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forked from wrenn/wrenn

feat(vm): replace Firecracker with Cloud Hypervisor

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:
2026-05-17 01:33:12 +06:00
parent c2dc382787
commit eaa6b8576d
25 changed files with 754 additions and 2267 deletions

213
internal/vm/ch.go Normal file
View File

@ -0,0 +1,213 @@
package vm
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"net"
"net/http"
)
// chClient talks to the Cloud Hypervisor HTTP API over a Unix socket.
type chClient struct {
http *http.Client
socketPath string
}
func newCHClient(socketPath string) *chClient {
return &chClient{
socketPath: socketPath,
http: &http.Client{
Transport: &http.Transport{
DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
var d net.Dialer
return d.DialContext(ctx, "unix", socketPath)
},
},
},
}
}
func (c *chClient) do(ctx context.Context, method, path string, body any) error {
var bodyReader io.Reader
if body != nil {
data, err := json.Marshal(body)
if err != nil {
return fmt.Errorf("marshal request body: %w", err)
}
bodyReader = bytes.NewReader(data)
}
req, err := http.NewRequestWithContext(ctx, method, "http://localhost"+path, bodyReader)
if err != nil {
return fmt.Errorf("create request: %w", err)
}
if body != nil {
req.Header.Set("Content-Type", "application/json")
}
resp, err := c.http.Do(req)
if err != nil {
return fmt.Errorf("%s %s: %w", method, path, err)
}
defer resp.Body.Close()
if resp.StatusCode >= 300 {
respBody, _ := io.ReadAll(resp.Body)
return fmt.Errorf("%s %s: status %d: %s", method, path, resp.StatusCode, string(respBody))
}
return nil
}
// --- CH API payload types ---
type chPayload struct {
Firmware string `json:"firmware,omitempty"`
Kernel string `json:"kernel"`
Cmdline string `json:"cmdline"`
}
type chCPUs struct {
BootVCPUs int `json:"boot_vcpus"`
MaxVCPUs int `json:"max_vcpus"`
}
type chMemory struct {
Size uint64 `json:"size"`
Shared bool `json:"shared,omitempty"`
HotplugSize uint64 `json:"hotplug_size,omitempty"`
HotplugMethod string `json:"hotplug_method,omitempty"`
}
type chDisk struct {
Path string `json:"path"`
Readonly bool `json:"readonly,omitempty"`
ImageType string `json:"image_type,omitempty"`
}
type chNet struct {
Tap string `json:"tap"`
MAC string `json:"mac"`
NumQs int `json:"num_queues,omitempty"`
QueueS int `json:"queue_size,omitempty"`
}
type chBalloon struct {
Size int64 `json:"size"`
DeflateOnOOM bool `json:"deflate_on_oom"`
FreePageRep bool `json:"free_page_reporting,omitempty"`
}
type chConsole struct {
Mode string `json:"mode"`
}
type chCreatePayload struct {
Payload chPayload `json:"payload"`
CPUs chCPUs `json:"cpus"`
Memory chMemory `json:"memory"`
Disks []chDisk `json:"disks"`
Net []chNet `json:"net"`
Balloon *chBalloon `json:"balloon,omitempty"`
Serial chConsole `json:"serial"`
Console chConsole `json:"console"`
}
// createVM sends the full VM configuration as a single payload.
func (c *chClient) createVM(ctx context.Context, cfg *VMConfig) error {
memBytes := uint64(cfg.MemoryMB) * 1024 * 1024
payload := chCreatePayload{
Payload: chPayload{
Kernel: cfg.KernelPath,
Cmdline: cfg.kernelArgs(),
},
CPUs: chCPUs{
BootVCPUs: cfg.VCPUs,
MaxVCPUs: cfg.VCPUs,
},
Memory: chMemory{
Size: memBytes,
Shared: true,
},
Disks: []chDisk{
{
Path: cfg.SandboxDir + "/rootfs.ext4",
ImageType: "Raw",
},
},
Net: []chNet{
{
Tap: cfg.TapDevice,
MAC: cfg.TapMAC,
},
},
Balloon: &chBalloon{
Size: 0,
DeflateOnOOM: true,
FreePageRep: true,
},
Serial: chConsole{
Mode: "Tty",
},
Console: chConsole{
Mode: "Off",
},
}
return c.do(ctx, http.MethodPut, "/api/v1/vm.create", payload)
}
// bootVM starts the VM after creation.
func (c *chClient) bootVM(ctx context.Context) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.boot", nil)
}
// pauseVM pauses the microVM.
func (c *chClient) pauseVM(ctx context.Context) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.pause", nil)
}
// resumeVM resumes a paused microVM.
func (c *chClient) resumeVM(ctx context.Context) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.resume", nil)
}
// snapshotVM creates a VM snapshot to the given directory.
func (c *chClient) snapshotVM(ctx context.Context, destURL string) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.snapshot", map[string]string{
"destination_url": destURL,
})
}
// restoreVM restores a VM from a snapshot via the API. Uses OnDemand memory
// restore mode for UFFD-based lazy page loading — only pages the guest
// actually touches are faulted in from disk.
func (c *chClient) restoreVM(ctx context.Context, sourceURL string) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.restore", map[string]any{
"source_url": sourceURL,
"memory_restore_mode": "OnDemand",
"resume": true,
})
}
// shutdownVMM cleanly shuts down the Cloud Hypervisor VMM process.
func (c *chClient) shutdownVMM(ctx context.Context) error {
return c.do(ctx, http.MethodPut, "/api/v1/vmm.shutdown", nil)
}
// resizeBalloon adjusts the balloon target at runtime.
// sizeBytes is memory to take FROM the guest (0 = give all back).
func (c *chClient) resizeBalloon(ctx context.Context, sizeBytes int64) error {
return c.do(ctx, http.MethodPut, "/api/v1/vm.resize", map[string]int64{
"desired_balloon": sizeBytes,
})
}
// ping checks if the VMM is alive and ready to accept commands.
func (c *chClient) ping(ctx context.Context) error {
return c.do(ctx, http.MethodGet, "/api/v1/vmm.ping", nil)
}