Adds versioning for out-of-process storage driver

The registry currently only accepts storage driver versions with the
same major version and an equal or lower minor version as its own
current storage driver api version, but this may be changed in the
future if we decide to implement specific version cross-compatibility.
This commit is contained in:
Brian Bland 2014-11-06 12:16:14 -08:00
parent f02cfee950
commit 1ae5485998
5 changed files with 106 additions and 17 deletions

View file

@ -40,6 +40,8 @@ Storage drivers should call `factory.Register` with their driver name in an `ini
### Out-of-process drivers
As many users will run the registry as a pre-constructed docker container, storage drivers should also be distributable as IPC server executables. Drivers written in go should model the main method provided in `main/storagedriver/filesystem/filesystem.go`. Parameters to IPC drivers will be provided as a JSON-serialized map in the first argument to the process. These parameters should be validated and then a blocking call to `ipc.StorageDriverServer` should be made with a new storage driver.
Out-of-process drivers must also implement the `ipc.IPCStorageDriver` interface, which exposes a `Version` check for the storage driver. This is used to validate storage driver api compatibility at driver load-time.
## Testing
Storage driver test suites are provided in `storagedriver/testsuites/testsuites.go` and may be used for any storage driver written in go. Two methods are provided for registering test suites, `RegisterInProcessSuite` and `RegisterIPCSuite`, which run the same set of tests for the driver imported or managed over IPC respectively.

View file

@ -11,6 +11,7 @@ import (
"path"
"syscall"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/libchan"
"github.com/docker/libchan/spdy"
)
@ -22,6 +23,7 @@ type StorageDriverClient struct {
socket *os.File
transport *spdy.Transport
sender libchan.Sender
version storagedriver.Version
}
// NewDriverClient constructs a new out-of-process storage driver using the driver name and
@ -65,42 +67,62 @@ func (driver *StorageDriverClient) Start() error {
}
childSocket := os.NewFile(uintptr(fileDescriptors[0]), "childSocket")
parentSocket := os.NewFile(uintptr(fileDescriptors[1]), "parentSocket")
driver.socket = os.NewFile(uintptr(fileDescriptors[1]), "parentSocket")
driver.subprocess.Stdout = os.Stdout
driver.subprocess.Stderr = os.Stderr
driver.subprocess.ExtraFiles = []*os.File{childSocket}
if err = driver.subprocess.Start(); err != nil {
parentSocket.Close()
driver.Stop()
return err
}
if err = childSocket.Close(); err != nil {
parentSocket.Close()
driver.Stop()
return err
}
connection, err := net.FileConn(parentSocket)
connection, err := net.FileConn(driver.socket)
if err != nil {
parentSocket.Close()
driver.Stop()
return err
}
transport, err := spdy.NewClientTransport(connection)
driver.transport, err = spdy.NewClientTransport(connection)
if err != nil {
parentSocket.Close()
driver.Stop()
return err
}
sender, err := transport.NewSendChannel()
driver.sender, err = driver.transport.NewSendChannel()
if err != nil {
transport.Close()
parentSocket.Close()
driver.Stop()
return err
}
driver.socket = parentSocket
driver.transport = transport
driver.sender = sender
// Check the driver's version to determine compatibility
receiver, remoteSender := libchan.Pipe()
err = driver.sender.Send(&Request{Type: "Version", ResponseChannel: remoteSender})
if err != nil {
driver.Stop()
return err
}
var response VersionResponse
err = receiver.Receive(&response)
if err != nil {
driver.Stop()
return err
}
if response.Error != nil {
return response.Error
}
driver.version = response.Version
if driver.version.Major() != storagedriver.CurrentVersion.Major() || driver.version.Minor() > storagedriver.CurrentVersion.Minor() {
return IncompatibleVersionError{driver.version}
}
return nil
}
@ -108,10 +130,20 @@ func (driver *StorageDriverClient) Start() error {
// Stop stops the child process storage driver
// storagedriver.StorageDriver methods called after Stop will fail
func (driver *StorageDriverClient) Stop() error {
closeSenderErr := driver.sender.Close()
closeTransportErr := driver.transport.Close()
closeSocketErr := driver.socket.Close()
killErr := driver.subprocess.Process.Kill()
var closeSenderErr, closeTransportErr, closeSocketErr, killErr error
if driver.sender != nil {
closeSenderErr = driver.sender.Close()
}
if driver.transport != nil {
closeTransportErr = driver.transport.Close()
}
if driver.socket != nil {
closeSocketErr = driver.socket.Close()
}
if driver.subprocess != nil {
killErr = driver.subprocess.Process.Kill()
}
if closeSenderErr != nil {
return closeSenderErr

View file

@ -5,9 +5,29 @@ import (
"io"
"reflect"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/libchan"
)
// IPCStorageDriver is the interface which IPC storage drivers must implement. As external storage
// drivers may be defined to use a different version of the storagedriver.StorageDriver interface,
// we use an additional version check to determine compatiblity.
type IPCStorageDriver interface {
// Version returns the storagedriver.StorageDriver interface version which this storage driver
// implements, which is used to determine driver compatibility
Version() (storagedriver.Version, error)
}
// IncompatibleVersionError is returned when a storage driver is using an incompatible version of
// the storagedriver.StorageDriver api
type IncompatibleVersionError struct {
version storagedriver.Version
}
func (e IncompatibleVersionError) Error() string {
return fmt.Sprintf("Incompatible storage driver version: %s", e.version)
}
// Request defines a remote method call request
// A return value struct is to be sent over the ResponseChannel
type Request struct {
@ -38,6 +58,12 @@ func (err *responseError) Error() string {
// IPC method call response object definitions
// VersionResponse is a response for a Version request
type VersionResponse struct {
Version storagedriver.Version
Error *responseError
}
// ReadStreamResponse is a response for a ReadStream request
type ReadStreamResponse struct {
Reader io.ReadCloser

View file

@ -61,6 +61,11 @@ func receive(driver storagedriver.StorageDriver, receiver libchan.Receiver) {
// Responds to requests using the Request.ResponseChannel
func handleRequest(driver storagedriver.StorageDriver, request Request) {
switch request.Type {
case "Version":
err := request.ResponseChannel.Send(&VersionResponse{Version: storagedriver.CurrentVersion})
if err != nil {
panic(err)
}
case "GetContent":
path, _ := request.Parameters["Path"].(string)
content, err := driver.GetContent(path)

View file

@ -3,8 +3,32 @@ package storagedriver
import (
"fmt"
"io"
"strconv"
"strings"
)
// Version is a string representing the storage driver version, of the form Major.Minor.
// The registry must accept storage drivers with equal major version and greater minor version,
// but may not be compatible with older storage driver versions.
type Version string
// Major returns the major (primary) component of a version
func (version Version) Major() uint {
majorPart := strings.Split(string(version), ".")[0]
major, _ := strconv.ParseUint(majorPart, 10, 0)
return uint(major)
}
// Minor returns the minor (secondary) component of a version
func (version Version) Minor() uint {
minorPart := strings.Split(string(version), ".")[1]
minor, _ := strconv.ParseUint(minorPart, 10, 0)
return uint(minor)
}
// CurrentVersion is the current storage driver Version
const CurrentVersion Version = "0.1"
// StorageDriver defines methods that a Storage Driver must implement for a filesystem-like
// key/value object storage
type StorageDriver interface {