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feat(vm): replace Firecracker with Cloud Hypervisor

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Migrate the entire VM layer from Firecracker to Cloud Hypervisor (CH).
CH provides native snapshot/restore via its HTTP API, eliminating the
need for custom UFFD handling, memfile processing, and snapshot header
management that Firecracker required.

Key changes:
- Remove fc.go, jailer.go (FC process management)
- Remove internal/uffd/ package (userfaultfd lazy page loading)
- Remove snapshot/header.go, mapping.go, memfile.go (FC snapshot format)
- Add ch.go (CH HTTP API client over Unix socket)
- Add process.go (CH process lifecycle with unshare+netns)
- Add chversion.go (CH version detection)
- Refactor sandbox manager: remove UFFD socket tracking, snapshot
  parent/diff chaining, FC-specific balloon logic; add crash watcher
- Simplify snapshot/local.go to CH's native snapshot format
- Update VM config: FirecrackerBin → VMMBin, new CH-specific fields
- Update envdclient, devicemapper, network for CH compatibility
This commit is contained in:
Rafeed M. Bhuiyan
2026-05-17 01:33:12 +06:00
parent c2dc382787
commit eaa6b8576d
25 changed files with 754 additions and 2267 deletions
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40
internal/devicemapper/devicemapper.go
View File

@ -80,8 +80,8 @@ func (r *LoopRegistry) Release(imagePath string) {
e.refcount--
if e.refcount <= 0 {
if err := losetupDetach(e.device); err != nil {
slog.Warn("losetup detach failed", "device", e.device, "error", err)
if err := losetupDetachRetry(e.device); err != nil {
slog.Error("losetup detach failed, loop device leaked", "device", e.device, "image", imagePath, "error", err)
}
delete(r.entries, imagePath)
slog.Info("loop device released", "image", imagePath, "device", e.device)
@ -94,8 +94,8 @@ func (r *LoopRegistry) ReleaseAll() {
defer r.mu.Unlock()
for path, e := range r.entries {
if err := losetupDetach(e.device); err != nil {
slog.Warn("losetup detach failed", "device", e.device, "error", err)
if err := losetupDetachRetry(e.device); err != nil {
slog.Error("losetup detach failed during shutdown", "device", e.device, "image", path, "error", err)
}
delete(r.entries, path)
}
@ -134,8 +134,8 @@ func CreateSnapshot(name, originLoopDev, cowPath string, originSizeBytes, cowSiz
// space to store all modified blocks (it's sparse, so 20GB costs nothing).
sectors := originSizeBytes / 512
if err := dmsetupCreate(name, originLoopDev, cowLoopDev, sectors); err != nil {
if detachErr := losetupDetach(cowLoopDev); detachErr != nil {
slog.Warn("cow losetup detach failed during cleanup", "device", cowLoopDev, "error", detachErr)
if detachErr := losetupDetachRetry(cowLoopDev); detachErr != nil {
slog.Error("cow losetup detach failed during cleanup, loop device leaked", "device", cowLoopDev, "error", detachErr)
}
os.Remove(cowPath)
return nil, fmt.Errorf("dmsetup create: %w", err)
@ -178,8 +178,8 @@ func RestoreSnapshot(ctx context.Context, name, originLoopDev, cowPath string, o
sectors := originSizeBytes / 512
if err := dmsetupCreate(name, originLoopDev, cowLoopDev, sectors); err != nil {
if detachErr := losetupDetach(cowLoopDev); detachErr != nil {
slog.Warn("cow losetup detach failed during cleanup", "device", cowLoopDev, "error", detachErr)
if detachErr := losetupDetachRetry(cowLoopDev); detachErr != nil {
slog.Error("cow losetup detach failed during cleanup, loop device leaked", "device", cowLoopDev, "error", detachErr)
}
return nil, fmt.Errorf("dmsetup create: %w", err)
}
@ -208,8 +208,8 @@ func RemoveSnapshot(ctx context.Context, dev *SnapshotDevice) error {
return fmt.Errorf("dmsetup remove %s: %w", dev.Name, err)
}
if err := losetupDetach(dev.CowLoopDev); err != nil {
slog.Warn("cow losetup detach failed", "device", dev.CowLoopDev, "error", err)
if err := losetupDetachRetry(dev.CowLoopDev); err != nil {
return fmt.Errorf("detach cow loop %s: %w", dev.CowLoopDev, err)
}
slog.Info("dm-snapshot removed", "name", dev.Name)
@ -297,6 +297,24 @@ func losetupDetach(dev string) error {
return exec.Command("losetup", "-d", dev).Run()
}
// losetupDetachRetry detaches a loop device with retries for transient
// "device busy" errors (kernel may still hold references briefly after
// dm-snapshot removal).
func losetupDetachRetry(dev string) error {
var lastErr error
for attempt := range 5 {
if attempt > 0 {
time.Sleep(200 * time.Millisecond)
}
if err := losetupDetach(dev); err == nil {
return nil
} else {
lastErr = err
}
}
return fmt.Errorf("after 5 attempts: %w", lastErr)
}
// dmsetupCreate creates a dm-snapshot device with persistent metadata.
func dmsetupCreate(name, originDev, cowDev string, sectors int64) error {
// Table format: <start> <size> snapshot <origin> <cow> P <chunk_size>
@ -316,7 +334,7 @@ func dmDeviceExists(name string) bool {
// dmsetupRemove removes a device-mapper device, retrying on transient
// "device busy" errors that occur when the kernel hasn't fully released
// the device after a Firecracker process exits.
// the device after a VMM process exits.
func dmsetupRemove(ctx context.Context, name string) error {
var lastErr error
for attempt := range 5 {