nomad: testing fsm snapshot and restore

nomad/fsm.go

@@ -7,10 +7,18 @@ import (
 	"time"
 
 	"github.com/armon/go-metrics"
+	"github.com/hashicorp/go-msgpack/codec"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/raft"
 )
 
+var (
+	msgpackHandle = &codec.MsgpackHandle{
+		RawToString: true,
+		WriteExt:    true,
+	}
+)
+
 // nomadFSM implements a finite state machine that is used
 // along with Raft to provide strong consistency. We implement
 // this outside the Server to avoid exposing this outside the package.
@@ -24,7 +32,11 @@ type nomadFSM struct {
 // state in a way that can be accessed concurrently with operations
 // that may modify the live state.
 type nomadSnapshot struct {
-	state *StateSnapshot
+	snap *StateSnapshot
+}
+
+// snapshotHeader is the first entry in our snapshot
+type snapshotHeader struct {
 }
 
 // NewFSMPath is used to construct a new FSM with a blank state
@@ -139,14 +151,112 @@ func (n *nomadFSM) Snapshot() (raft.FSMSnapshot, error) {
 
 func (n *nomadFSM) Restore(old io.ReadCloser) error {
 	defer old.Close()
+
+	// Create a new state store
+	state, err := NewStateStore(n.logOutput)
+	if err != nil {
+		return err
+	}
+	n.state = state
+
+	// Start the state restore
+	restore, err := state.Restore()
+	if err != nil {
+		return err
+	}
+	defer restore.Abort()
+
+	// Create a decoder
+	dec := codec.NewDecoder(old, msgpackHandle)
+
+	// Read in the header
+	var header snapshotHeader
+	if err := dec.Decode(&header); err != nil {
+		return err
+	}
+
+	// Populate the new state
+	msgType := make([]byte, 1)
+	for {
+		// Read the message type
+		_, err := old.Read(msgType)
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return err
+		}
+
+		// Decode
+		switch structs.MessageType(msgType[0]) {
+		case structs.RegisterRequestType:
+			var req structs.RegisterRequest
+			if err := dec.Decode(&req); err != nil {
+				return err
+			}
+			if err := restore.NodeRestore(req.Node); err != nil {
+				return err
+			}
+
+		default:
+			return fmt.Errorf("Unrecognized msg type: %v", msgType)
+		}
+	}
+
+	// Commit the state restore
+	restore.Commit()
 	return nil
 }
 
 func (s *nomadSnapshot) Persist(sink raft.SnapshotSink) error {
 	defer metrics.MeasureSince([]string{"nomad", "fsm", "persist"}, time.Now())
+	// Register the nodes
+	encoder := codec.NewEncoder(sink, msgpackHandle)
+
+	// Write the header
+	header := snapshotHeader{}
+	if err := encoder.Encode(&header); err != nil {
+		sink.Cancel()
+		return err
+	}
+
+	// Write all the data out
+	if err := s.persistNodes(sink, encoder); err != nil {
+		sink.Cancel()
+		return err
+	}
 	return nil
 }
 
-func (s *nomadSnapshot) Release() {
-	return
+func (s *nomadSnapshot) persistNodes(sink raft.SnapshotSink,
+	encoder *codec.Encoder) error {
+	// Get all the nodes
+	nodes, err := s.snap.Nodes()
+	if err != nil {
+		return err
+	}
+
+	var req structs.RegisterRequest
+	for {
+		// Get the next item
+		raw := nodes.Next()
+		if raw == nil {
+			break
+		}
+
+		// Prepare the request struct
+		node := raw.(*structs.Node)
+		req = structs.RegisterRequest{Node: node}
+
+		// Write out a node registration
+		sink.Write([]byte{byte(structs.RegisterRequestType)})
+		if err := encoder.Encode(&req); err != nil {
+			return err
+		}
+	}
+	return nil
 }
+
+// Release is a no-op, as we just need to GC the pointer
+// to the state store snapshot. There is nothing to explicitly
+// cleanup.
+func (s *nomadSnapshot) Release() {}

nomad/fsm_test.go

@@ -1,13 +1,33 @@
 package nomad
 
 import (
+	"bytes"
 	"os"
+	"reflect"
 	"testing"
 
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/raft"
 )
 
+type MockSink struct {
+	*bytes.Buffer
+	cancel bool
+}
+
+func (m *MockSink) ID() string {
+	return "Mock"
+}
+
+func (m *MockSink) Cancel() error {
+	m.cancel = true
+	return nil
+}
+
+func (m *MockSink) Close() error {
+	return nil
+}
+
 func testFSM(t *testing.T) *nomadFSM {
 	fsm, err := NewFSM(os.Stderr)
 	if err != nil {
@@ -137,3 +157,50 @@ func TestFSM_UpdateNodeStatus(t *testing.T) {
 		t.Fatalf("bad node: %#v", node)
 	}
 }
+
+func testSnapshotRestore(t *testing.T, fsm *nomadFSM) *nomadFSM {
+	// Snapshot
+	snap, err := fsm.Snapshot()
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	defer snap.Release()
+
+	// Persist
+	buf := bytes.NewBuffer(nil)
+	sink := &MockSink{buf, false}
+	if err := snap.Persist(sink); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Try to restore on a new FSM
+	fsm2 := testFSM(t)
+
+	// Do a restore
+	if err := fsm2.Restore(sink); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	return fsm2
+}
+
+func TestFSM_SnapshotRestore_Nodes(t *testing.T) {
+	// Add some state
+	fsm := testFSM(t)
+	state := fsm.State()
+	node1 := mockNode()
+	state.RegisterNode(1000, node1)
+	node2 := mockNode()
+	state.RegisterNode(1001, node2)
+
+	// Verify the contents
+	fsm2 := testSnapshotRestore(t, fsm)
+	state2 := fsm2.State()
+	out1, _ := state2.GetNodeByID(node1.ID)
+	out2, _ := state2.GetNodeByID(node2.ID)
+	if !reflect.DeepEqual(node1, out1) {
+		t.Fatalf("bad: \n%#v\n%#v", out1, node1)
+	}
+	if !reflect.DeepEqual(node2, out2) {
+		t.Fatalf("bad: \n%#v\n%#v", out2, node2)
+	}
+}

nomad/state_store_test.go

@@ -25,13 +25,13 @@ func mockNode() *structs.Node {
 		ID:         generateUUID(),
 		Datacenter: "dc1",
 		Name:       "foobar",
-		Attributes: map[string]interface{}{
+		Attributes: map[string]string{
 			"os":            "linux",
 			"arch":          "x86",
 			"version":       "0.1.0",
-			"driver.docker": 1,
+			"driver.docker": "1.0.0",
 		},
-		Resouces: &structs.Resources{
+		Resources: &structs.Resources{
 			CPU:      4.0,
 			MemoryMB: 8192,
 			DiskMB:   100 * 1024,
@@ -50,7 +50,7 @@ func mockNode() *structs.Node {
 			MemoryMB: 256,
 			DiskMB:   4 * 1024,
 		},
-		Links: map[string]interface{}{
+		Links: map[string]string{
 			"consul": "foobar.dc1",
 		},
 		Meta: map[string]string{

nomad/structs/structs.go

@@ -160,11 +160,11 @@ type Node struct {
 	// data that can be used for constraints. Examples
 	// include "os=linux", "arch=386", "driver.docker=1",
 	// "docker.runtime=1.8.3"
-	Attributes map[string]interface{}
+	Attributes map[string]string
 
 	// Resources is the available resources on the client.
 	// For example 'cpu=2' 'memory=2048'
-	Resouces *Resources
+	Resources *Resources
 
 	// Reserved is the set of resources that are reserved,
 	// and should be subtracted from the total resources for
@@ -181,7 +181,7 @@ type Node struct {
 	// Links are used to 'link' this client to external
 	// systems. For example 'consul=foo.dc1' 'aws=i-83212'
 	// 'ami=ami-123'
-	Links map[string]interface{}
+	Links map[string]string
 
 	// Meta is used to associate arbitrary metadata with this
 	// client. This is opaque to Nomad.