Support providing and translating Butane configs via library

config/config.go

@@ -15,14 +15,33 @@
 package config
 
 import (
+	"github.com/coreos/ignition/v2/config/shared/errors"
 	exp "github.com/coreos/ignition/v2/config/v3_6_experimental"
 	types_exp "github.com/coreos/ignition/v2/config/v3_6_experimental/types"
+	"github.com/coreos/ignition/v2/config/util"
 
+	butane_config "github.com/coreos/butane/config"
+	butane_config_common "github.com/coreos/butane/config/common"
 	"github.com/coreos/vcontext/report"
 )
 
 // Parse parses a config of any supported version and returns the equivalent config at the latest
 // supported version.
 func Parse(raw []byte) (types_exp.Config, report.Report, error) {
-	return exp.ParseCompatibleVersion(raw)
+	// Try first to see if it's JSON/Ignition config
+	_, rpt, err := util.GetConfigVersion(raw)
+	if err == nil {
+		return exp.ParseCompatibleVersion(raw)
+	} else if err == errors.ErrInvalid {
+		// It was invalid JSON, but may be valid Butane (YAML)
+		out, rpt, err := butane_config.TranslateBytes(raw, butane_config_common.TranslateBytesOptions{})
+		if err != nil {
+			return types_exp.Config{}, rpt, err
+		} else {
+			// We translated Butane into Ignition. Now let's Parse the Ignition
+			return exp.ParseCompatibleVersion(out)
+		}
+	} else {
+		return types_exp.Config{}, rpt, err
+	}
 }

go.mod

@@ -45,7 +45,9 @@ require (
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.53.0 // indirect
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.53.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/clarketm/json v1.17.1 // indirect
 	github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 // indirect
+	github.com/coreos/butane v0.24.0 // indirect
 	github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect

go.sum

@@ -50,10 +50,14 @@ github.com/beevik/etree v1.5.1 h1:TC3zyxYp+81wAmbsi8SWUpZCurbxa6S8RITYRSkNRwo=
 github.com/beevik/etree v1.5.1/go.mod h1:gPNJNaBGVZ9AwsidazFZyygnd+0pAU38N4D+WemwKNs=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/clarketm/json v1.17.1 h1:U1IxjqJkJ7bRK4L6dyphmoO840P6bdhPdbbLySourqI=
+github.com/clarketm/json v1.17.1/go.mod h1:ynr2LRfb0fQU34l07csRNBTcivjySLLiY1YzQqKVfdo=
 github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 h1:aQ3y1lwWyqYPiWZThqv1aFbZMiM9vblcSArJRf2Irls=
 github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
 github.com/containers/libhvee v0.10.0 h1:7VLv8keWZpHuGmWvyY4c1mVH5V1JYb1G78VC+8AlrM0=
 github.com/containers/libhvee v0.10.0/go.mod h1:at0h8lRcK5jCKfQgU/e6Io0Mw12F36zRLjXVOXRoDTM=
+github.com/coreos/butane v0.24.0 h1:sput//CnGz1ZUNT3TaSpbgjAjlefGC+/Ikiiwl5wO9Q=
+github.com/coreos/butane v0.24.0/go.mod h1:mLu58/AgW6lC116Rf/9N5b+ixj/zdhRtABBZjADHWFo=
 github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb h1:rmqyI19j3Z/74bIRhuC59RB442rXUazKNueVpfJPxg4=
 github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb/go.mod h1:rcFZM3uxVvdyNmsAV2jopgPD1cs5SPWJWU5dOz2LUnw=
 github.com/coreos/go-semver v0.3.1 h1:yi21YpKnrx1gt5R+la8n5WgS0kCrsPp33dmEyHReZr4=