nomad: support DevMode configuration

nomad/config.go

@@ -23,6 +23,10 @@ type Config struct {
 	// DataDir is the directory to store our state in
 	DataDir string
 
+	// DevMode is used for development purposes only and limits the
+	// use of persistence or state.
+	DevMode bool
+
 	// LogOutput is the location to write logs to. If this is not set,
 	// logs will go to stderr.
 	LogOutput io.Writer

nomad/fsm.go

@@ -17,7 +17,6 @@ import (
 type nomadFSM struct {
 	logOutput io.Writer
 	logger    *log.Logger
-	path      string
 	state     *StateStore
 }
 
@@ -29,7 +28,7 @@ type nomadSnapshot struct {
 }
 
 // NewFSMPath is used to construct a new FSM with a blank state
-func NewFSM(path string, logOutput io.Writer) (*nomadFSM, error) {
+func NewFSM(logOutput io.Writer) (*nomadFSM, error) {
 	// Create a state store
 	state, err := NewStateStore(logOutput)
 	if err != nil {
@@ -39,7 +38,6 @@ func NewFSM(path string, logOutput io.Writer) (*nomadFSM, error) {
 	fsm := &nomadFSM{
 		logOutput: logOutput,
 		logger:    log.New(logOutput, "", log.LstdFlags),
-		path:      path,
 		state:     state,
 	}
 	return fsm, nil

nomad/server.go

@@ -14,7 +14,6 @@ import (
 
 const (
 	raftState         = "raft/"
-	tmpStatePath      = "tmp/"
 	snapshotsRetained = 2
 
 	// raftLogCacheSize is the maximum number of logs to cache in-memory.
@@ -34,6 +33,7 @@ type Server struct {
 	raftLayer     *RaftLayer
 	raftPeers     raft.PeerStore
 	raftStore     *raftboltdb.BoltStore
+	raftInmem     *raft.InmemStore
 	raftTransport *raft.NetworkTransport
 
 	// fsm is the state machine used with Raft
@@ -111,69 +111,84 @@ func (s *Server) Shutdown() error {
 // setupRaft is used to setup and initialize Raft
 func (s *Server) setupRaft() error {
 	// If we are in bootstrap mode, enable a single node cluster
-	if s.config.Bootstrap {
+	if s.config.Bootstrap || s.config.DevMode {
 		s.config.RaftConfig.EnableSingleNode = true
 	}
 
-	// Create the base state path
-	statePath := filepath.Join(s.config.DataDir, tmpStatePath)
-	if err := os.RemoveAll(statePath); err != nil {
-		return err
-	}
-	if err := ensurePath(statePath, true); err != nil {
-		return err
-	}
-
 	// Create the FSM
 	var err error
-	s.fsm, err = NewFSM(statePath, s.config.LogOutput)
+	s.fsm, err = NewFSM(s.config.LogOutput)
 	if err != nil {
 		return err
 	}
 
-	// Create the base raft path
-	path := filepath.Join(s.config.DataDir, raftState)
-	if err := ensurePath(path, true); err != nil {
-		return err
-	}
-
-	// Create the backend raft store for logs and stable storage
-	store, err := raftboltdb.NewBoltStore(filepath.Join(path, "raft.db"))
-	if err != nil {
-		return err
-	}
-	s.raftStore = store
-
-	// Wrap the store in a LogCache to improve performance
-	cacheStore, err := raft.NewLogCache(raftLogCacheSize, store)
-	if err != nil {
-		store.Close()
-		return err
-	}
-
-	// Create the snapshot store
-	snapshots, err := raft.NewFileSnapshotStore(path, snapshotsRetained, s.config.LogOutput)
-	if err != nil {
-		store.Close()
-		return err
-	}
-
 	// Create a transport layer
-	trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second, s.config.LogOutput)
+	trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second,
+		s.config.LogOutput)
 	s.raftTransport = trans
 
-	// Setup the peer store
-	s.raftPeers = raft.NewJSONPeers(path, trans)
+	// Create the backend raft store for logs and stable storage
+	var log raft.LogStore
+	var stable raft.StableStore
+	var snap raft.SnapshotStore
+	var peers raft.PeerStore
+	if s.config.DevMode {
+		store := raft.NewInmemStore()
+		s.raftInmem = store
+		stable = store
+		log = store
+		snap = raft.NewDiscardSnapshotStore()
+		peers = &raft.StaticPeers{}
 
-	// Ensure local host is always included if we are in bootstrap mode
-	if s.config.Bootstrap {
-		peers, err := s.raftPeers.Peers()
+	} else {
+		// Create the base raft path
+		path := filepath.Join(s.config.DataDir, raftState)
+		if err := ensurePath(path, true); err != nil {
+			return err
+		}
+
+		// Create the BoltDB backend
+		store, err := raftboltdb.NewBoltStore(filepath.Join(path, "raft.db"))
+		if err != nil {
+			return err
+		}
+		s.raftStore = store
+		stable = store
+
+		// Wrap the store in a LogCache to improve performance
+		cacheStore, err := raft.NewLogCache(raftLogCacheSize, store)
 		if err != nil {
 			store.Close()
 			return err
 		}
-		if !raft.PeerContained(peers, trans.LocalAddr()) {
-			s.raftPeers.SetPeers(raft.AddUniquePeer(peers, trans.LocalAddr()))
+		log = cacheStore
+
+		// Create the snapshot store
+		snapshots, err := raft.NewFileSnapshotStore(path, snapshotsRetained, s.config.LogOutput)
+		if err != nil {
+			if s.raftStore != nil {
+				s.raftStore.Close()
+			}
+			return err
+		}
+		snap = snapshots
+
+		// Setup the peer store
+		s.raftPeers = raft.NewJSONPeers(path, trans)
+		peers = s.raftPeers
+	}
+
+	// Ensure local host is always included if we are in bootstrap mode
+	if s.config.RaftConfig.EnableSingleNode {
+		p, err := peers.Peers()
+		if err != nil {
+			if s.raftStore != nil {
+				s.raftStore.Close()
+			}
+			return err
+		}
+		if !raft.PeerContained(p, trans.LocalAddr()) {
+			peers.SetPeers(raft.AddUniquePeer(p, trans.LocalAddr()))
 		}
 	}
 
@@ -181,10 +196,12 @@ func (s *Server) setupRaft() error {
 	s.config.RaftConfig.LogOutput = s.config.LogOutput
 
 	// Setup the Raft store
-	s.raft, err = raft.NewRaft(s.config.RaftConfig, s.fsm, cacheStore, store,
-		snapshots, s.raftPeers, trans)
+	s.raft, err = raft.NewRaft(s.config.RaftConfig, s.fsm, log, stable,
+		snap, peers, trans)
 	if err != nil {
-		store.Close()
+		if s.raftStore != nil {
+			s.raftStore.Close()
+		}
 		trans.Close()
 		return err
 	}