Merge pull request #8604 from mheon/volume_plugin_impl

Initial implementation of volume plugins

1 files changed, 309 insertions, 0 deletions

diff --git a/test/testvol/main.go b/test/testvol/main.go
new file mode 100644
index 000000000..14f253aa7
--- /dev/null
+++ b/test/testvol/main.go
@@ -0,0 +1,309 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/docker/go-plugins-helpers/volume"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "testvol",
+	Short: "testvol - volume plugin for Podman",
+	Long:  `Creates simple directory volumes using the Volume Plugin API for testing volume plugin functionality`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		return startServer(config.sockName)
+	},
+	PersistentPreRunE: before,
+}
+
+// Configuration for the volume plugin
+type cliConfig struct {
+	logLevel string
+	sockName string
+	path     string
+}
+
+// Default configuration is stored here. Will be overwritten by flags.
+var config cliConfig = cliConfig{
+	logLevel: "error",
+	sockName: "test-volume-plugin",
+}
+
+func init() {
+	rootCmd.Flags().StringVar(&config.sockName, "sock-name", config.sockName, "Name of unix socket for plugin")
+	rootCmd.Flags().StringVar(&config.path, "path", "", "Path to initialize state and mount points")
+	rootCmd.PersistentFlags().StringVar(&config.logLevel, "log-level", config.logLevel, "Log messages including and over the specified level: debug, info, warn, error, fatal, panic")
+}
+
+func before(cmd *cobra.Command, args []string) error {
+	if config.logLevel == "" {
+		config.logLevel = "error"
+	}
+
+	level, err := logrus.ParseLevel(config.logLevel)
+	if err != nil {
+		return err
+	}
+
+	logrus.SetLevel(level)
+
+	return nil
+}
+
+func main() {
+	if err := rootCmd.Execute(); err != nil {
+		logrus.Errorf("Error running volume plugin: %v", err)
+		os.Exit(1)
+	}
+
+	os.Exit(0)
+}
+
+// startServer runs the HTTP server and responds to requests
+func startServer(socketPath string) error {
+	logrus.Debugf("Starting server...")
+
+	if config.path == "" {
+		path, err := ioutil.TempDir("", "test_volume_plugin")
+		if err != nil {
+			return errors.Wrapf(err, "error getting directory for plugin")
+		}
+		config.path = path
+	} else {
+		pathStat, err := os.Stat(config.path)
+		if err != nil {
+			return errors.Wrapf(err, "unable to access requested plugin state directory")
+		}
+		if !pathStat.IsDir() {
+			return errors.Errorf("cannot use %v as plugin state dir as it is not a directory", config.path)
+		}
+	}
+
+	handle, err := makeDirDriver(config.path)
+	if err != nil {
+		return errors.Wrapf(err, "error making volume driver")
+	}
+	logrus.Infof("Using %s for volume path", config.path)
+
+	server := volume.NewHandler(handle)
+	if err := server.ServeUnix(socketPath, 0); err != nil {
+		return errors.Wrapf(err, "error starting server")
+	}
+	return nil
+}
+
+// DirDriver is a trivial volume driver implementation.
+// the volumes field maps name to volume
+type DirDriver struct {
+	lock        sync.Mutex
+	volumesPath string
+	volumes     map[string]*dirVol
+}
+
+type dirVol struct {
+	name       string
+	path       string
+	options    map[string]string
+	mounts     map[string]bool
+	createTime time.Time
+}
+
+// Make a new DirDriver.
+func makeDirDriver(path string) (volume.Driver, error) {
+	drv := new(DirDriver)
+	drv.volumesPath = path
+	drv.volumes = make(map[string]*dirVol)
+
+	return drv, nil
+}
+
+// Capabilities returns the capabilities of the driver.
+func (d *DirDriver) Capabilities() *volume.CapabilitiesResponse {
+	logrus.Infof("Hit Capabilities() endpoint")
+
+	return &volume.CapabilitiesResponse{
+		volume.Capability{
+			"local",
+		},
+	}
+}
+
+// Create creates a volume.
+func (d *DirDriver) Create(opts *volume.CreateRequest) error {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Create() endpoint")
+
+	if _, exists := d.volumes[opts.Name]; exists {
+		return errors.Errorf("volume with name %s already exists", opts.Name)
+	}
+
+	newVol := new(dirVol)
+	newVol.name = opts.Name
+	newVol.mounts = make(map[string]bool)
+	newVol.options = make(map[string]string)
+	newVol.createTime = time.Now()
+	for k, v := range opts.Options {
+		newVol.options[k] = v
+	}
+
+	volPath := filepath.Join(d.volumesPath, opts.Name)
+	if err := os.Mkdir(volPath, 0755); err != nil {
+		return errors.Wrapf(err, "error making volume directory")
+	}
+	newVol.path = volPath
+
+	d.volumes[opts.Name] = newVol
+
+	logrus.Debugf("Made volume with name %s and path %s", newVol.name, newVol.path)
+
+	return nil
+}
+
+// List lists all volumes available.
+func (d *DirDriver) List() (*volume.ListResponse, error) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit List() endpoint")
+
+	vols := new(volume.ListResponse)
+	vols.Volumes = []*volume.Volume{}
+
+	for _, vol := range d.volumes {
+		newVol := new(volume.Volume)
+		newVol.Name = vol.name
+		newVol.Mountpoint = vol.path
+		newVol.CreatedAt = vol.createTime.String()
+		vols.Volumes = append(vols.Volumes, newVol)
+		logrus.Debugf("Adding volume %s to list response", newVol.Name)
+	}
+
+	return vols, nil
+}
+
+// Get retrieves a single volume.
+func (d *DirDriver) Get(req *volume.GetRequest) (*volume.GetResponse, error) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Get() endpoint")
+
+	vol, exists := d.volumes[req.Name]
+	if !exists {
+		logrus.Debugf("Did not find volume %s", req.Name)
+		return nil, errors.Errorf("no volume with name %s found", req.Name)
+	}
+
+	logrus.Debugf("Found volume %s", req.Name)
+
+	resp := new(volume.GetResponse)
+	resp.Volume = new(volume.Volume)
+	resp.Volume.Name = vol.name
+	resp.Volume.Mountpoint = vol.path
+	resp.Volume.CreatedAt = vol.createTime.String()
+
+	return resp, nil
+}
+
+// Remove removes a single volume.
+func (d *DirDriver) Remove(req *volume.RemoveRequest) error {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Remove() endpoint")
+
+	vol, exists := d.volumes[req.Name]
+	if !exists {
+		logrus.Debugf("Did not find volume %s", req.Name)
+		return errors.Errorf("no volume with name %s found")
+	}
+	logrus.Debugf("Found volume %s", req.Name)
+
+	if len(vol.mounts) > 0 {
+		logrus.Debugf("Cannot remove %s, is mounted", req.Name)
+		return errors.Errorf("volume %s is mounted and cannot be removed")
+	}
+
+	delete(d.volumes, req.Name)
+
+	if err := os.RemoveAll(vol.path); err != nil {
+		return errors.Wrapf(err, "error removing mountpoint of volume %s", req.Name)
+	}
+
+	logrus.Debugf("Removed volume %s", req.Name)
+
+	return nil
+}
+
+// Path returns the path a single volume is mounted at.
+func (d *DirDriver) Path(req *volume.PathRequest) (*volume.PathResponse, error) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Path() endpoint")
+
+	// TODO: Should we return error if not mounted?
+
+	vol, exists := d.volumes[req.Name]
+	if !exists {
+		logrus.Debugf("Cannot locate volume %s", req.Name)
+		return nil, errors.Errorf("no volume with name %s found", req.Name)
+	}
+
+	return &volume.PathResponse{
+		vol.path,
+	}, nil
+}
+
+// Mount mounts the volume.
+func (d *DirDriver) Mount(req *volume.MountRequest) (*volume.MountResponse, error) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Mount() endpoint")
+
+	vol, exists := d.volumes[req.Name]
+	if !exists {
+		logrus.Debugf("Cannot locate volume %s", req.Name)
+		return nil, errors.Errorf("no volume with name %s found", req.Name)
+	}
+
+	vol.mounts[req.ID] = true
+
+	return &volume.MountResponse{
+		vol.path,
+	}, nil
+}
+
+// Unmount unmounts the volume.
+func (d *DirDriver) Unmount(req *volume.UnmountRequest) error {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	logrus.Infof("Hit Unmount() endpoint")
+
+	vol, exists := d.volumes[req.Name]
+	if !exists {
+		logrus.Debugf("Cannot locate volume %s", req.Name)
+		return errors.Errorf("no volume with name %s found", req.Name)
+	}
+
+	mount := vol.mounts[req.ID]
+	if !mount {
+		logrus.Debugf("Volume %s is not mounted by %s", req.Name, req.ID)
+		return errors.Errorf("volume %s is not mounted by %s", req.Name, req.ID)
+	}
+
+	delete(vol.mounts, req.ID)
+
+	return nil
+}