feat: copy rootfs when creating new VM

Author: angristan

README.md

@@ -161,3 +161,7 @@ Our C program has been successfully compiled and executed!
   "stdout": "Hello, World!"
 }
 ```
+
+## Known issues
+
+Cleanup when shutting down VMs does not work properly.

go.mod

@@ -19,6 +19,7 @@ require (
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/imroc/req v0.3.0
 	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/rs/xid v1.3.0 // indirect
 	github.com/sirupsen/logrus v1.8.1
 	github.com/streadway/amqp v1.0.0
 	github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f // indirect

go.sum

@@ -276,6 +276,8 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/rogpeppe/go-internal v1.1.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.2.2/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
+github.com/rs/xid v1.3.0 h1:6NjYksEUlhurdVehpc7S7dk6DAmcKv8V9gG0FsVN2U4=
+github.com/rs/xid v1.3.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
 github.com/safchain/ethtool v0.0.0-20190326074333-42ed695e3de8/go.mod h1:Z0q5wiBQGYcxhMZ6gUqHn6pYNLypFAvaL3UvgZLR0U4=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/sirupsen/logrus v1.0.6/go.mod h1:pMByvHTf9Beacp5x1UXfOR9xyW/9antXMhjMPG0dEzc=

job.go

@@ -53,7 +53,6 @@ func (job benchJob) run(ctx context.Context, WarmVMs <-chan runningFirecracker)
 	var httpRes *http.Response
 	var agentRes agentExecRes
 
-	// FIXME
 	httpRes, err = http.Post("http://"+vm.ip.String()+":8080/run", "application/json", bytes.NewBuffer(reqJSON))
 	if err != nil {
 		log.WithError(err).Error("Failed to request execution to agent")
@@ -76,5 +75,4 @@ func (job benchJob) run(ctx context.Context, WarmVMs <-chan runningFirecracker)
 	if err != nil {
 		q.setjobFailed(ctx, job, agentExecRes{Error: err.Error()})
 	}
-
 }

main.go

@@ -47,6 +47,7 @@ type agentExecRes struct {
 type runningFirecracker struct {
 	vmmCtx    context.Context
 	vmmCancel context.CancelFunc
+	vmmID     string
 	machine   *firecracker.Machine
 	ip        net.IP
 }

options.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"fmt"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -12,17 +11,16 @@ import (
 	models "github.com/firecracker-microvm/firecracker-go-sdk/client/models"
 )
 
-// Converts options to a usable firecracker config
-func getFirecrackerConfig() (firecracker.Config, error) {
-	socket := getSocketPath()
+func getFirecrackerConfig(vmmID string) (firecracker.Config, error) {
+	socket := getSocketPath(vmmID)
 	return firecracker.Config{
 		SocketPath:      socket,
 		KernelImagePath: "../../linux/vmlinux",
 		LogPath:         fmt.Sprintf("%s.log", socket),
 		Drives: []models.Drive{{
 			DriveID: firecracker.String("1"),
 			// TODO: copy base rootfs and use a temp roots per VM
-			PathOnHost:   firecracker.String("../agent/rootfs.ext4"),
+			PathOnHost:   firecracker.String("/tmp/rootfs-" + vmmID + ".ext4"),
 			IsRootDevice: firecracker.Bool(true),
 			IsReadOnly:   firecracker.Bool(false),
 			RateLimiter: firecracker.NewRateLimiter(
@@ -54,11 +52,12 @@ func getFirecrackerConfig() (firecracker.Config, error) {
 	}, nil
 }
 
-func getSocketPath() string {
+func getSocketPath(vmmID string) string {
 	filename := strings.Join([]string{
 		".firecracker.sock",
 		strconv.Itoa(os.Getpid()),
-		strconv.Itoa(rand.Intn(10000))},
+		vmmID,
+	},
 		"-",
 	)
 	dir := os.TempDir()

vm.go

@@ -46,4 +46,8 @@ func (vm runningFirecracker) shutDown() {
 	if err != nil {
 		log.WithError(err).Error("Failed to delete firecracker socket")
 	}
+	err = os.Remove("/tmp/rootfs-" + vm.vmmID + ".ext4")
+	if err != nil {
+		log.WithError(err).Error("Failed to delete firecracker rootfs")
+	}
 }

vmm.go

@@ -3,16 +3,31 @@ package main
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
 
 	firecracker "github.com/firecracker-microvm/firecracker-go-sdk"
+	"github.com/rs/xid"
 	log "github.com/sirupsen/logrus"
 )
 
+func copy(src string, dst string) error {
+	data, err := ioutil.ReadFile(src)
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(dst, data, 0644)
+	return err
+}
+
 // Create a VMM with a given set of options and start the VM
 func createAndStartVM(ctx context.Context) (*runningFirecracker, error) {
-	fcCfg, err := getFirecrackerConfig()
+	vmmID := xid.New().String()
+
+	copy("../agent/rootfs.ext4", "/tmp/rootfs-"+vmmID+".ext4")
+
+	fcCfg, err := getFirecrackerConfig(vmmID)
 	if err != nil {
 		log.Errorf("Error: %s", err)
 		return nil, err
@@ -78,6 +93,7 @@ func createAndStartVM(ctx context.Context) (*runningFirecracker, error) {
 	return &runningFirecracker{
 		vmmCtx:    vmmCtx,
 		vmmCancel: vmmCancel,
+		vmmID:     vmmID,
 		machine:   m,
 		ip:        m.Cfg.NetworkInterfaces[0].StaticConfiguration.IPConfiguration.IPAddr.IP,
 	}, nil