputFilename, outputFormat)
+	return err
 }
 
 func convertKongGateway2xTo3x(input *file.Content, filename string) (*file.Content, error) {
@@ -195,3 +220,43 @@ func removeServiceName(service *file.FService) *file.FService {
 	serviceCopy.ID = kong.String(utils.UUID())
 	return serviceCopy
 }
+
+// convertDistributedToKong is used to convert one or many distributed format
+// files to create one Kong Gateway declarative config. It also leverages some
+// deck features like the defaults/centralized plugin configurations.
+func convertDistributedToKong(
+	targetContent *file.Content,
+	outputFilename string,
+	format file.Format,
+	kongFormat Format,
+) (*file.Content, error) {
+	var version semver.Version
+
+	switch kongFormat { //nolint:exhaustive
+	case FormatKongGateway,
+		FormatKongGateway3x:
+		version = semver.Version{Major: 3, Minor: 0}
+	case FormatKongGateway2x:
+		version = semver.Version{Major: 2, Minor: 8}
+	}
+
+	s, _ := state.NewKongState()
+	rawState, err := file.Get(context.Background(), targetContent, file.RenderConfig{
+		CurrentState: s,
+		KongVersion:  version,
+	}, dump.Config{}, nil)
+	if err != nil {
+		return nil, err
+	}
+	targetState, err := state.Get(rawState)
+	if err != nil {
+		return nil, err
+	}
+
+	// file.KongStateToContent calls file.WriteContentToFile
+	return file.KongStateToContent(targetState, file.WriteConfig{
+		Filename:    outputFilename,
+		FileFormat:  format,
+		KongVersion: version.String(),
+	})
+}