CSI: ensure initial unpublish state is checkpointed (#14675) (#14716)

A test flake revealed a bug in the CSI unpublish workflow, where an unpublish
that comes from a client that's successfully done the node-unpublish step will
not have the claim checkpointed if the controller-unpublish step fails. This
will result in a delay in releasing the volume claim until the next GC.

This changeset also ensures we're using a new snapshot after each write to raft,
and fixes two timing issues in test where either the volume watcher can
unpublish before the unpublish RPC is sent or we don't wait long enough in
resource-restricted environements like GHA.

Co-authored-by: Tim Gross <tgross@hashicorp.com>

.changelog/14675.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+csi: Fixed a bug where a volume that was successfully unmounted by the client but then failed controller unpublishing would not be marked free until garbage collection ran.
+```

nomad/core_sched_test.go

@@ -2459,7 +2459,7 @@ func TestCoreScheduler_CSIBadState_ClaimGC(t *testing.T) {
 			}
 		}
 		return true
-	}, time.Second*1, 10*time.Millisecond, "invalid claims should be marked for GC")
+	}, time.Second*5, 10*time.Millisecond, "invalid claims should be marked for GC")
 
 }
 

nomad/csi_endpoint.go

@@ -574,6 +574,16 @@ func (v *CSIVolume) Unpublish(args *structs.CSIVolumeUnpublishRequest, reply *st
 
 	claim := args.Claim
 
+	// we need to checkpoint when we first get the claim to ensure we've set the
+	// initial "past claim" state, otherwise a client that unpublishes (skipping
+	// the node unpublish b/c it's done that work) fail to get written if the
+	// controller unpublish fails.
+	vol = vol.Copy()
+	err = v.checkpointClaim(vol, claim)
+	if err != nil {
+		return err
+	}
+
 	// previous checkpoints may have set the past claim state already.
 	// in practice we should never see CSIVolumeClaimStateControllerDetached
 	// but having an option for the state makes it easy to add a checkpoint
@@ -619,6 +629,13 @@ RELEASE_CLAIM:
 // problems. This function should only be called on a copy of the volume.
 func (v *CSIVolume) nodeUnpublishVolume(vol *structs.CSIVolume, claim *structs.CSIVolumeClaim) error {
 	v.logger.Trace("node unpublish", "vol", vol.ID)
+
+	// We need a new snapshot after each checkpoint
+	snap, err := v.srv.fsm.State().Snapshot()
+	if err != nil {
+		return err
+	}
+
 	if claim.AllocationID != "" {
 		err := v.nodeUnpublishVolumeImpl(vol, claim)
 		if err != nil {
@@ -631,8 +648,7 @@ func (v *CSIVolume) nodeUnpublishVolume(vol *structs.CSIVolume, claim *structs.C
 	// The RPC sent from the 'nomad node detach' command or GC won't have an
 	// allocation ID set so we try to unpublish every terminal or invalid
 	// alloc on the node, all of which will be in PastClaims after denormalizing
-	state := v.srv.fsm.State()
-	vol, err := state.CSIVolumeDenormalize(memdb.NewWatchSet(), vol)
+	vol, err = snap.CSIVolumeDenormalize(memdb.NewWatchSet(), vol)
 	if err != nil {
 		return err
 	}
@@ -702,10 +718,15 @@ func (v *CSIVolume) controllerUnpublishVolume(vol *structs.CSIVolume, claim *str
 		return nil
 	}
 
-	state := v.srv.fsm.State()
+	// We need a new snapshot after each checkpoint
+	snap, err := v.srv.fsm.State().Snapshot()
+	if err != nil {
+		return err
+	}
+
 	ws := memdb.NewWatchSet()
 
-	plugin, err := state.CSIPluginByID(ws, vol.PluginID)
+	plugin, err := snap.CSIPluginByID(ws, vol.PluginID)
 	if err != nil {
 		return fmt.Errorf("could not query plugin: %v", err)
 	} else if plugin == nil {
@@ -717,7 +738,7 @@ func (v *CSIVolume) controllerUnpublishVolume(vol *structs.CSIVolume, claim *str
 		return nil
 	}
 
-	vol, err = state.CSIVolumeDenormalize(ws, vol)
+	vol, err = snap.CSIVolumeDenormalize(ws, vol)
 	if err != nil {
 		return err
 	}

nomad/csi_endpoint_test.go

@@ -568,8 +568,8 @@ func TestCSIVolumeEndpoint_Unpublish(t *testing.T) {
 
 			// setup: create an alloc that will claim our volume
 			alloc := mock.BatchAlloc()
-			alloc.NodeID = node.ID
-			alloc.ClientStatus = structs.AllocClientStatusFailed
+			alloc.NodeID = tc.nodeID
+			alloc.ClientStatus = structs.AllocClientStatusRunning
 
 			otherAlloc := mock.BatchAlloc()
 			otherAlloc.NodeID = tc.otherNodeID
@@ -579,7 +579,7 @@ func TestCSIVolumeEndpoint_Unpublish(t *testing.T) {
 			require.NoError(t, state.UpsertAllocs(structs.MsgTypeTestSetup, index,
 				[]*structs.Allocation{alloc, otherAlloc}))
 
-			// setup: claim the volume for our alloc
+			// setup: claim the volume for our to-be-failed alloc
 			claim := &structs.CSIVolumeClaim{
 				AllocationID:   alloc.ID,
 				NodeID:         node.ID,
@@ -617,10 +617,19 @@ func TestCSIVolumeEndpoint_Unpublish(t *testing.T) {
 				},
 			}
 
+			alloc = alloc.Copy()
+			alloc.ClientStatus = structs.AllocClientStatusFailed
+			index++
+			require.NoError(t, state.UpsertAllocs(structs.MsgTypeTestSetup, index,
+				[]*structs.Allocation{alloc}))
+
 			err = msgpackrpc.CallWithCodec(codec, "CSIVolume.Unpublish", req,
 				&structs.CSIVolumeUnpublishResponse{})
 
-			vol, volErr := state.CSIVolumeByID(nil, ns, volID)
+			snap, snapErr := state.Snapshot()
+			require.NoError(t, snapErr)
+
+			vol, volErr := snap.CSIVolumeByID(nil, ns, volID)
 			require.NoError(t, volErr)
 			require.NotNil(t, vol)