fix(unikontainers): warn on vAccel misconfiguration

Introduce ErrVAccelDisabled to distinguish missing vAccel config
from actual misconfiguration. Log Warn instead of Debug on error.

Fixes: #698
Signed-off-by: Chennamma-Hotkar <channuhotkar@gmail.com>

Author: Chennamma-Hotkar

pkg/unikontainers/unikontainers.go

@@ -528,7 +528,9 @@ func (u *Unikontainer) Exec(metrics m.Writer) error {
 	// vAccel setup
 	vAccelType, vsockSocketPath, rpcAddress, err := resolveVAccelConfig(u.State.Annotations[annotHypervisor], u.Spec.Annotations)
 	if err != nil {
-		uniklog.Debugf("vAccel config: %v", err)
+		if !errors.Is(err, ErrVAccelDisabled) {
+			uniklog.Warnf("vAccel misconfiguration: %v", err)
+		}
 	}
 
 	if vAccelType == "vsock" && err == nil {

pkg/unikontainers/vaccel.go

@@ -15,12 +15,17 @@
 package unikontainers
 
 import (
+	"errors"
 	"fmt"
 	"regexp"
 
 	"golang.org/x/sys/unix"
 )
 
+// ErrVAccelDisabled is returned by resolveVAccelConfig when the vAccel
+// annotation is absent. This is an expected condition, not a misconfiguration.
+var ErrVAccelDisabled = errors.New("vaccel is disabled")
+
 // idToGuestCID generates a deterministic guest CID (Context Identifier)
 // for vsock communication based on a container or VM ID.
 func idToGuestCID(id string) int {
@@ -87,8 +92,7 @@ func resolveVAccelConfig(hypervisor string, annotations map[string]string) (stri
 			return vAccelType, "", "", err
 		}
 	} else {
-		err = fmt.Errorf("vaccel is disabled")
-		return vAccelType, "", "", err
+		return "", "", "", ErrVAccelDisabled
 	}
 
 	if vAccelType == "vsock" {

pkg/unikontainers/vaccel_test.go

@@ -15,6 +15,7 @@
 package unikontainers
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -168,3 +169,46 @@ func TestIsValidVSockAddress(t *testing.T) {
 		})
 	}
 }
+
+func TestResolveVAccelConfig(t *testing.T) {
+	t.Run("vaccel disabled returns ErrVAccelDisabled", func(t *testing.T) {
+		t.Parallel()
+		annotations := map[string]string{}
+		_, _, _, err := resolveVAccelConfig("qemu", annotations)
+		assert.ErrorIs(t, err, ErrVAccelDisabled)
+	})
+
+	t.Run("vaccel enabled but rpc address missing returns error", func(t *testing.T) {
+		t.Parallel()
+		annotations := map[string]string{
+			"com.urunc.unikernel.vAccel": "vsock",
+		}
+		_, _, _, err := resolveVAccelConfig("qemu", annotations)
+		assert.Error(t, err)
+		assert.False(t, errors.Is(err, ErrVAccelDisabled), "missing rpc address should not be ErrVAccelDisabled")
+	})
+
+	t.Run("vaccel enabled with malformed rpc address returns error", func(t *testing.T) {
+		t.Parallel()
+		annotations := map[string]string{
+			"com.urunc.unikernel.vAccel":      "vsock",
+			"com.urunc.unikernel.RPCAddress":  "invalid-address",
+		}
+		_, _, _, err := resolveVAccelConfig("qemu", annotations)
+		assert.Error(t, err)
+		assert.False(t, errors.Is(err, ErrVAccelDisabled), "malformed address should not be ErrVAccelDisabled")
+	})
+
+	t.Run("vaccel enabled with valid qemu vsock address succeeds", func(t *testing.T) {
+		t.Parallel()
+		annotations := map[string]string{
+			"com.urunc.unikernel.vAccel":     "vsock",
+			"com.urunc.unikernel.RPCAddress": "vsock://2:1234",
+		}
+		vAccelType, _, addr, err := resolveVAccelConfig("qemu", annotations)
+		assert.NoError(t, err)
+		assert.Equal(t, "vsock", vAccelType)
+		assert.Equal(t, "vsock://2:1234", addr)
+	})
+}
+