api: add StartedAt in Node.DrainStrategy

api/nodes.go

@@ -521,6 +521,9 @@ type DrainStrategy struct {
 	// ForceDeadline is the deadline time for the drain after which drains will
 	// be forced
 	ForceDeadline time.Time
+
+	// StartedAt is the time the drain process started
+	StartedAt time.Time
 }
 
 // DrainSpec describes a Node's drain behavior.

nomad/node_endpoint.go

@@ -523,8 +523,10 @@ func (n *Node) UpdateDrain(args *structs.NodeUpdateDrainRequest,
 		return fmt.Errorf("node not found")
 	}
 
+	now := time.Now().UTC()
+
 	// Update the timestamp of when the node status was updated
-	args.UpdatedAt = time.Now().Unix()
+	args.UpdatedAt = now.Unix()
 
 	// COMPAT: Remove in 0.9. Attempt to upgrade the request if it is of the old
 	// format.
@@ -536,9 +538,19 @@ func (n *Node) UpdateDrain(args *structs.NodeUpdateDrainRequest,
 		}
 	}
 
-	// Mark the deadline time
-	if args.DrainStrategy != nil && args.DrainStrategy.Deadline.Nanoseconds() > 0 {
-		args.DrainStrategy.ForceDeadline = time.Now().Add(args.DrainStrategy.Deadline)
+	// Setup drain strategy
+	if args.DrainStrategy != nil {
+		// Mark start time for the drain
+		if node.DrainStrategy == nil {
+			args.DrainStrategy.StartedAt = now
+		} else {
+			args.DrainStrategy.StartedAt = node.DrainStrategy.StartedAt
+		}
+
+		// Mark the deadline time
+		if args.DrainStrategy.Deadline.Nanoseconds() > 0 {
+			args.DrainStrategy.ForceDeadline = now.Add(args.DrainStrategy.Deadline)
+		}
 	}
 
 	// Construct the node event

nomad/node_endpoint_test.go

@@ -906,6 +906,17 @@ func TestClientEndpoint_UpdateDrain(t *testing.T) {
 	// now+deadline should be after the forced deadline
 	require.True(time.Now().Add(strategy.Deadline).After(out.DrainStrategy.ForceDeadline))
 
+	drainStartedAt := out.DrainStrategy.StartedAt
+	// StartedAt should be close to the time the drain started
+	require.WithinDuration(beforeUpdate, drainStartedAt, 1*time.Second)
+
+	// StartedAt shouldn't change if a new request comes while still draining
+	require.Nil(msgpackrpc.CallWithCodec(codec, "Node.UpdateDrain", dereg, &resp2))
+	ws = memdb.NewWatchSet()
+	out, err = state.NodeByID(ws, node.ID)
+	require.NoError(err)
+	require.True(out.DrainStrategy.StartedAt.Equal(drainStartedAt))
+
 	// Register a system job
 	job := mock.SystemJob()
 	require.Nil(s1.State().UpsertJob(10, job))
@@ -923,16 +934,16 @@ func TestClientEndpoint_UpdateDrain(t *testing.T) {
 	ws = memdb.NewWatchSet()
 	out, err = state.NodeByID(ws, node.ID)
 	require.NoError(err)
-	require.Len(out.Events, 3)
-	require.Equal(NodeDrainEventDrainDisabled, out.Events[2].Message)
+	require.Len(out.Events, 4)
+	require.Equal(NodeDrainEventDrainDisabled, out.Events[3].Message)
 
 	// Check that calling UpdateDrain with the same DrainStrategy does not emit
 	// a node event.
 	require.Nil(msgpackrpc.CallWithCodec(codec, "Node.UpdateDrain", dereg, &resp3))
 	ws = memdb.NewWatchSet()
 	out, err = state.NodeByID(ws, node.ID)
 	require.NoError(err)
-	require.Len(out.Events, 3)
+	require.Len(out.Events, 4)
 }
 
 func TestClientEndpoint_UpdateDrain_ACL(t *testing.T) {

nomad/structs/structs.go

@@ -1445,6 +1445,9 @@ type DrainStrategy struct {
 	// ForceDeadline is the deadline time for the drain after which drains will
 	// be forced
 	ForceDeadline time.Time
+
+	// StartedAt is the time the drain process started
+	StartedAt time.Time
 }
 
 func (d *DrainStrategy) Copy() *DrainStrategy {