fix: read multi-doc machine config with newer talosctl

smira · smira · commit 1f989dfb0318 · 2026-03-06T19:00:33.000+04:00
This affects reading multi-doc machine config via `talosctl` from Talos machines v1.11 and below by `talosctl` of v1.12 and up. The problem is that before v1.12 Talos returned machine config as embedded document instead of the spec if the resource, which was not valid YAML. It worked via hacks we used in our fork of yaml library. Talos v1.12+ cleans that up by marshaling the config as a string, and drops the forked library. The problem is that we can't still pass multi-doc YAML via this path, so we have to resort to going into COSI internals to retrieve the actual value as written by Talos API. Note: there is no problem for Omni, as it goes via protobuf path which hasn't been affected. Fixes #12787 Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com> (cherry picked from commit f118ee4)
diff --git a/cmd/talosctl/cmd/talos/output/yaml.go b/cmd/talosctl/cmd/talos/output/yaml.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/cosi-project/runtime/pkg/resource"
 	"github.com/cosi-project/runtime/pkg/resource/meta"
+	"github.com/cosi-project/runtime/pkg/resource/protobuf"
 	"github.com/cosi-project/runtime/pkg/state"
 	yaml "go.yaml.in/yaml/v4"
 
@@ -80,6 +81,20 @@ func (m *mcYamlRepr) Spec() any { return &mcYamlSpec{res: m.Resource} }
 type mcYamlSpec struct{ res resource.Resource }
 
 func (m *mcYamlSpec) MarshalYAML() (any, error) {
+	// this is backwards compatibility for versions of Talos which marshaled the MachineConfig spec as a YAML document
+	// instead of putting it as string
+	//
+	// if try to go via yaml.Marshal path, it will cut off all documents after the first one (as there is no way to return
+	// multiple documents from MarshalYAML), so we need to extract the original body from the resource
+	if pb, ok := m.res.(*protobuf.Resource); ok {
+		p, err := pb.Marshal()
+		if err != nil {
+			return nil, fmt.Errorf("marshal protobuf resource: %w", err)
+		}
+
+		return p.GetSpec().GetYamlSpec(), nil
+	}
+
 	out, err := yaml.Marshal(m.res.Spec())
 	if err != nil {
 		return nil, err
diff --git a/cmd/talosctl/cmd/talos/patch.go b/cmd/talosctl/cmd/talos/patch.go
@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/cosi-project/runtime/pkg/resource"
+	"github.com/cosi-project/runtime/pkg/resource/protobuf"
 	"github.com/spf13/cobra"
 	"go.yaml.in/yaml/v4"
 	"google.golang.org/protobuf/types/known/durationpb"
@@ -38,6 +39,20 @@ var patchCmdFlags struct {
 
 func extractMachineConfigBody(mc resource.Resource) ([]byte, error) {
 	if mc.Metadata().Annotations().Empty() {
+		// this is backwards compatibility for versions of Talos which marshaled the MachineConfig spec as a YAML document
+		// instead of putting it as string
+		//
+		// if try to go via yaml.Marshal path, it will cut off all documents after the first one (as there is no way to return
+		// multiple documents from MarshalYAML), so we need to extract the original body from the resource
+		if pb, ok := mc.(*protobuf.Resource); ok {
+			p, err := pb.Marshal()
+			if err != nil {
+				return nil, fmt.Errorf("marshal protobuf resource: %w", err)
+			}
+
+			return []byte(p.GetSpec().GetYamlSpec()), nil
+		}
+
 		return yaml.Marshal(mc.Spec())
 	}
 
