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Adding drives builder
Adds a drives builder to help users with building a series of drives without needing to know the intricate details of firecracker's API.
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+284
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‎drives.go

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package firecracker
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import (
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"strconv"
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models "github.com/firecracker-microvm/firecracker-go-sdk/client/models"
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)
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const rootDriveName = "root-drive"
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// DrivesBuilder is a builder that will build an array of drives used to set up
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// the firecracker microVM. The DriveID will be an incrementing number starting
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// at one
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type DrivesBuilder struct {
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rootDrive models.Drive
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drives []models.Drive
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}
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// NewDrivesBuilder will return a new DrivesBuilder with a given rootfs.
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func NewDrivesBuilder(rootDrivePath string) DrivesBuilder {
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return DrivesBuilder{}.WithRootDrive(rootDrivePath)
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}
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// DriveOpt represents an optional function used to allow for specific
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// customization of the models.Drive structure.
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type DriveOpt func(*models.Drive)
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// WithRootDrive will set the given builder with the a new root path. The root
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// drive will be set to read and write by default.
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func (b DrivesBuilder) WithRootDrive(rootDrivePath string, opts ...DriveOpt) DrivesBuilder {
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b.rootDrive = models.Drive{
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DriveID: String(rootDriveName),
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PathOnHost: &rootDrivePath,
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IsRootDevice: Bool(true),
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IsReadOnly: Bool(false),
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}
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for _, opt := range opts {
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opt(&b.rootDrive)
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}
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return b
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}
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// AddDrive will add a new drive to the given builder.
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func (b DrivesBuilder) AddDrive(path string, readOnly bool, opts ...DriveOpt) DrivesBuilder {
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drive := models.Drive{
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DriveID: String(strconv.Itoa(len(b.drives))),
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PathOnHost: &path,
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IsRootDevice: Bool(false),
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IsReadOnly: &readOnly,
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}
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for _, opt := range opts {
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opt(&drive)
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}
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b.drives = append(b.drives, drive)
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return b
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}
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// Build will construct an array of drives with the root drive at the very end.
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func (b DrivesBuilder) Build() []models.Drive {
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return append(b.drives, b.rootDrive)
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}

‎drives_test.go

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package firecracker
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import (
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"reflect"
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"testing"
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models "github.com/firecracker-microvm/firecracker-go-sdk/client/models"
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)
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func TestDrivesBuilder(t *testing.T) {
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expectedPath := "/path/to/rootfs"
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expectedDrives := []models.Drive{
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{
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DriveID: String(rootDriveName),
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PathOnHost: &expectedPath,
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IsRootDevice: Bool(true),
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IsReadOnly: Bool(false),
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},
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}
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drives := NewDrivesBuilder(expectedPath).Build()
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if e, a := expectedDrives, drives; !reflect.DeepEqual(e, a) {
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t.Errorf("expected drives %v, but received %v", e, a)
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}
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}
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func TestDrivesBuilderWithRootDrive(t *testing.T) {
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expectedPath := "/path/to/rootfs"
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expectedDrives := []models.Drive{
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{
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DriveID: String("foo"),
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PathOnHost: &expectedPath,
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IsRootDevice: Bool(true),
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IsReadOnly: Bool(false),
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},
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}
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b := NewDrivesBuilder(expectedPath)
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drives := b.WithRootDrive(expectedPath, func(drive *models.Drive) {
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drive.DriveID = String("foo")
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}).Build()
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if e, a := expectedDrives, drives; !reflect.DeepEqual(e, a) {
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t.Errorf("expected drives %v, but received %v", e, a)
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}
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}
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func TestDrivesBuilderAddDrive(t *testing.T) {
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rootPath := "/root/path"
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drivesToAdd := []struct {
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Path string
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ReadOnly bool
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Opt func(drive *models.Drive)
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}{
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{
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Path: "/2",
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ReadOnly: true,
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},
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{
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Path: "/3",
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ReadOnly: false,
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},
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{
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Path: "/4",
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ReadOnly: false,
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Opt: func(drive *models.Drive) {
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drive.Partuuid = "uuid"
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},
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},
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}
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expectedDrives := []models.Drive{
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{
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DriveID: String("0"),
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PathOnHost: String("/2"),
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IsRootDevice: Bool(false),
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IsReadOnly: Bool(true),
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},
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{
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DriveID: String("1"),
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PathOnHost: String("/3"),
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IsRootDevice: Bool(false),
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IsReadOnly: Bool(false),
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},
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{
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DriveID: String("2"),
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PathOnHost: String("/4"),
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IsRootDevice: Bool(false),
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IsReadOnly: Bool(false),
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Partuuid: "uuid",
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},
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{
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DriveID: String(rootDriveName),
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PathOnHost: &rootPath,
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IsRootDevice: Bool(true),
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IsReadOnly: Bool(false),
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},
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}
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b := NewDrivesBuilder(rootPath)
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for _, drive := range drivesToAdd {
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if drive.Opt != nil {
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b = b.AddDrive(drive.Path, drive.ReadOnly, drive.Opt)
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} else {
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b = b.AddDrive(drive.Path, drive.ReadOnly)
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}
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}
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drives := b.Build()
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if e, a := expectedDrives, drives; !reflect.DeepEqual(e, a) {
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t.Errorf("expected drives %v, but received %v", e, a)
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}
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}

‎example_test.go

Lines changed: 92 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -14,14 +14,7 @@ func ExampleWithProcessRunner_logging() {
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cfg := firecracker.Config{
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SocketPath: socketPath,
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KernelImagePath: "/path/to/kernel",
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Drives: []models.Drive{
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models.Drive{
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DriveID: firecracker.String("1"),
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IsRootDevice: firecracker.Bool(true),
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IsReadOnly: firecracker.Bool(false),
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PathOnHost: firecracker.String("/path/to/root/drive"),
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},
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},
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Drives: firecracker.NewDrivesBuilder("/path/to/rootfs").Build(),
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MachineCfg: models.MachineConfiguration{
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VcpuCount: 1,
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},
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panic(err)
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}
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}
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func ExampleDrivesBuilder() {
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drivesParams := []struct {
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Path string
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ReadOnly bool
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}{
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{
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Path: "/first/path/drive.img",
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ReadOnly: true,
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},
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{
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Path: "/second/path/drive.img",
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ReadOnly: false,
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},
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}
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// construct a new builder with the given rootfs path
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b := firecracker.NewDrivesBuilder("/path/to/rootfs")
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for _, param := range drivesParams {
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// add our additional drives
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b = b.AddDrive(param.Path, param.ReadOnly)
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}
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const socketPath = "/tmp/firecracker.sock"
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cfg := firecracker.Config{
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SocketPath: socketPath,
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KernelImagePath: "/path/to/kernel",
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// build our drives into the machine's configuration
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Drives: b.Build(),
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MachineCfg: models.MachineConfiguration{
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VcpuCount: 1,
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},
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}
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ctx := context.Background()
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m, err := firecracker.NewMachine(ctx, cfg)
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if err != nil {
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panic(fmt.Errorf("failed to create new machine: %v", err))
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}
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if err := m.Start(ctx); err != nil {
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panic(fmt.Errorf("failed to initialize machine: %v", err))
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}
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// wait for VMM to execute
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if err := m.Wait(ctx); err != nil {
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panic(err)
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}
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}
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func ExampleDrivesBuilder_DriveOpt() {
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drives := firecracker.NewDrivesBuilder("/path/to/rootfs").
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AddDrive("/path/to/drive1.img", true).
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AddDrive("/path/to/drive2.img", false, func(drive *models.Drive) {
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// set our custom bandwidth rate limiter
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drive.RateLimiter = &models.RateLimiter{
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Bandwidth: &models.TokenBucket{
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OneTimeBurst: firecracker.Int64(1024 * 1024),
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RefillTime: firecracker.Int64(500),
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Size: firecracker.Int64(1024 * 1024),
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},
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}
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}).
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Build()
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const socketPath = "/tmp/firecracker.sock"
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cfg := firecracker.Config{
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SocketPath: socketPath,
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KernelImagePath: "/path/to/kernel",
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// build our drives into the machine's configuration
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Drives: drives,
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MachineCfg: models.MachineConfiguration{
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VcpuCount: 1,
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},
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}
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ctx := context.Background()
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m, err := firecracker.NewMachine(ctx, cfg)
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if err != nil {
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panic(fmt.Errorf("failed to create new machine: %v", err))
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}
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if err := m.Start(ctx); err != nil {
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panic(fmt.Errorf("failed to initialize machine: %v", err))
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}
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// wait for VMM to execute
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if err := m.Wait(ctx); err != nil {
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panic(err)
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}
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}

‎pointer_helpers.go

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@@ -29,3 +29,18 @@ func StringValue(str *string) string {
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func String(str string) *string {
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return &str
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}
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// Int64 will return a pointer value of the given parameter.
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func Int64(v int64) *int64 {
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return &v
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}
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// Int64Value will return an int64 value. If the pointer is nil, then zero will
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// be returned.
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func Int64Value(v *int64) int64 {
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if v == nil {
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return 0
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}
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return *v
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}

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