Improve Ignition conversions handling

Maintaining Ignition conversions is starting to be more and more
complicated since each new version requires not only to code the
conversion logic (by calling the underlaying Ignition converter) but
adding the version to the MCS logic, update each comment that points to
the old version or the supported version list, etc.
This change aims to simplify the new Ignition bumps by providing a
recursive converter that handles conversion between known versions
transparently and exposes methods to retrieve the supported versions and
to perform a coversion between known source and target versions.
With this change, the dev in future Ignition bumps, will only need to
bump the Ignition dependency and add two tiny functions that converts to
and from the previous ignition version.

Author: pablintino

pkg/controller/common/helpers.go

@@ -9,6 +9,7 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
+	"github.com/coreos/go-semver/semver"
 	"io"
 	"io/fs"
 	"net/url"
@@ -22,30 +23,13 @@ import (
 
 	"github.com/clarketm/json"
 	fcctbase "github.com/coreos/fcct/base/v0_1"
-	"github.com/coreos/ign-converter/translate/v23tov30"
-	"github.com/coreos/ign-converter/translate/v32tov22"
-	"github.com/coreos/ign-converter/translate/v32tov31"
-	"github.com/coreos/ign-converter/translate/v33tov32"
-	"github.com/coreos/ign-converter/translate/v34tov33"
-	"github.com/coreos/ign-converter/translate/v35tov34"
 	ign2error "github.com/coreos/ignition/config/shared/errors"
 	ign2 "github.com/coreos/ignition/config/v2_2"
 	ign2types "github.com/coreos/ignition/config/v2_2/types"
-	ign2_3 "github.com/coreos/ignition/config/v2_3"
 	validate2 "github.com/coreos/ignition/config/validate"
 	ign3error "github.com/coreos/ignition/v2/config/shared/errors"
-	translate3_1 "github.com/coreos/ignition/v2/config/v3_1/translate"
-	ign3_1types "github.com/coreos/ignition/v2/config/v3_1/types"
-	translate3_2 "github.com/coreos/ignition/v2/config/v3_2/translate"
-	ign3_2types "github.com/coreos/ignition/v2/config/v3_2/types"
-	translate3_3 "github.com/coreos/ignition/v2/config/v3_3/translate"
-	ign3_3types "github.com/coreos/ignition/v2/config/v3_3/types"
-	translate3_4 "github.com/coreos/ignition/v2/config/v3_4/translate"
-	ign3_4types "github.com/coreos/ignition/v2/config/v3_4/types"
 
 	ign3 "github.com/coreos/ignition/v2/config/v3_5"
-	ign3_5 "github.com/coreos/ignition/v2/config/v3_5"
-	translate3 "github.com/coreos/ignition/v2/config/v3_5/translate"
 	ign3types "github.com/coreos/ignition/v2/config/v3_5/types"
 	validate3 "github.com/coreos/ignition/v2/config/validate"
 	"github.com/ghodss/yaml"
@@ -291,9 +275,7 @@ func ConvertRawExtIgnitionToV3_5(inRawExtIgn *runtime.RawExtension) (runtime.Raw
 	return outRawExt, nil
 }
 
-// ConvertRawExtIgnitionToV3_4 ensures that the Ignition config in
-// the RawExtension is spec v3.4, or translates to it.
-func ConvertRawExtIgnitionToV3_4(inRawExtIgn *runtime.RawExtension) (runtime.RawExtension, error) {
+func ConvertRawExtIgnitionToVersion(inRawExtIgn *runtime.RawExtension, targetVersion semver.Version) (runtime.RawExtension, error) {
 	rawExt, err := ConvertRawExtIgnitionToV3_5(inRawExtIgn)
 	if err != nil {
 		return runtime.RawExtension{}, err
@@ -304,262 +286,17 @@ func ConvertRawExtIgnitionToV3_4(inRawExtIgn *runtime.RawExtension) (runtime.Raw
 		return runtime.RawExtension{}, fmt.Errorf("parsing Ignition config failed with error: %w\nReport: %v", errV3, rptV3)
 	}
 
-	// TODO(jkyros): someday we should write a recursive chain-downconverter, but until then,
-	// we're going to do it the hard way
-	ignCfgV33, err := convertIgnition35to34(ignCfgV3)
+	conversion, err := ignitionConverter.Convert(ignCfgV3, ign3types.MaxVersion, targetVersion)
 	if err != nil {
 		return runtime.RawExtension{}, err
 	}
 
-	outIgnV33, err := json.Marshal(ignCfgV33)
+	out, err := json.Marshal(conversion)
 	if err != nil {
 		return runtime.RawExtension{}, fmt.Errorf("failed to marshal converted config: %w", err)
 	}
 
-	outRawExt := runtime.RawExtension{}
-	outRawExt.Raw = outIgnV33
-
-	return outRawExt, nil
-}
-
-// ConvertRawExtIgnitionToV3_3 ensures that the Ignition config in
-// the RawExtension is spec v3.3, or translates to it.
-func ConvertRawExtIgnitionToV3_3(inRawExtIgn *runtime.RawExtension) (runtime.RawExtension, error) {
-	rawExt, err := ConvertRawExtIgnitionToV3_5(inRawExtIgn)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV3, rptV3, errV3 := ign3.Parse(rawExt.Raw)
-	if errV3 != nil || rptV3.IsFatal() {
-		return runtime.RawExtension{}, fmt.Errorf("parsing Ignition config failed with error: %w\nReport: %v", errV3, rptV3)
-	}
-
-	// TODO(jkyros): someday we should write a recursive chain-downconverter, but until then,
-	// we're going to do it the hard way
-	ignCfgV34, err := convertIgnition35to34(ignCfgV3)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV33, err := convertIgnition34to33(ignCfgV34)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	outIgnV33, err := json.Marshal(ignCfgV33)
-	if err != nil {
-		return runtime.RawExtension{}, fmt.Errorf("failed to marshal converted config: %w", err)
-	}
-
-	outRawExt := runtime.RawExtension{}
-	outRawExt.Raw = outIgnV33
-
-	return outRawExt, nil
-}
-
-// ConvertRawExtIgnitionToV3_2 ensures that the Ignition config in
-// the RawExtension is spec v3.2, or translates to it.
-func ConvertRawExtIgnitionToV3_2(inRawExtIgn *runtime.RawExtension) (runtime.RawExtension, error) {
-	rawExt, err := ConvertRawExtIgnitionToV3_5(inRawExtIgn)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV3, rptV3, errV3 := ign3.Parse(rawExt.Raw)
-	if errV3 != nil || rptV3.IsFatal() {
-		return runtime.RawExtension{}, fmt.Errorf("parsing Ignition config failed with error: %w\nReport: %v", errV3, rptV3)
-	}
-
-	// TODO(jkyros): someday we should write a recursive chain-downconverter, but until then,
-	// we're going to do it the hard way
-	ignCfgV34, err := convertIgnition35to34(ignCfgV3)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV33, err := convertIgnition34to33(ignCfgV34)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV32, err := convertIgnition33to32(ignCfgV33)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	outIgnV32, err := json.Marshal(ignCfgV32)
-	if err != nil {
-		return runtime.RawExtension{}, fmt.Errorf("failed to marshal converted config: %w", err)
-	}
-
-	outRawExt := runtime.RawExtension{}
-	outRawExt.Raw = outIgnV32
-
-	return outRawExt, nil
-}
-
-// ConvertRawExtIgnitionToV3_1 ensures that the Ignition config in
-// the RawExtension is spec v3.1, or translates to it.
-func ConvertRawExtIgnitionToV3_1(inRawExtIgn *runtime.RawExtension) (runtime.RawExtension, error) {
-	rawExt, err := ConvertRawExtIgnitionToV3_5(inRawExtIgn)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV3, rptV3, errV3 := ign3.Parse(rawExt.Raw)
-	if errV3 != nil || rptV3.IsFatal() {
-		return runtime.RawExtension{}, fmt.Errorf("parsing Ignition config failed with error: %w\nReport: %v", errV3, rptV3)
-	}
-
-	// TODO(jkyros): someday we should write a recursive chain-downconverter, but until then,
-	// we're going to do it the hard way
-	ignCfgV34, err := convertIgnition35to34(ignCfgV3)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV33, err := convertIgnition34to33(ignCfgV34)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV32, err := convertIgnition33to32(ignCfgV33)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	ignCfgV31, err := convertIgnition32to31(ignCfgV32)
-	if err != nil {
-		return runtime.RawExtension{}, err
-	}
-
-	outIgnV31, err := json.Marshal(ignCfgV31)
-	if err != nil {
-		return runtime.RawExtension{}, fmt.Errorf("failed to marshal converted config: %w", err)
-	}
-
-	outRawExt := runtime.RawExtension{}
-	outRawExt.Raw = outIgnV31
-
-	return outRawExt, nil
-}
-
-// ConvertRawExtIgnitionToV2 ensures that the Ignition config in
-// the RawExtension is spec v2.2, or translates to it.
-func ConvertRawExtIgnitionToV2_2(inRawExtIgn *runtime.RawExtension) (runtime.RawExtension, error) {
-	ignCfg, rpt, err := ign3.Parse(inRawExtIgn.Raw)
-	if err != nil || rpt.IsFatal() {
-		return runtime.RawExtension{}, fmt.Errorf("parsing Ignition config spec v3.2 failed with error: %w\nReport: %v", err, rpt)
-	}
-
-	converted2, err := convertIgnition35to22(ignCfg)
-	if err != nil {
-		return runtime.RawExtension{}, fmt.Errorf("failed to convert config from spec v3.2 to v2.2: %w", err)
-	}
-
-	outIgnV2, err := json.Marshal(converted2)
-	if err != nil {
-		return runtime.RawExtension{}, fmt.Errorf("failed to marshal converted config: %w", err)
-	}
-
-	outRawExt := runtime.RawExtension{}
-	outRawExt.Raw = outIgnV2
-
-	return outRawExt, nil
-}
-
-// convertIgnition2to3 takes an ignition spec v2.2 config and returns a v3.5 config
-func convertIgnition22to35(ign2config ign2types.Config) (ign3types.Config, error) {
-	// only support writing to root file system
-	fsMap := map[string]string{
-		"root": "/",
-	}
-
-	// Workaround to get v2.3 as input for converter
-	ign2_3config := ign2_3.Translate(ign2config)
-	ign3_0config, err := v23tov30.Translate(ign2_3config, fsMap)
-	if err != nil {
-		return ign3types.Config{}, fmt.Errorf("unable to convert Ignition spec v2 config to v3: %w", err)
-	}
-	// Workaround to get a v3.5 config as output
-	converted3 := translate3.Translate(translate3_4.Translate(translate3_3.Translate(translate3_2.Translate(translate3_1.Translate(ign3_0config)))))
-
-	klog.V(4).Infof("Successfully translated Ignition spec v2 config to Ignition spec v3 config: %v", converted3)
-	return converted3, nil
-}
-
-// convertIgnition3to2 takes an ignition spec v3.5 config and returns a v2.2 config
-func convertIgnition35to22(ign3config ign3types.Config) (ign2types.Config, error) {
-
-	// TODO(jkyros): that recursive down-converter is looking like a better idea all the time
-
-	converted34, err := convertIgnition35to34(ign3config)
-	if err != nil {
-		return ign2types.Config{}, fmt.Errorf("unable to convert Ignition spec v3 config to v2: %w", err)
-	}
-
-	converted33, err := convertIgnition34to33(converted34)
-	if err != nil {
-		return ign2types.Config{}, fmt.Errorf("unable to convert Ignition spec v3 config to v2: %w", err)
-	}
-
-	converted32, err := convertIgnition33to32(converted33)
-	if err != nil {
-		return ign2types.Config{}, fmt.Errorf("unable to convert Ignition spec v3 config to v2: %w", err)
-	}
-
-	converted2, err := v32tov22.Translate(converted32)
-	if err != nil {
-		return ign2types.Config{}, fmt.Errorf("unable to convert Ignition spec v3 config to v2: %w", err)
-	}
-	klog.V(4).Infof("Successfully translated Ignition spec v3 config to Ignition spec v2 config: %v", converted2)
-
-	return converted2, nil
-}
-
-// convertIgnition35to34 takes an ignition spec v3.5 config and returns a v3.4 config
-func convertIgnition35to34(ign3config ign3types.Config) (ign3_4types.Config, error) {
-	converted34, err := v35tov34.Translate(ign3config)
-	if err != nil {
-		return ign3_4types.Config{}, fmt.Errorf("unable to convert Ignition spec v3.5 config to v3.4: %w", err)
-	}
-	klog.V(4).Infof("Successfully translated Ignition spec v3.5 config to Ignition spec v3.4 config: %v", converted34)
-
-	return converted34, nil
-}
-
-// convertIgnition34to33 takes an ignition spec v3.4 config and returns a v3.3 config
-func convertIgnition34to33(ign3config ign3_4types.Config) (ign3_3types.Config, error) {
-	converted33, err := v34tov33.Translate(ign3config)
-	if err != nil {
-		return ign3_3types.Config{}, fmt.Errorf("unable to convert Ignition spec v3.2 config to v3.1: %w", err)
-	}
-	klog.V(4).Infof("Successfully translated Ignition spec v3.2 config to Ignition spec v3.1 config: %v", converted33)
-
-	return converted33, nil
-}
-
-// convertIgnition33to32 takes an ignition spec v3.3 config and returns a v3.2 config
-func convertIgnition33to32(ign3config ign3_3types.Config) (ign3_2types.Config, error) {
-	converted32, err := v33tov32.Translate(ign3config)
-	if err != nil {
-		return ign3_2types.Config{}, fmt.Errorf("unable to convert Ignition spec v3.3 config to v3.2: %w", err)
-	}
-	klog.V(4).Infof("Successfully translated Ignition spec v3.3 config to Ignition spec v3.2 config: %v", converted32)
-
-	return converted32, nil
-}
-
-// convertIgnition32to31 takes an ignition spec v3.2 config and returns a v3.1 config
-func convertIgnition32to31(ign3config ign3_2types.Config) (ign3_1types.Config, error) {
-	converted31, err := v32tov31.Translate(ign3config)
-	if err != nil {
-		return ign3_1types.Config{}, fmt.Errorf("unable to convert Ignition spec v3.2 config to v3.1: %w", err)
-	}
-	klog.V(4).Infof("Successfully translated Ignition spec v3.2 config to Ignition spec v3.1 config: %v", converted31)
-
-	return converted31, nil
+	return runtime.RawExtension{Raw: out}, nil
 }
 
 // ValidateIgnition wraps the underlying Ignition V2/V3 validation, but explicitly supports
@@ -746,7 +483,7 @@ func SupportedExtensions() map[string][]string {
 // a V2 or V3 Config or an error. This wrapper is necessary since V2 and V3 use different parsers.
 func IgnParseWrapper(rawIgn []byte) (interface{}, error) {
 	// ParseCompatibleVersion will parse any config <= N to version N
-	ignCfgV3, rptV3, errV3 := ign3_5.ParseCompatibleVersion(rawIgn)
+	ignCfgV3, rptV3, errV3 := ign3.ParseCompatibleVersion(rawIgn)
 	if errV3 == nil && !rptV3.IsFatal() {
 		return ignCfgV3, nil
 	}
@@ -755,7 +492,8 @@ func IgnParseWrapper(rawIgn []byte) (interface{}, error) {
 	// ErrInvalidVersion ("I can't parse it to find out what it is"), but our old 3.2 logic didn't, so this is here to make sure
 	// our error message for invalid version is still helpful.
 	if errV3.Error() == ign3error.ErrInvalidVersion.Error() {
-		return ign3types.Config{}, fmt.Errorf("parsing Ignition config failed: invalid version. Supported spec versions: 2.2, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5")
+		versions := strings.TrimSuffix(strings.Join(IgnitionConverterSingleton().GetSupportedMinorVersions(), ","), ",")
+		return ign3types.Config{}, fmt.Errorf("parsing Ignition config failed: invalid version. Supported spec versions: %s", versions)
 	}
 
 	if errV3.Error() == ign3error.ErrUnknownVersion.Error() {
@@ -766,7 +504,8 @@ func IgnParseWrapper(rawIgn []byte) (interface{}, error) {
 
 		// If the error is still UnknownVersion it's not a 3.3/3.2/3.1/3.0 or 2.x config, thus unsupported
 		if errV2.Error() == ign2error.ErrUnknownVersion.Error() {
-			return ign3types.Config{}, fmt.Errorf("parsing Ignition config failed: unknown version. Supported spec versions: 2.2, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5")
+			versions := strings.TrimSuffix(strings.Join(IgnitionConverterSingleton().GetSupportedMinorVersions(), ","), ",")
+			return ign3types.Config{}, fmt.Errorf("parsing Ignition config failed: unknown version. Supported spec versions: %s", versions)
 		}
 		return ign3types.Config{}, fmt.Errorf("parsing Ignition spec v2 failed with error: %v\nReport: %v", errV2, rptV2)
 	}
@@ -790,11 +529,11 @@ func ParseAndConvertConfig(rawIgn []byte) (ign3types.Config, error) {
 		if err != nil {
 			return ign3types.Config{}, err
 		}
-		convertedIgnV3, err := convertIgnition22to35(ignconfv2)
+		convertedIgnV3, err := ignitionConverter.Convert(ignconfv2, *semver.New(ignconfv2.Ignition.Version), ign3types.MaxVersion)
 		if err != nil {
 			return ign3types.Config{}, fmt.Errorf("failed to convert Ignition config spec v2 to v3: %w", err)
 		}
-		return convertedIgnV3, nil
+		return convertedIgnV3.(ign3types.Config), nil
 	default:
 		return ign3types.Config{}, fmt.Errorf("unexpected type for ignition config: %v", typedConfig)
 	}
@@ -990,13 +729,15 @@ func TranspileCoreOSConfigToIgn(files, units []string) (*ign3types.Config, error
 		// Add the file to the config
 		var ctCfg fcctbase.Config
 		ctCfg.Storage.Files = append(ctCfg.Storage.Files, *f)
-		ign3_0config, tSet, err := ctCfg.ToIgn3_0()
+		ign30Config, tSet, err := ctCfg.ToIgn3_0()
 		if err != nil {
 			return nil, fmt.Errorf("failed to transpile config to Ignition config %w\nTranslation set: %v", err, tSet)
 		}
-		// TODO(jkyros): do we keep just...adding translations forever as we add more versions? :)
-		ign3Config := translate3.Translate(translate3_4.Translate(translate3_3.Translate(translate3_2.Translate(translate3_1.Translate(ign3_0config)))))
-		outConfig = ign3.Merge(outConfig, ign3Config)
+		ign3Config, err := ignitionConverter.Convert(ign30Config, *semver.New("3.0.0"), ign3types.MaxVersion)
+		if err != nil {
+			return nil, fmt.Errorf("failed to convert config from 3.0 to %v. %w", ign3types.MaxVersion, err)
+		}
+		outConfig = ign3.Merge(outConfig, ign3Config.(ign3types.Config))
 	}
 
 	for _, contents := range units {
@@ -1008,12 +749,15 @@ func TranspileCoreOSConfigToIgn(files, units []string) (*ign3types.Config, error
 		// Add the unit to the config
 		var ctCfg fcctbase.Config
 		ctCfg.Systemd.Units = append(ctCfg.Systemd.Units, *u)
-		ign3_0config, tSet, err := ctCfg.ToIgn3_0()
+		ign30Config, tSet, err := ctCfg.ToIgn3_0()
 		if err != nil {
 			return nil, fmt.Errorf("failed to transpile config to Ignition config %w\nTranslation set: %v", err, tSet)
 		}
-		ign3Config := translate3.Translate(translate3_4.Translate(translate3_3.Translate(translate3_2.Translate(translate3_1.Translate(ign3_0config)))))
-		outConfig = ign3.Merge(outConfig, ign3Config)
+		ign3Config, err := ignitionConverter.Convert(ign30Config, *semver.New("3.0.0"), ign3types.MaxVersion)
+		if err != nil {
+			return nil, fmt.Errorf("failed to convert config from 3.0 to %v. %w", ign3types.MaxVersion, err)
+		}
+		outConfig = ign3.Merge(outConfig, ign3Config.(ign3types.Config))
 	}
 
 	return &outConfig, nil