dynamic host volumes: volume fingerprinting

api/nodes.go

@@ -517,6 +517,8 @@ type DriverInfo struct {
 type HostVolumeInfo struct {
 	Path     string
 	ReadOnly bool
+	// ID is set for dynamic host volumes only.
+	ID string
 }
 
 // HostNetworkInfo is used to return metadata about a given HostNetwork

client/client.go

@@ -411,6 +411,7 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulProxie
 		c.updateNodeFromDriver,
 		c.updateNodeFromDevices,
 		c.updateNodeFromCSI,
+		c.updateNodeFromHostVol,
 	)
 
 	// Initialize the server manager
@@ -535,16 +536,14 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulProxie
 	c.devicemanager = devManager
 	c.pluginManagers.RegisterAndRun(devManager)
 
-	c.hostVolumeManager, err = hvm.NewHostVolumeManager(logger,
-		c.stateDB, hostVolumeRequestTimeout,
-		cfg.HostVolumePluginDir,
-		cfg.AllocMountsDir)
-	if err != nil {
-		// NewHostVolumeManager will only err if it fails to read state store,
-		// or if one or more required plugins do not exist, so halt the client
-		// because something needs to be fixed by a cluster admin.
-		return nil, err
-	}
+	// set up dynamic host volume manager
+	c.hostVolumeManager = hvm.NewHostVolumeManager(logger, hvm.Config{
+		PluginDir:      cfg.HostVolumePluginDir,
+		SharedMountDir: cfg.AllocMountsDir,
+		StateMgr:       c.stateDB,
+		UpdateNodeVols: c.batchNodeUpdates.updateNodeFromHostVolume,
+	})
+	c.pluginManagers.RegisterAndRun(c.hostVolumeManager)
 
 	// Set up the service registration wrapper using the Consul and Nomad
 	// implementations. The Nomad implementation is only ever used on the

client/host_volume_endpoint.go

@@ -50,7 +50,7 @@ func (v *HostVolume) Delete(
 	ctx, cancelFn := v.requestContext()
 	defer cancelFn()
 
-	_, err := v.c.hostVolumeManager.Delete(ctx, req) // db TODO(1.10.0): cresp is empty... why return it?
+	_, err := v.c.hostVolumeManager.Delete(ctx, req)
 	if err != nil {
 		v.c.logger.Error("failed to delete host volume", "ID", req.ID, "error", err)
 		return err

client/host_volume_endpoint_test.go

@@ -6,13 +6,13 @@ package client
 import (
 	"path/filepath"
 	"testing"
-	"time"
 
 	"github.com/hashicorp/nomad/ci"
 	hvm "github.com/hashicorp/nomad/client/hostvolumemanager"
 	"github.com/hashicorp/nomad/client/state"
 	cstructs "github.com/hashicorp/nomad/client/structs"
 	"github.com/hashicorp/nomad/helper/testlog"
+	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/shoenig/test/must"
 )
 
@@ -26,16 +26,22 @@ func TestHostVolume(t *testing.T) {
 	client.stateDB = memdb
 
 	tmp := t.TempDir()
-	var err error
+	manager := hvm.NewHostVolumeManager(testlog.HCLogger(t), hvm.Config{
+		StateMgr:       client.stateDB,
+		UpdateNodeVols: client.updateNodeFromHostVol,
+		PluginDir:      "/no/ext/plugins",
+		SharedMountDir: tmp,
+	})
+	client.hostVolumeManager = manager
 	expectDir := filepath.Join(tmp, "test-vol-id")
-	client.hostVolumeManager, err = hvm.NewHostVolumeManager(testlog.HCLogger(t),
-		client.stateDB, time.Second, "/no/ext/plugins", tmp)
-	must.NoError(t, err)
 
 	t.Run("happy", func(t *testing.T) {
+
+		/* create */
+
 		req := &cstructs.ClientHostVolumeCreateRequest{
-			ID:       "test-vol-id",
 			Name:     "test-vol-name",
+			ID:       "test-vol-id",
 			PluginID: "mkdir", // real plugin really makes a dir
 		}
 		var resp cstructs.ClientHostVolumeCreateResponse
@@ -56,8 +62,19 @@ func TestHostVolume(t *testing.T) {
 			CreateReq: req,
 		}
 		must.Eq(t, expectState, vols[0])
+		// and should be fingerprinted
+		must.Eq(t, hvm.VolumeMap{
+			req.Name: {
+				ID:   req.ID,
+				Name: req.Name,
+				Path: expectDir,
+			},
+		}, client.Node().HostVolumes)
+
+		/* delete */
 
 		delReq := &cstructs.ClientHostVolumeDeleteRequest{
+			Name:     "test-vol-name",
 			ID:       "test-vol-id",
 			PluginID: "mkdir",
 			HostPath: expectDir,
@@ -72,6 +89,8 @@ func TestHostVolume(t *testing.T) {
 		vols, err = memdb.GetDynamicHostVolumes()
 		must.NoError(t, err)
 		must.Len(t, 0, vols)
+		// and the fingerprint, too
+		must.Eq(t, map[string]*structs.ClientHostVolumeConfig{}, client.Node().HostVolumes)
 	})
 
 	t.Run("missing plugin", func(t *testing.T) {
@@ -92,9 +111,12 @@ func TestHostVolume(t *testing.T) {
 
 	t.Run("error from plugin", func(t *testing.T) {
 		// "mkdir" plugin can't create a directory within a file
-		client.hostVolumeManager, err = hvm.NewHostVolumeManager(testlog.HCLogger(t),
-			client.stateDB, time.Second, "/no/ext/plugins", "host_volume_endpoint_test.go")
-		must.NoError(t, err)
+		client.hostVolumeManager = hvm.NewHostVolumeManager(testlog.HCLogger(t), hvm.Config{
+			StateMgr:       client.stateDB,
+			UpdateNodeVols: client.updateNodeFromHostVol,
+			PluginDir:      "/no/ext/plugins",
+			SharedMountDir: "host_volume_endpoint_test.go",
+		})
 
 		req := &cstructs.ClientHostVolumeCreateRequest{
 			ID:       "test-vol-id",

client/hostvolumemanager/host_volume_plugin.go

@@ -59,17 +59,28 @@ func (p *HostVolumePluginMkdir) Create(_ context.Context,
 		"path", path)
 	log.Debug("running plugin")
 
+	resp := &HostVolumePluginCreateResponse{
+		Path:      path,
+		SizeBytes: 0,
+	}
+
+	if _, err := os.Stat(path); err == nil {
+		// already exists
+		return resp, nil
+	} else if !os.IsNotExist(err) {
+		// doesn't exist, but some other path error
+		log.Debug("error with plugin", "error", err)
+		return nil, err
+	}
+
 	err := os.Mkdir(path, 0o700)
 	if err != nil {
 		log.Debug("error with plugin", "error", err)
 		return nil, err
 	}
 
 	log.Debug("plugin ran successfully")
-	return &HostVolumePluginCreateResponse{
-		Path:      path,
-		SizeBytes: 0,
-	}, nil
+	return resp, nil
 }
 
 func (p *HostVolumePluginMkdir) Delete(_ context.Context, req *cstructs.ClientHostVolumeDeleteRequest) error {

client/hostvolumemanager/host_volumes.go

@@ -7,12 +7,13 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
-	"time"
+	"sync"
 
 	"github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/go-multierror"
 	cstructs "github.com/hashicorp/nomad/client/structs"
 	"github.com/hashicorp/nomad/helper"
+	"github.com/hashicorp/nomad/nomad/structs"
 )
 
 var (
@@ -26,42 +27,68 @@ type HostVolumeStateManager interface {
 	DeleteDynamicHostVolume(string) error
 }
 
+type Config struct {
+	// PluginDir is where external plugins may be found.
+	PluginDir string
+
+	// SharedMountDir is where plugins should place the directory
+	// that will later become a volume HostPath
+	SharedMountDir string
+
+	// StateMgr manages client state to restore on agent restarts.
+	StateMgr HostVolumeStateManager
+
+	// UpdateNodeVols is run to update the node when a volume is created
+	// or deleted.
+	UpdateNodeVols HostVolumeNodeUpdater
+}
+
 type HostVolumeManager struct {
 	pluginDir      string
 	sharedMountDir string
 	stateMgr       HostVolumeStateManager
-
-	log hclog.Logger
+	updateNodeVols HostVolumeNodeUpdater
+	log            hclog.Logger
 }
 
-func NewHostVolumeManager(logger hclog.Logger,
-	state HostVolumeStateManager, restoreTimeout time.Duration,
-	pluginDir, sharedMountDir string) (*HostVolumeManager, error) {
-
-	log := logger.Named("host_volume_mgr")
-
-	// db TODO(1.10.0): how do we define the external mounter plugins? plugin configs?
-	hvm := &HostVolumeManager{
-		pluginDir:      pluginDir,
-		sharedMountDir: sharedMountDir,
-		stateMgr:       state,
-		log:            log,
+func NewHostVolumeManager(logger hclog.Logger, config Config) *HostVolumeManager {
+	// db TODO(1.10.0): document plugin config options
+	return &HostVolumeManager{
+		pluginDir:      config.PluginDir,
+		sharedMountDir: config.SharedMountDir,
+		stateMgr:       config.StateMgr,
+		updateNodeVols: config.UpdateNodeVols,
+		log:            logger.Named("host_volume_manager"),
 	}
+}
 
-	if err := hvm.restoreState(state, restoreTimeout); err != nil {
-		return nil, err
+func genVolConfig(req *cstructs.ClientHostVolumeCreateRequest, resp *HostVolumePluginCreateResponse) *structs.ClientHostVolumeConfig {
+	if req == nil || resp == nil {
+		return nil
+	}
+	return &structs.ClientHostVolumeConfig{
+		Name: req.Name,
+		ID:   req.ID,
+		Path: resp.Path,
+
+		// dynamic volumes, like CSI, have more robust `capabilities`,
+		// so we always set ReadOnly to false, and let the scheduler
+		// decide when to ignore this and check capabilities instead.
+		ReadOnly: false,
 	}
-
-	return hvm, nil
 }
 
-func (hvm *HostVolumeManager) restoreState(state HostVolumeStateManager, timeout time.Duration) error {
-	vols, err := state.GetDynamicHostVolumes()
+func (hvm *HostVolumeManager) restoreFromState(ctx context.Context) (VolumeMap, error) {
+	vols, err := hvm.stateMgr.GetDynamicHostVolumes()
 	if err != nil {
-		return err
+		return nil, err
 	}
+
+	volumes := make(VolumeMap)
+	var mut sync.Mutex
+
 	if len(vols) == 0 {
-		return nil // nothing to do
+		return volumes, nil // nothing to do
 	}
 
 	// re-"create" the volumes - plugins have the best knowledge of their
@@ -76,17 +103,20 @@ func (hvm *HostVolumeManager) restoreState(state HostVolumeStateManager, timeout
 				return err
 			}
 
-			ctx, cancel := context.WithTimeout(context.Background(), timeout)
-			defer cancel()
-			if _, err := plug.Create(ctx, vol.CreateReq); err != nil {
+			resp, err := plug.Create(ctx, vol.CreateReq)
+			if err != nil {
 				// plugin execution errors are only logged
 				hvm.log.Error("failed to restore", "plugin_id", vol.CreateReq.PluginID, "volume_id", vol.ID, "error", err)
+				return nil
 			}
+			mut.Lock()
+			volumes[vol.CreateReq.Name] = genVolConfig(vol.CreateReq, resp)
+			mut.Unlock()
 			return nil
 		})
 	}
 	mErr := group.Wait()
-	return helper.FlattenMultierror(mErr.ErrorOrNil())
+	return volumes, helper.FlattenMultierror(mErr.ErrorOrNil())
 }
 
 func (hvm *HostVolumeManager) getPlugin(id string) (HostVolumePlugin, error) {
@@ -139,9 +169,11 @@ func (hvm *HostVolumeManager) Create(ctx context.Context,
 		return nil, helper.FlattenMultierror(err)
 	}
 
-	// db TODO(1.10.0): now we need to add the volume to the node fingerprint!
+	hvm.updateNodeVols(req.Name, genVolConfig(req, pluginResp))
 
 	resp := &cstructs.ClientHostVolumeCreateResponse{
+		VolumeName:    req.Name,
+		VolumeID:      req.ID,
 		HostPath:      pluginResp.Path,
 		CapacityBytes: pluginResp.SizeBytes,
 	}
@@ -162,12 +194,17 @@ func (hvm *HostVolumeManager) Delete(ctx context.Context,
 		return nil, err
 	}
 
-	resp := &cstructs.ClientHostVolumeDeleteResponse{}
-
 	if err := hvm.stateMgr.DeleteDynamicHostVolume(req.ID); err != nil {
 		hvm.log.Error("failed to delete volume in state", "volume_id", req.ID, "error", err)
 		return nil, err // bail so a user may retry
 	}
 
+	hvm.updateNodeVols(req.Name, nil)
+
+	resp := &cstructs.ClientHostVolumeDeleteResponse{
+		VolumeName: req.Name,
+		VolumeID:   req.ID,
+	}
+
 	return resp, nil
 }