expose driver capabilities to csi_hook

client/allocrunner/alloc_runner_hooks.go

@@ -168,7 +168,7 @@ func (ar *allocRunner) initRunnerHooks(config *clientconfig.Config) error {
 			logger:         hookLogger,
 		}),
 		newConsulSockHook(hookLogger, alloc, ar.allocDir, config.ConsulConfig),
-		newCSIHook(hookLogger, alloc, ar.rpcClient, ar.csiManager, hrs),
+		newCSIHook(ar, hookLogger, alloc, ar.rpcClient, ar.csiManager, hrs),
 	}
 
 	return nil

client/allocrunner/csi_hook.go

@@ -7,13 +7,15 @@ import (
 	hclog "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/nomad/client/pluginmanager/csimanager"
 	"github.com/hashicorp/nomad/nomad/structs"
+	"github.com/hashicorp/nomad/plugins/drivers"
 )
 
 // csiHook will wait for remote csi volumes to be attached to the host before
 // continuing.
 //
 // It is a noop for allocs that do not depend on CSI Volumes.
 type csiHook struct {
+	ar         *allocRunner
 	alloc      *structs.Allocation
 	logger     hclog.Logger
 	csimanager csimanager.Manager
@@ -88,7 +90,21 @@ func (c *csiHook) claimVolumesFromAlloc() (map[string]*volumeAndRequest, error)
 
 	// Initially, populate the result map with all of the requests
 	for alias, volumeRequest := range tg.Volumes {
+
 		if volumeRequest.Type == structs.VolumeTypeCSI {
+
+			for _, task := range tg.Tasks {
+				caps, err := c.ar.GetTaskDriverCapabilities(task.Name)
+				if err != nil {
+					return nil, fmt.Errorf("could not validate task driver capabilities: %v", err)
+				}
+				switch caps.Volumes {
+				case drivers.VolumeSupportNone, drivers.VolumeSupportHostOnly:
+					return nil, fmt.Errorf("task driver does not support CSI")
+				default:
+				}
+			}
+
 			result[alias] = &volumeAndRequest{request: volumeRequest}
 		}
 	}
@@ -125,8 +141,9 @@ func (c *csiHook) claimVolumesFromAlloc() (map[string]*volumeAndRequest, error)
 	return result, nil
 }
 
-func newCSIHook(logger hclog.Logger, alloc *structs.Allocation, rpcClient RPCer, csi csimanager.Manager, updater hookResourceSetter) *csiHook {
+func newCSIHook(ar *allocRunner, logger hclog.Logger, alloc *structs.Allocation, rpcClient RPCer, csi csimanager.Manager, updater hookResourceSetter) *csiHook {
 	return &csiHook{
+		ar:         ar,
 		alloc:      alloc,
 		logger:     logger.Named("csi_hook"),
 		rpcClient:  rpcClient,

plugins/drivers/client.go

@@ -71,6 +71,8 @@ func (d *driverPluginClient) Capabilities() (*Capabilities, error) {
 		default:
 			caps.FSIsolation = FSIsolationNone
 		}
+
+		caps.Volumes = VolumeSupport(resp.Capabilities.Volumes)
 	}
 
 	return caps, nil

plugins/drivers/driver.go

@@ -163,6 +163,9 @@ type Capabilities struct {
 	// MustInitiateNetwork tells Nomad that the driver must create the network
 	// namespace and that the CreateNetwork and DestroyNetwork RPCs are implemented.
 	MustInitiateNetwork bool
+
+	// Volumes tells Nomad which volume mounting options the driver supports.
+	Volumes VolumeSupport
 }
 
 func (c *Capabilities) HasNetIsolationMode(m NetIsolationMode) bool {
@@ -197,6 +200,15 @@ type NetworkIsolationSpec struct {
 	Labels map[string]string
 }
 
+type VolumeSupport int32
+
+const (
+	VolumeSupportAll VolumeSupport = iota
+	VolumeSupportNone
+	VolumeSupportHostOnly
+	VolumeSupportCSIOnly
+)
+
 type TerminalSize struct {
 	Height int
 	Width  int