// +build windows
// Maintainer: jhowardmsft
// Locale: en-gb
// About: Graph-driver for Linux Containers On Windows (LCOW)
//
// This graphdriver runs in two modes. Yet to be determined which one will
// be the shipping mode. The global mode is where a single utility VM
// is used for all service VM tool operations. This isn't safe security-wise
// as it's attaching a sandbox of multiple containers to it, containing
// untrusted data. This may be fine for client devops scenarios. In
// safe mode, a unique utility VM is instantiated for all service VM tool
// operations. The downside of safe-mode is that operations are slower as
// a new service utility VM has to be started and torn-down when needed.
//
// Options (needs official documentation, but lets get full functionality first...) @jhowardmsft
//
// The following options are read by the graphdriver itself:
//
// * lcow.globalmode - Enables global service VM Mode
// -- Possible values: true/false
// -- Default if omitted: false
//
// * lcow.sandboxsize - Specifies a custom sandbox size in GB for starting a container
// -- Possible values: >= default sandbox size (opengcs defined, currently 20)
// -- Default if omitted: 20
//
// The following options are read by opengcs:
//
// * lcow.kirdpath - Specifies a custom path to a kernel/initrd pair
// -- Possible values: Any local path that is not a mapped drive
// -- Default if omitted: %ProgramFiles%\Linux Containers
//
// * lcow.kernel - Specifies a custom kernel file located in the `lcow.kirdpath` path
// -- Possible values: Any valid filename
// -- Default if omitted: bootx64.efi
//
// * lcow.initrd - Specifies a custom initrd file located in the `lcow.kirdpath` path
// -- Possible values: Any valid filename
// -- Default if omitted: initrd.img
//
// * lcow.bootparameters - Specifies additional boot parameters for booting in kernel+initrd mode
// -- Possible values: Any valid linux kernel boot options
// -- Default if omitted: <nil>
//
// * lcow.vhdx - Specifies a custom vhdx file to boot (instead of a kernel+initrd)
// -- Possible values: Any valid filename
// -- Default if omitted: uvm.vhdx under `lcow.kirdpath`
//
// * lcow.timeout - Specifies a timeout for utility VM operations in seconds
// -- Possible values: >=0
// -- Default if omitted: 300
// TODO: Grab logs from SVM at terminate or errors
package lcow
import (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"syscall"
"time"
"github.com/Microsoft/hcsshim"
"github.com/Microsoft/opengcs/client"
"github.com/docker/docker/daemon/graphdriver"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/containerfs"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/pkg/ioutils"
"github.com/docker/docker/pkg/system"
"github.com/sirupsen/logrus"
)
// init registers this driver to the register. It gets initialised by the
// function passed in the second parameter, implemented in this file.
func init() {
graphdriver.Register("lcow", InitDriver)
}
const (
// sandboxFilename is the name of the file containing a layer's sandbox (read-write layer).
sandboxFilename = "sandbox.vhdx"
// scratchFilename is the name of the scratch-space used by an SVM to avoid running out of memory.
scratchFilename = "scratch.vhdx"
// layerFilename is the name of the file containing a layer's read-only contents.
// Note this really is VHD format, not VHDX.
layerFilename = "layer.vhd"
// toolsScratchPath is a location in a service utility VM that the tools can use as a
// scratch space to avoid running out of memory.
toolsScratchPath = "/tmp/scratch"
// svmGlobalID is the ID used in the serviceVMs map for the global service VM when running in "global" mode.
svmGlobalID = "_lcow_global_svm_"
// cacheDirectory is the sub-folder under the driver's data-root used to cache blank sandbox and scratch VHDs.
cacheDirectory = "cache"
// scratchDirectory is the sub-folder under the driver's data-root used for scratch VHDs in service VMs
scratchDirectory = "scratch"
// errOperationPending is the HRESULT returned by the HCS when the VM termination operation is still pending.
errOperationPending syscall.Errno = 0xc0370103
)
// Driver represents an LCOW graph driver.
type Driver struct {
dataRoot string // Root path on the host where we are storing everything.
cachedSandboxFile string // Location of the local default-sized cached sandbox.
cachedSandboxMutex sync.Mutex // Protects race conditions from multiple threads creating the cached sandbox.
cachedScratchFile string // Location of the local cached empty scratch space.
cachedScratchMutex sync.Mutex // Protects race conditions from multiple threads creating the cached scratch.
options []string // Graphdriver options we are initialised with.
globalMode bool // Indicates if running in an unsafe/global service VM mode.
// NOTE: It is OK to use a cache here because Windows does not support
// restoring containers when the daemon dies.
serviceVms *serviceVMMap // Map of the configs representing the service VM(s) we are running.
}
// layerDetails is the structure returned by a helper function `getLayerDetails`
// for getting information about a layer folder
type layerDetails struct {
filename string // \path\to\sandbox.vhdx or \path\to\layer.vhd
size int64 // size of the above file
isSandbox bool // true if sandbox.vhdx
}
// deletefiles is a helper function for initialisation where we delete any
// left-over scratch files in case we were previously forcibly terminated.
func deletefiles(path string, f os.FileInfo, err error) error {
if strings.HasSuffix(f.Name(), ".vhdx") {
logrus.Warnf("lcowdriver: init: deleting stale scratch file %s", path)
return os.Remove(path)
}
return nil
}
// InitDriver returns a new LCOW storage driver.
func InitDriver(dataRoot string, options []string, _, _ []idtools.IDMap) (graphdriver.Driver, error) {
title := "lcowdriver: init:"
cd := filepath.Join(dataRoot, cacheDirectory)
sd := filepath.Join(dataRoot, scratchDirectory)
d := &Driver{
dataRoot: dataRoot,
options: options,
cachedSandboxFile: filepath.Join(cd, sandboxFilename),
cachedScratchFile: filepath.Join(cd, scratchFilename),
serviceVms: &serviceVMMap{
svms: make(map[string]*serviceVMMapItem),
},
globalMode: false,
}
// Looks for relevant options
for _, v := range options {
opt := strings.SplitN(v, "=", 2)
if len(opt) == 2 {
switch strings.ToLower(opt[0]) {
case "lcow.globalmode":
var err error
d.globalMode, err = strconv.ParseBool(opt[1])
if err != nil {
return nil, fmt.Errorf("%s failed to parse value for 'lcow.globalmode' - must be 'true' or 'false'", title)
}
break
}
}
}
// Make sure the dataRoot directory is created
if err := idtools.MkdirAllAs(dataRoot, 0700, 0, 0); err != nil {
return nil, fmt.Errorf("%s failed to create '%s': %v", title, dataRoot, err)
}
// Make sure the cache directory is created under dataRoot
if err := idtools.MkdirAllAs(cd, 0700, 0, 0); err != nil {
return nil, fmt.Errorf("%s failed to create '%s': %v", title, cd, err)
}
// Make sure the scratch directory is created under dataRoot
if err := idtools.MkdirAllAs(sd, 0700, 0, 0); err != nil {
return nil, fmt.Errorf("%s failed to create '%s': %v", title, sd, err)
}
// Delete any items in the scratch directory
filepath.Walk(sd, deletefiles)
logrus.Infof("%s dataRoot: %s globalMode: %t", title, dataRoot, d.globalMode)
return d, nil
}
func (d *Driver) getVMID(id string) string {
if d.globalMode {
return svmGlobalID
}
return id
}
// startServiceVMIfNotRunning starts a service utility VM if it is not currently running.
// It can optionally be started with a mapped virtual disk. Returns a opengcs config structure
// representing the VM.
func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.MappedVirtualDisk, context string) (_ *serviceVM, err error) {
// Use the global ID if in global mode
id = d.getVMID(id)
title := fmt.Sprintf("lcowdriver: startservicevmifnotrunning %s:", id)
// Attempt to add ID to the service vm map
logrus.Debugf("%s: Adding entry to service vm map", title)
svm, exists, err := d.serviceVms.add(id)
if err != nil && err == errVMisTerminating {
// VM is in the process of terminating. Wait until it's done and and then try again
logrus.Debugf("%s: VM with current ID still in the process of terminating: %s", title, id)
if err := svm.getStopError(); err != nil {
logrus.Debugf("%s: VM %s did not stop succesfully: %s", title, id, err)
return nil, err
}
return d.startServiceVMIfNotRunning(id, mvdToAdd, context)
} else if err != nil {
logrus.Debugf("%s: failed to add service vm to map: %s", err)
return nil, fmt.Errorf("%s: failed to add to service vm map: %s", title, err)
}
if exists {
// Service VM is already up and running. In this case, just hot add the vhds.
logrus.Debugf("%s: service vm already exists. Just hot adding: %+v", title, mvdToAdd)
if err := svm.hotAddVHDs(mvdToAdd...); err != nil {
logrus.Debugf("%s: failed to hot add vhds on service vm creation: %s", title, err)
return nil, fmt.Errorf("%s: failed to hot add vhds on service vm: %s", title, err)
}
return svm, nil
}
// We are the first service for this id, so we need to start it
logrus.Debugf("%s: service vm doesn't exist. Now starting it up: %s", title, id)
defer func() {
// Signal that start has finished, passing in the error if any.
svm.signalStartFinished(err)
if err != nil {
// We added a ref to the VM, since we failed, we should delete the ref.
d.terminateServiceVM(id, "error path on startServiceVMIfNotRunning", false)
}
}()
// Generate a default configuration
if err := svm.config.GenerateDefault(d.options); err != nil {
return nil, fmt.Errorf("%s failed to generate default gogcs configuration for global svm (%s): %s", title, context, err)
}
// For the name, we deliberately suffix if safe-mode to ensure that it doesn't
// clash with another utility VM which may be running for the container itself.
// This also makes it easier to correlate through Get-ComputeProcess.
if id == svmGlobalID {
svm.config.Name = svmGlobalID
} else {
svm.config.Name = fmt.Sprintf("%s_svm", id)
}
// Ensure we take the cached scratch mutex around the check to ensure the file is complete
// and not in the process of being created by another thread.
scratchTargetFile := filepath.Join(d.dataRoot, scratchDirectory, fmt.Sprintf("%s.vhdx", id))
logrus.Debugf("%s locking cachedScratchMutex", title)
d.cachedScratchMutex.Lock()
if _, err := os.Stat(d.cachedScratchFile); err == nil {
// Make a copy of cached scratch to the scratch directory
logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) cloning cached scratch for mvd", context)
if err := client.CopyFile(d.cachedScratchFile, scratchTargetFile, true); err != nil {
logrus.Debugf("%s releasing cachedScratchMutex on err: %s", title, err)
d.cachedScratchMutex.Unlock()
return nil, err
}
// Add the cached clone as a mapped virtual disk
logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) adding cloned scratch as mvd", context)
mvd := hcsshim.MappedVirtualDisk{
HostPath: scratchTargetFile,
ContainerPath: toolsScratchPath,
CreateInUtilityVM: true,
}
svm.config.MappedVirtualDisks = append(svm.config.MappedVirtualDisks, mvd)
svm.scratchAttached = true
}
logrus.Debugf("%s releasing cachedScratchMutex", title)
d.cachedScratchMutex.Unlock()
// If requested to start it with a mapped virtual disk, add it now.
svm.config.MappedVirtualDisks = append(svm.config.MappedVirtualDisks, mvdToAdd...)
for _, mvd := range svm.config.MappedVirtualDisks {
svm.attachedVHDs[mvd.HostPath] = 1
}
// Start it.
logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) starting %s", context, svm.config.Name)
if err := svm.config.StartUtilityVM(); err != nil {
return nil, fmt.Errorf("failed to start service utility VM (%s): %s", context, err)
}
// defer function to terminate the VM if the next steps fail
defer func() {
if err != nil {
waitTerminate(svm, fmt.Sprintf("startServiceVmIfNotRunning: %s (%s)", id, context))
}
}()
// Now we have a running service VM, we can create the cached scratch file if it doesn't exist.
logrus.Debugf("%s locking cachedScratchMutex", title)
d.cachedScratchMutex.Lock()
if _, err := os.Stat(d.cachedScratchFile); err != nil {
logrus.Debugf("%s (%s): creating an SVM scratch", title, context)
// Don't use svm.CreateExt4Vhdx since that only works when the service vm is setup,
// but we're still in that process right now.
if err := svm.config.CreateExt4Vhdx(scratchTargetFile, client.DefaultVhdxSizeGB, d.cachedScratchFile); err != nil {
logrus.Debugf("%s (%s): releasing cachedScratchMutex on error path", title, context)
d.cachedScratchMutex.Unlock()
logrus.Debugf("%s: failed to create vm scratch %s: %s", title, scratchTargetFile, err)
return nil, fmt.Errorf("failed to create SVM scratch VHDX (%s): %s", context, err)
}
}
logrus.Debugf("%s (%s): releasing cachedScratchMutex", title, context)
d.cachedScratchMutex.Unlock()
// Hot-add the scratch-space if not already attached
if !svm.scratchAttached {
logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) hot-adding scratch %s", context, scratchTargetFile)
if err := svm.hotAddVHDsAtStart(hcsshim.MappedVirtualDisk{
HostPath: scratchTargetFile,
ContainerPath: toolsScratchPath,
CreateInUtilityVM: true,
}); err != nil {
logrus.Debugf("%s: failed to hot-add scratch %s: %s", title, scratchTargetFile, err)
return nil, fmt.Errorf("failed to hot-add %s failed: %s", scratchTargetFile, err)
}
svm.scratchAttached = true
}
logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) success", context)
return svm, nil
}
// terminateServiceVM terminates a service utility VM if its running if it's,
// not being used by any goroutine, but does nothing when in global mode as it's
// lifetime is limited to that of the daemon. If the force flag is set, then
// the VM will be killed regardless of the ref count or if it's global.
func (d *Driver) terminateServiceVM(id, context string, force bool) (err error) {
// We don't do anything in safe mode unless the force flag has been passed, which
// is only the case for cleanup at driver termination.
if d.globalMode && !force {
logrus.Debugf("lcowdriver: terminateservicevm: %s (%s) - doing nothing as in global mode", id, context)
return nil
}
id = d.getVMID(id)
var svm *serviceVM
var lastRef bool
if !force {
// In the not force case, we ref count
svm, lastRef, err = d.serviceVms.decrementRefCount(id)
} else {
// In the force case, we ignore the ref count and just set it to 0
svm, err = d.serviceVms.setRefCountZero(id)
lastRef = true
}
if err == errVMUnknown {
return nil
} else if err == errVMisTerminating {
return svm.getStopError()
} else if !lastRef {
return nil
}
// We run the deletion of the scratch as a deferred function to at least attempt
// clean-up in case of errors.
defer func() {
if svm.scratchAttached {
scratchTargetFile := filepath.Join(d.dataRoot, scratchDirectory, fmt.Sprintf("%s.vhdx", id))
logrus.Debugf("lcowdriver: terminateservicevm: %s (%s) - deleting scratch %s", id, context, scratchTargetFile)
if errRemove := os.Remove(scratchTargetFile); errRemove != nil {
logrus.Warnf("failed to remove scratch file %s (%s): %s", scratchTargetFile, context, errRemove)
err = errRemove
}
}
// This function shouldn't actually return error unless there is a bug
if errDelete := d.serviceVms.deleteID(id); errDelete != nil {
logrus.Warnf("failed to service vm from svm map %s (%s): %s", id, context, errDelete)
}
// Signal that this VM has stopped
svm.signalStopFinished(err)
}()
// Now it's possible that the serivce VM failed to start and now we are trying to termiante it.
// In this case, we will relay the error to the goroutines waiting for this vm to stop.
if err := svm.getStartError(); err != nil {
logrus.Debugf("lcowdriver: terminateservicevm: %s had failed to start up: %s", id, err)
return err
}
if err := waitTerminate(svm, fmt.Sprintf("terminateservicevm: %s (%s)", id, context)); err != nil {
return err
}
logrus.Debugf("lcowdriver: terminateservicevm: %s (%s) - success", id, context)
return nil
}
func waitTerminate(svm *serviceVM, context string) error {
if svm.config == nil {
return fmt.Errorf("lcowdriver: waitTermiante: Nil utility VM. %s", context)
}
logrus.Debugf("lcowdriver: waitTerminate: Calling terminate: %s", context)
if err := svm.config.Uvm.Terminate(); err != nil {
// We might get operation still pending from the HCS. In that case, we shouldn't return
// an error since we call wait right after.
underlyingError := err
if conterr, ok := err.(*hcsshim.ContainerError); ok {
underlyingError = conterr.Err
}
if syscallErr, ok := underlyingError.(syscall.Errno); ok {
underlyingError = syscallErr
}
if underlyingError != errOperationPending {
return fmt.Errorf("failed to terminate utility VM (%s): %s", context, err)
}
logrus.Debugf("lcowdriver: waitTerminate: uvm.Terminate() returned operation pending (%s)", context)
}
logrus.Debugf("lcowdriver: waitTerminate: (%s) - waiting for utility VM to terminate", context)
if err := svm.config.Uvm.WaitTimeout(time.Duration(svm.config.UvmTimeoutSeconds) * time.Second); err != nil {
return fmt.Errorf("failed waiting for utility VM to terminate (%s): %s", context, err)
}
return nil
}
// String returns the string representation of a driver. This should match
// the name the graph driver has been registered with.
func (d *Driver) String() string {
return "lcow"
}
// Status returns the status of the driver.
func (d *Driver) Status() [][2]string {
return [][2]string{
{"LCOW", ""},
// TODO: Add some more info here - mode, home, ....
}
}
// Exists returns true if the given id is registered with this driver.
func (d *Driver) Exists(id string) bool {
_, err := os.Lstat(d.dir(id))
logrus.Debugf("lcowdriver: exists: id %s %t", id, err == nil)
return err == nil
}
// CreateReadWrite creates a layer that is writable for use as a container
// file system. That equates to creating a sandbox.
func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
title := fmt.Sprintf("lcowdriver: createreadwrite: id %s", id)
logrus.Debugf(title)
// First we need to create the folder
if err := d.Create(id, parent, opts); err != nil {
return err
}
// Look for an explicit sandbox size option.
sandboxSize := uint64(client.DefaultVhdxSizeGB)
for k, v := range opts.StorageOpt {
switch strings.ToLower(k) {
case "lcow.sandboxsize":
var err error
sandboxSize, err = strconv.ParseUint(v, 10, 32)
if err != nil {
return fmt.Errorf("%s failed to parse value '%s' for 'lcow.sandboxsize'", title, v)
}
if sandboxSize < client.DefaultVhdxSizeGB {
return fmt.Errorf("%s 'lcow.sandboxsize' option cannot be less than %d", title, client.DefaultVhdxSizeGB)
}
break
}
}
// Massive perf optimisation here. If we know that the RW layer is the default size,
// and that the cached sandbox already exists, and we are running in safe mode, we
// can just do a simple copy into the layers sandbox file without needing to start a
// unique service VM. For a global service VM, it doesn't really matter. Of course,
// this is only the case where the sandbox is the default size.
//
// Make sure we have the sandbox mutex taken while we are examining it.
if sandboxSize == client.DefaultVhdxSizeGB {
logrus.Debugf("%s: locking cachedSandboxMutex", title)
d.cachedSandboxMutex.Lock()
_, err := os.Stat(d.cachedSandboxFile)
logrus.Debugf("%s: releasing cachedSandboxMutex", title)
d.cachedSandboxMutex.Unlock()
if err == nil {
logrus.Debugf("%s: using cached sandbox to populate", title)
if err := client.CopyFile(d.cachedSandboxFile, filepath.Join(d.dir(id), sandboxFilename), true); err != nil {
return err
}
return nil
}
}
logrus.Debugf("%s: creating SVM to create sandbox", title)
svm, err := d.startServiceVMIfNotRunning(id, nil, "createreadwrite")
if err != nil {
return err
}
defer d.terminateServiceVM(id, "createreadwrite", false)
// So the sandbox needs creating. If default size ensure we are the only thread populating the cache.
// Non-default size we don't store, just create them one-off so no need to lock the cachedSandboxMutex.
if sandboxSize == client.DefaultVhdxSizeGB {
logrus.Debugf("%s: locking cachedSandboxMutex for creation", title)
d.cachedSandboxMutex.Lock()
defer func() {
logrus.Debugf("%s: releasing cachedSandboxMutex for creation", title)
d.cachedSandboxMutex.Unlock()
}()
}
// Make sure we don't write to our local cached copy if this is for a non-default size request.
targetCacheFile := d.cachedSandboxFile
if sandboxSize != client.DefaultVhdxSizeGB {
targetCacheFile = ""
}
// Create the ext4 vhdx
logrus.Debugf("%s: creating sandbox ext4 vhdx", title)
if err := svm.createExt4VHDX(filepath.Join(d.dir(id), sandboxFilename), uint32(sandboxSize), targetCacheFile); err != nil {
logrus.Debugf("%s: failed to create sandbox vhdx for %s: %s", title, id, err)
return err
}
return nil
}
// Create creates the folder for the layer with the given id, and
// adds it to the layer chain.
func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
logrus.Debugf("lcowdriver: create: id %s parent: %s", id, parent)
parentChain, err := d.getLayerChain(parent)
if err != nil {
return err
}
var layerChain []string
if parent != "" {
if !d.Exists(parent) {
return fmt.Errorf("lcowdriver: cannot create layer folder with missing parent %s", parent)
}
layerChain = []string{d.dir(parent)}
}
layerChain = append(layerChain, parentChain...)
// Make sure layers are created with the correct ACL so that VMs can access them.
layerPath := d.dir(id)
logrus.Debugf("lcowdriver: create: id %s: creating %s", id, layerPath)
if err := system.MkdirAllWithACL(layerPath, 755, system.SddlNtvmAdministratorsLocalSystem); err != nil {
return err
}
if err := d.setLayerChain(id, layerChain); err != nil {
if err2 := os.RemoveAll(layerPath); err2 != nil {
logrus.Warnf("failed to remove layer %s: %s", layerPath, err2)
}
return err
}
logrus.Debugf("lcowdriver: create: id %s: success", id)
return nil
}
// Remove unmounts and removes the dir information.
func (d *Driver) Remove(id string) error {
logrus.Debugf("lcowdriver: remove: id %s", id)
tmpID := fmt.Sprintf("%s-removing", id)
tmpLayerPath := d.dir(tmpID)
layerPath := d.dir(id)
logrus.Debugf("lcowdriver: remove: id %s: layerPath %s", id, layerPath)
// Unmount all the layers
err := d.Put(id)
if err != nil {
logrus.Debugf("lcowdriver: remove id %s: failed to unmount: %s", id, err)
return err
}
// for non-global case just kill the vm
if !d.globalMode {
if err := d.terminateServiceVM(id, fmt.Sprintf("Remove %s", id), true); err != nil {
return err
}
}
if err := os.Rename(layerPath, tmpLayerPath); err != nil && !os.IsNotExist(err) {
return err
}
if err := os.RemoveAll(tmpLayerPath); err != nil {
return err
}
logrus.Debugf("lcowdriver: remove: id %s: layerPath %s succeeded", id, layerPath)
return nil
}
// Get returns the rootfs path for the id. It is reference counted and
// effectively can be thought of as a "mount the layer into the utility
// vm if it isn't already". The contract from the caller of this is that
// all Gets and Puts are matched. It -should- be the case that on cleanup,
// nothing is mounted.
//
// For optimisation, we don't actually mount the filesystem (which in our
// case means [hot-]adding it to a service VM. But we track that and defer
// the actual adding to the point we need to access it.
func (d *Driver) Get(id, mountLabel string) (containerfs.ContainerFS, error) {
title := fmt.Sprintf("lcowdriver: get: %s", id)
logrus.Debugf(title)
// Generate the mounts needed for the defered operation.
disks, err := d.getAllMounts(id)
if err != nil {
logrus.Debugf("%s failed to get all layer details for %s: %s", title, d.dir(id), err)
return nil, fmt.Errorf("%s failed to get layer details for %s: %s", title, d.dir(id), err)
}
logrus.Debugf("%s: got layer mounts: %+v", title, disks)
return &lcowfs{
root: unionMountName(disks),
d: d,
mappedDisks: disks,
vmID: d.getVMID(id),
}, nil
}
// Put does the reverse of get. If there are no more references to
// the layer, it unmounts it from the utility VM.
func (d *Driver) Put(id string) error {
title := fmt.Sprintf("lcowdriver: put: %s", id)
// Get the service VM that we need to remove from
svm, err := d.serviceVms.get(d.getVMID(id))
if err == errVMUnknown {
return nil
} else if err == errVMisTerminating {
return svm.getStopError()
}
// Generate the mounts that Get() might have mounted
disks, err := d.getAllMounts(id)
if err != nil {
logrus.Debugf("%s failed to get all layer details for %s: %s", title, d.dir(id), err)
return fmt.Errorf("%s failed to get layer details for %s: %s", title, d.dir(id), err)
}
// Now, we want to perform the unmounts, hot-remove and stop the service vm.
// We want to go though all the steps even if we have an error to clean up properly
err = svm.deleteUnionMount(unionMountName(disks), disks...)
if err != nil {
logrus.Debugf("%s failed to delete union mount %s: %s", title, id, err)
}
err1 := svm.hotRemoveVHDs(disks...)
if err1 != nil {
logrus.Debugf("%s failed to hot remove vhds %s: %s", title, id, err)
if err == nil {
err = err1
}
}
err1 = d.terminateServiceVM(id, fmt.Sprintf("Put %s", id), false)
if err1 != nil {
logrus.Debugf("%s failed to terminate service vm %s: %s", title, id, err1)
if err == nil {
err = err1
}
}
logrus.Debugf("Put succeeded on id %s", id)
return err
}
// Cleanup ensures the information the driver stores is properly removed.
// We use this opportunity to cleanup any -removing folders which may be
// still left if the daemon was killed while it was removing a layer.
func (d *Driver) Cleanup() error {
title := "lcowdriver: cleanup"
items, err := ioutil.ReadDir(d.dataRoot)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
// Note we don't return an error below - it's possible the files
// are locked. However, next time around after the daemon exits,
// we likely will be able to to cleanup successfully. Instead we log
// warnings if there are errors.
for _, item := range items {
if item.IsDir() && strings.HasSuffix(item.Name(), "-removing") {
if err := os.RemoveAll(filepath.Join(d.dataRoot, item.Name())); err != nil {
logrus.Warnf("%s failed to cleanup %s: %s", title, item.Name(), err)
} else {
logrus.Infof("%s cleaned up %s", title, item.Name())
}
}
}
// Cleanup any service VMs we have running, along with their scratch spaces.
// We don't take the lock for this as it's taken in terminateServiceVm.
for k, v := range d.serviceVms.svms {
logrus.Debugf("%s svm entry: %s: %+v", title, k, v)
d.terminateServiceVM(k, "cleanup", true)
}
return nil
}
// Diff takes a layer (and it's parent layer which may be null, but
// is ignored by this implementation below) and returns a reader for
// a tarstream representing the layers contents. The id could be
// a read-only "layer.vhd" or a read-write "sandbox.vhdx". The semantics
// of this function dictate that the layer is already mounted.
// However, as we do lazy mounting as a performance optimisation,
// this will likely not be the case.
func (d *Driver) Diff(id, parent string) (io.ReadCloser, error) {
title := fmt.Sprintf("lcowdriver: diff: %s", id)
// Get VHDX info
ld, err := getLayerDetails(d.dir(id))
if err != nil {
logrus.Debugf("%s: failed to get vhdx information of %s: %s", title, d.dir(id), err)
return nil, err
}
// Start the SVM with a mapped virtual disk. Note that if the SVM is
// already running and we are in global mode, this will be
// hot-added.
mvd := hcsshim.MappedVirtualDisk{
HostPath: ld.filename,
ContainerPath: hostToGuest(ld.filename),
CreateInUtilityVM: true,
ReadOnly: true,
}
logrus.Debugf("%s: starting service VM", title)
svm, err := d.startServiceVMIfNotRunning(id, []hcsshim.MappedVirtualDisk{mvd}, fmt.Sprintf("diff %s", id))
if err != nil {
return nil, err
}
logrus.Debugf("lcowdriver: diff: waiting for svm to finish booting")
err = svm.getStartError()
if err != nil {
d.terminateServiceVM(id, fmt.Sprintf("diff %s", id), false)
return nil, fmt.Errorf("lcowdriver: diff: svm failed to boot: %s", err)
}
// Obtain the tar stream for it
logrus.Debugf("%s: %s %s, size %d, ReadOnly %t", title, ld.filename, mvd.ContainerPath, ld.size, ld.isSandbox)
tarReadCloser, err := svm.config.VhdToTar(mvd.HostPath, mvd.ContainerPath, ld.isSandbox, ld.size)
if err != nil {
svm.hotRemoveVHDs(mvd)
d.terminateServiceVM(id, fmt.Sprintf("diff %s", id), false)
return nil, fmt.Errorf("%s failed to export layer to tar stream for id: %s, parent: %s : %s", title, id, parent, err)
}
logrus.Debugf("%s id %s parent %s completed successfully", title, id, parent)
// In safe/non-global mode, we can't tear down the service VM until things have been read.
return ioutils.NewReadCloserWrapper(tarReadCloser, func() error {
tarReadCloser.Close()
svm.hotRemoveVHDs(mvd)
d.terminateServiceVM(id, fmt.Sprintf("diff %s", id), false)
return nil
}), nil
}
// ApplyDiff extracts the changeset from the given diff into the
// layer with the specified id and parent, returning the size of the
// new layer in bytes. The layer should not be mounted when calling
// this function. Another way of describing this is that ApplyDiff writes
// to a new layer (a VHD in LCOW) the contents of a tarstream it's given.
func (d *Driver) ApplyDiff(id, parent string, diff io.Reader) (int64, error) {
logrus.Debugf("lcowdriver: applydiff: id %s", id)
svm, err := d.startServiceVMIfNotRunning(id, nil, fmt.Sprintf("applydiff %s", id))
if err != nil {
return 0, err
}
defer d.terminateServiceVM(id, fmt.Sprintf("applydiff %s", id), false)
logrus.Debugf("lcowdriver: applydiff: waiting for svm to finish booting")
err = svm.getStartError()
if err != nil {
return 0, fmt.Errorf("lcowdriver: applydiff: svm failed to boot: %s", err)
}
// TODO @jhowardmsft - the retries are temporary to overcome platform reliablity issues.
// Obviously this will be removed as platform bugs are fixed.
retries := 0
for {
retries++
size, err := svm.config.TarToVhd(filepath.Join(d.dataRoot, id, layerFilename), diff)
if err != nil {
if retries <= 10 {
continue
}
return 0, err
}
return size, err
}
}
// Changes produces a list of changes between the specified layer
// and its parent layer. If parent is "", then all changes will be ADD changes.
// The layer should not be mounted when calling this function.
func (d *Driver) Changes(id, parent string) ([]archive.Change, error) {
logrus.Debugf("lcowdriver: changes: id %s parent %s", id, parent)
// TODO @gupta-ak. Needs implementation with assistance from service VM
return nil, nil
}
// DiffSize calculates the changes between the specified layer
// and its parent and returns the size in bytes of the changes
// relative to its base filesystem directory.
func (d *Driver) DiffSize(id, parent string) (size int64, err error) {
logrus.Debugf("lcowdriver: diffsize: id %s", id)
// TODO @gupta-ak. Needs implementation with assistance from service VM
return 0, nil
}
// GetMetadata returns custom driver information.
func (d *Driver) GetMetadata(id string) (map[string]string, error) {
logrus.Debugf("lcowdriver: getmetadata: id %s", id)
m := make(map[string]string)
m["dir"] = d.dir(id)
return m, nil
}
// GetLayerPath gets the layer path on host (path to VHD/VHDX)
func (d *Driver) GetLayerPath(id string) (string, error) {
return d.dir(id), nil
}
// dir returns the absolute path to the layer.
func (d *Driver) dir(id string) string {
return filepath.Join(d.dataRoot, filepath.Base(id))
}
// getLayerChain returns the layer chain information.
func (d *Driver) getLayerChain(id string) ([]string, error) {
jPath := filepath.Join(d.dir(id), "layerchain.json")
logrus.Debugf("lcowdriver: getlayerchain: id %s json %s", id, jPath)
content, err := ioutil.ReadFile(jPath)
if os.IsNotExist(err) {
return nil, nil
} else if err != nil {
return nil, fmt.Errorf("lcowdriver: getlayerchain: %s unable to read layerchain file %s: %s", id, jPath, err)
}
var layerChain []string
err = json.Unmarshal(content, &layerChain)
if err != nil {
return nil, fmt.Errorf("lcowdriver: getlayerchain: %s failed to unmarshall layerchain file %s: %s", id, jPath, err)
}
return layerChain, nil
}
// setLayerChain stores the layer chain information on disk.
func (d *Driver) setLayerChain(id string, chain []string) error {
content, err := json.Marshal(&chain)
if err != nil {
return fmt.Errorf("lcowdriver: setlayerchain: %s failed to marshall layerchain json: %s", id, err)
}
jPath := filepath.Join(d.dir(id), "layerchain.json")
logrus.Debugf("lcowdriver: setlayerchain: id %s json %s", id, jPath)
err = ioutil.WriteFile(jPath, content, 0600)
if err != nil {
return fmt.Errorf("lcowdriver: setlayerchain: %s failed to write layerchain file: %s", id, err)
}
return nil
}
// getLayerDetails is a utility for getting a file name, size and indication of
// sandbox for a VHD(x) in a folder. A read-only layer will be layer.vhd. A
// read-write layer will be sandbox.vhdx.
func getLayerDetails(folder string) (*layerDetails, error) {
var fileInfo os.FileInfo
ld := &layerDetails{
isSandbox: false,
filename: filepath.Join(folder, layerFilename),
}
fileInfo, err := os.Stat(ld.filename)
if err != nil {
ld.filename = filepath.Join(folder, sandboxFilename)
if fileInfo, err = os.Stat(ld.filename); err != nil {
return nil, fmt.Errorf("failed to locate layer or sandbox in %s", folder)
}
ld.isSandbox = true
}
ld.size = fileInfo.Size()
return ld, nil
}
func (d *Driver) getAllMounts(id string) ([]hcsshim.MappedVirtualDisk, error) {
layerChain, err := d.getLayerChain(id)
if err != nil {
return nil, err
}
layerChain = append([]string{d.dir(id)}, layerChain...)
logrus.Debugf("getting all layers: %v", layerChain)
disks := make([]hcsshim.MappedVirtualDisk, len(layerChain), len(layerChain))
for i := range layerChain {
ld, err := getLayerDetails(layerChain[i])
if err != nil {
logrus.Debugf("Failed to get LayerVhdDetails from %s: %s", layerChain[i], err)
return nil, err
}
disks[i].HostPath = ld.filename
disks[i].ContainerPath = hostToGuest(ld.filename)
disks[i].CreateInUtilityVM = true
disks[i].ReadOnly = !ld.isSandbox
}
return disks, nil
}
func hostToGuest(hostpath string) string {
return fmt.Sprintf("/tmp/%s", filepath.Base(filepath.Dir(hostpath)))
}
func unionMountName(disks []hcsshim.MappedVirtualDisk) string {
return fmt.Sprintf("%s-mount", disks[0].ContainerPath)
}