Fix random ETag values due to map ordering

cmd/incusd/instance_patch.go

@@ -102,8 +102,7 @@ func instancePatch(d *Daemon, r *http.Request) response.Response {
 	}
 
 	// Validate the ETag
-	etag := []any{c.Architecture(), c.LocalConfig(), c.LocalDevices(), c.IsEphemeral(), c.Profiles()}
-	err = localUtil.EtagCheck(r, etag)
+	err = localUtil.EtagCheck(r, c.ETag())
 	if err != nil {
 		return response.PreconditionFailed(err)
 	}

cmd/incusd/instance_put.go

@@ -110,8 +110,7 @@ func instancePut(d *Daemon, r *http.Request) response.Response {
 	}
 
 	// Validate the ETag
-	etag := []any{inst.Architecture(), inst.LocalConfig(), inst.LocalDevices(), inst.IsEphemeral(), inst.Profiles()}
-	err = localUtil.EtagCheck(r, etag)
+	err = localUtil.EtagCheck(r, inst.ETag())
 	if err != nil {
 		return response.PreconditionFailed(err)
 	}

internal/server/instance/drivers/driver_common.go

@@ -1589,3 +1589,26 @@ func (d *common) processStartedAt(pid int) (time.Time, error) {
 
 	return time.Unix(int64(linuxInfo.Ctim.Sec), int64(linuxInfo.Ctim.Nsec)), nil
 }
+
+// ETag returns the instance configuration ETag data for pre-condition validation.
+func (d *common) ETag() []any {
+	if d.IsSnapshot() {
+		return []any{d.expiryDate}
+	}
+
+	// Prepare the ETag
+	etag := []any{d.architecture, d.ephemeral, d.profiles, d.localDevices.Sorted()}
+
+	configKeys := make([]string, 0, len(d.localConfig))
+	for k := range d.localConfig {
+		configKeys = append(configKeys, k)
+	}
+
+	sort.Strings(configKeys)
+
+	for _, k := range configKeys {
+		etag = append(etag, fmt.Sprintf("%s=%s", k, d.localConfig[k]))
+	}
+
+	return etag
+}

internal/server/instance/drivers/driver_lxc.go

@@ -3531,9 +3531,7 @@ func (d *lxc) Render(options ...func(response any) error) (any, any, error) {
 	}
 
 	if d.IsSnapshot() {
-		// Prepare the ETag
-		etag := []any{d.expiryDate}
-
+		// Prepare the response.
 		snapState := api.InstanceSnapshot{
 			CreatedAt:       d.creationDate,
 			ExpandedConfig:  d.expandedConfig,
@@ -3558,12 +3556,10 @@ func (d *lxc) Render(options ...func(response any) error) (any, any, error) {
 			}
 		}
 
-		return &snapState, etag, nil
+		return &snapState, d.ETag(), nil
 	}
 
-	// Prepare the ETag
-	etag := []any{d.architecture, d.localConfig, d.localDevices, d.ephemeral, d.profiles}
-
+	// Prepare the response.
 	statusCode := d.statusCode()
 	instState := api.Instance{
 		ExpandedConfig:  d.expandedConfig,
@@ -3593,7 +3589,7 @@ func (d *lxc) Render(options ...func(response any) error) (any, any, error) {
 		}
 	}
 
-	return &instState, etag, nil
+	return &instState, d.ETag(), nil
 }
 
 // RenderFull renders the full state of the instance.

internal/server/instance/drivers/driver_qemu.go

@@ -7865,9 +7865,7 @@ func (d *qemu) Render(options ...func(response any) error) (any, any, error) {
 	}
 
 	if d.IsSnapshot() {
-		// Prepare the ETag
-		etag := []any{d.expiryDate}
-
+		// Prepare the response.
 		snapState := api.InstanceSnapshot{
 			CreatedAt:       d.creationDate,
 			ExpandedConfig:  d.expandedConfig,
@@ -7892,13 +7890,11 @@ func (d *qemu) Render(options ...func(response any) error) (any, any, error) {
 			}
 		}
 
-		return &snapState, etag, nil
+		return &snapState, d.ETag(), nil
 	}
 
-	// Prepare the ETag
-	etag := []any{d.architecture, d.localConfig, d.localDevices, d.ephemeral, d.profiles}
+	// Prepare the response.
 	statusCode := d.statusCode()
-
 	instState := api.Instance{
 		ExpandedConfig:  d.expandedConfig,
 		ExpandedDevices: d.expandedDevices.CloneNative(),
@@ -7927,7 +7923,7 @@ func (d *qemu) Render(options ...func(response any) error) (any, any, error) {
 		}
 	}
 
-	return &instState, etag, nil
+	return &instState, d.ETag(), nil
 }
 
 // RenderFull returns all info about the instance.

internal/server/instance/instance_interface.go

@@ -143,6 +143,8 @@ type Instance interface {
 	ExpiryDate() time.Time
 	FillNetworkDevice(name string, m deviceConfig.Device) (deviceConfig.Device, error)
 
+	ETag() []any
+
 	// Paths.
 	Path() string
 	ExecOutputPath() string