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197 changes: 197 additions & 0 deletions computestorage/helpers.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,197 @@
package computestorage

import (
"context"
"os"
"path/filepath"
"syscall"

"github.com/Microsoft/go-winio/pkg/security"
"github.com/Microsoft/go-winio/vhd"
"github.com/pkg/errors"
"golang.org/x/sys/windows"
)

const defaultVHDXBlockSizeInMB = 1

// SetupContainerBaseLayer is a helper to setup a containers scratch. It
// will create and format the vhdx's inside and the size is configurable with the sizeInGB
// parameter.
//
// `layerPath` is the path to the base container layer on disk.
//
// `baseVhdPath` is the path to where the base vhdx for the base layer should be created.
//
// `diffVhdPath` is the path where the differencing disk for the base layer should be created.
//
// `sizeInGB` is the size in gigabytes to make the base vhdx.
func SetupContainerBaseLayer(ctx context.Context, layerPath, baseVhdPath, diffVhdPath string, sizeInGB uint64) (err error) {
var (
hivesPath = filepath.Join(layerPath, "Hives")
layoutPath = filepath.Join(layerPath, "Layout")
)

// We need to remove the hives directory and layout file as `SetupBaseOSLayer` fails if these files
// already exist. `SetupBaseOSLayer` will create these files internally. We also remove the base and
// differencing disks if they exist in case we're asking for a different size.
if _, err := os.Stat(hivesPath); err == nil {
if err := os.RemoveAll(hivesPath); err != nil {
return errors.Wrap(err, "failed to remove prexisting hives directory")
}
}
if _, err := os.Stat(layoutPath); err == nil {
if err := os.RemoveAll(layoutPath); err != nil {
return errors.Wrap(err, "failed to remove prexisting layout file")
}
}

if _, err := os.Stat(baseVhdPath); err == nil {
if err := os.RemoveAll(baseVhdPath); err != nil {
return errors.Wrap(err, "failed to remove base vhdx path")
}
}
if _, err := os.Stat(diffVhdPath); err == nil {
if err := os.RemoveAll(diffVhdPath); err != nil {
return errors.Wrap(err, "failed to remove differencing vhdx")
}
}

createParams := &vhd.CreateVirtualDiskParameters{
Version: 2,
Version2: vhd.CreateVersion2{
MaximumSize: sizeInGB * 1024 * 1024 * 1024,
BlockSizeInBytes: defaultVHDXBlockSizeInMB * 1024 * 1024,
},
}
handle, err := vhd.CreateVirtualDisk(baseVhdPath, vhd.VirtualDiskAccessNone, vhd.CreateVirtualDiskFlagNone, createParams)
if err != nil {
return errors.Wrap(err, "failed to create vhdx")
}

defer func() {
if err != nil {
syscall.CloseHandle(handle)
os.RemoveAll(baseVhdPath)
if os.Stat(diffVhdPath); err == nil {
os.RemoveAll(diffVhdPath)
}
}
}()

if err = FormatWritableLayerVhd(ctx, windows.Handle(handle)); err != nil {
return err
}
// Base vhd handle must be closed before calling SetupBaseLayer in case of Container layer
if err = syscall.CloseHandle(handle); err != nil {
return errors.Wrap(err, "failed to close vhdx handle")
}

options := OsLayerOptions{
Type: OsLayerTypeContainer,
}

// SetupBaseOSLayer expects an empty vhd handle for a container layer and will
// error out otherwise.
if err = SetupBaseOSLayer(ctx, layerPath, 0, options); err != nil {
return err
}
// Create the differencing disk that will be what's copied for the final rw layer
// for a container.
if err = vhd.CreateDiffVhd(diffVhdPath, baseVhdPath, defaultVHDXBlockSizeInMB); err != nil {
return errors.Wrap(err, "failed to create differencing disk")
}

if err = security.GrantVmGroupAccess(baseVhdPath); err != nil {
return errors.Wrapf(err, "failed to grant vm group access to %s", baseVhdPath)
}
if err = security.GrantVmGroupAccess(diffVhdPath); err != nil {
return errors.Wrapf(err, "failed to grant vm group access to %s", diffVhdPath)
}
return nil
}

// SetupUtilityVMBaseLayer is a helper to setup a UVMs scratch space. It will create and format
// the vhdx inside and the size is configurable by the sizeInGB parameter.
//
// `uvmPath` is the path to the UtilityVM filesystem.
//
// `baseVhdPath` is the path to where the base vhdx for the UVM should be created.
//
// `diffVhdPath` is the path where the differencing disk for the UVM should be created.
//
// `sizeInGB` specifies the size in gigabytes to make the base vhdx.
func SetupUtilityVMBaseLayer(ctx context.Context, uvmPath, baseVhdPath, diffVhdPath string, sizeInGB uint64) (err error) {
// Remove the base and differencing disks if they exist in case we're asking for a different size.
if _, err := os.Stat(baseVhdPath); err == nil {
if err := os.RemoveAll(baseVhdPath); err != nil {
return errors.Wrap(err, "failed to remove base vhdx")
}
}
if _, err := os.Stat(diffVhdPath); err == nil {
if err := os.RemoveAll(diffVhdPath); err != nil {
return errors.Wrap(err, "failed to remove differencing vhdx")
}
}

// Just create the vhdx for utilityVM layer, no need to format it.
createParams := &vhd.CreateVirtualDiskParameters{
Version: 2,
Version2: vhd.CreateVersion2{
MaximumSize: sizeInGB * 1024 * 1024 * 1024,
BlockSizeInBytes: defaultVHDXBlockSizeInMB * 1024 * 1024,
},
}
handle, err := vhd.CreateVirtualDisk(baseVhdPath, vhd.VirtualDiskAccessNone, vhd.CreateVirtualDiskFlagNone, createParams)
if err != nil {
return errors.Wrap(err, "failed to create vhdx")
}

defer func() {
if err != nil {
syscall.CloseHandle(handle)
os.RemoveAll(baseVhdPath)
if os.Stat(diffVhdPath); err == nil {
os.RemoveAll(diffVhdPath)
}
}
}()

// If it is a UtilityVM layer then the base vhdx must be attached when calling
// `SetupBaseOSLayer`
attachParams := &vhd.AttachVirtualDiskParameters{
Version: 2,
}
if err := vhd.AttachVirtualDisk(handle, vhd.AttachVirtualDiskFlagNone, attachParams); err != nil {
return errors.Wrapf(err, "failed to attach virtual disk")
}

options := OsLayerOptions{
Type: OsLayerTypeVM,
}
if err := SetupBaseOSLayer(ctx, uvmPath, windows.Handle(handle), options); err != nil {
return err
}

// Detach and close the handle after setting up the layer as we don't need the handle
// for anything else and we no longer need to be attached either.
if err = vhd.DetachVirtualDisk(handle); err != nil {
return errors.Wrap(err, "failed to detach vhdx")
}
if err = syscall.CloseHandle(handle); err != nil {
return errors.Wrap(err, "failed to close vhdx handle")
}

// Create the differencing disk that will be what's copied for the final rw layer
// for a container.
if err = vhd.CreateDiffVhd(diffVhdPath, baseVhdPath, defaultVHDXBlockSizeInMB); err != nil {
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@anmaxvl anmaxvl Dec 7, 2020

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the shared logic should be applied to both container and pod? if yes, is there a clean way to incapsulate it into one place, so we don't need to worry about having to remember to check both places? nothing needs to change, more of a patterns question here.

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Ditto here, not fully following the question :(

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mostly referring to similarities in what SetupContainerBaseLayer and SetupSandboxBaseLayer do in the beginning of the method (i.e. os.RemoveAll calls) on the same paths as well as in the end CreateDiffVhd/Grant*calls in the end, which is some shared code at the start and at the end with some different functionality in between.

so my question basically comes down to: can we dedup this somehow?

again, I'm not too worried about this. just seen some code that does stuff like:

func DoSomethingGenericWithSideEffect(func sideEffectAction(...), ...) {
    stuffAtTheStart()

    sideEffectAction(...)

    stuffAtTheEnd()
}

this is obviously not a place to do it, but for mostly educational purposes I was asking about other options (patterns) do we usually have?

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I wouldn't worry about this too much and we can discuss this offline

return errors.Wrap(err, "failed to create differencing disk")
}

if err := security.GrantVmGroupAccess(baseVhdPath); err != nil {
return errors.Wrapf(err, "failed to grant vm group access to %s", baseVhdPath)
}
if err := security.GrantVmGroupAccess(diffVhdPath); err != nil {
return errors.Wrapf(err, "failed to grant vm group access to %s", diffVhdPath)
}
return nil
}
2 changes: 1 addition & 1 deletion test/go.mod
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ module github.com/Microsoft/hcsshim/test
go 1.13

require (
github.com/Microsoft/go-winio v0.4.15-0.20200908182639-5b44b70ab3ab
github.com/Microsoft/go-winio v0.4.16-0.20201130162521-d1ffc52c7331
github.com/Microsoft/hcsshim v0.8.7
github.com/blang/semver v3.1.0+incompatible // indirect
github.com/containerd/containerd v1.3.2
Expand Down
2 changes: 2 additions & 0 deletions test/go.sum
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03
github.com/Microsoft/go-winio v0.4.15-0.20190919025122-fc70bd9a86b5 h1:ygIc8M6trr62pF5DucadTWGdEB4mEyvzi0e2nbcmcyA=
github.com/Microsoft/go-winio v0.4.15-0.20190919025122-fc70bd9a86b5/go.mod h1:tTuCMEN+UleMWgg9dVx4Hu52b1bJo+59jBh3ajtinzw=
github.com/Microsoft/go-winio v0.4.15-0.20200908182639-5b44b70ab3ab/go.mod h1:tTuCMEN+UleMWgg9dVx4Hu52b1bJo+59jBh3ajtinzw=
github.com/Microsoft/go-winio v0.4.16-0.20201130162521-d1ffc52c7331/go.mod h1:XB6nPKklQyQ7GC9LdcBEcBl8PF76WugXOPRXwdLnMv0=
github.com/Shopify/logrus-bugsnag v0.0.0-20171204204709-577dee27f20d/go.mod h1:HI8ITrYtUY+O+ZhtlqUnD8+KwNPOyugEhfP9fdUIaEQ=
github.com/aws/aws-sdk-go v1.15.11/go.mod h1:mFuSZ37Z9YOHbQEwBWztmVzqXrEkub65tZoCYDt7FT0=
github.com/beorn7/perks v0.0.0-20160804104726-4c0e84591b9a/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
Expand Down Expand Up @@ -194,6 +195,7 @@ golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7w
golang.org/x/sys v0.0.0-20191022100944-742c48ecaeb7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20200120151820-655fe14d7479 h1:LhLiKguPgZL+Tglay4GhVtfF0kb8cvOJ0dHTCBO8YNI=
golang.org/x/sys v0.0.0-20200120151820-655fe14d7479/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20201201145000-ef89a241ccb3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
Expand Down