Add basic infrastructure to use BoltDB for persistence

.gitmodules

@@ -55,3 +55,6 @@
 [submodule "vendor/github.com/vishvananda/netns"]
 	path = vendor/github.com/vishvananda/netns
 	url = https://github.com/vishvananda/netns.git
+[submodule "vendor/github.com/boltdb/bolt"]
+	path = vendor/github.com/boltdb/bolt
+	url = https://github.com/boltdb/bolt

Makefile

@@ -63,7 +63,7 @@ testrunner: $(RUNNER_EXE) $(TEST_TLS_EXE)
 
 $(EXES): $(BUILD_UPTODATE)
 $(WEAVER_EXE) $(WEAVEPROXY_EXE) $(WEAVEUTIL_EXE): common/*.go common/*/*.go net/*.go net/*/*.go
-$(WEAVER_EXE): router/*.go ipam/*.go ipam/*/*.go nameserver/*.go prog/weaver/*.go
+$(WEAVER_EXE): router/*.go ipam/*.go ipam/*/*.go db/*.go nameserver/*.go prog/weaver/*.go
 $(WEAVEPROXY_EXE): proxy/*.go prog/weaveproxy/*.go
 $(WEAVEUTIL_EXE): prog/weaveutil/*.go
 $(SIGPROXY_EXE): prog/sigproxy/*.go

db/boltdb.go

@@ -0,0 +1,81 @@
+package db
+
+import (
+	"bytes"
+	"encoding/gob"
+	"fmt"
+
+	"github.com/boltdb/bolt"
+)
+
+type DB interface {
+	Load(string, interface{}) error
+	Save(string, interface{}) error
+}
+
+type BoltDB struct {
+	db *bolt.DB
+}
+
+var (
+	versionIdent       = []byte("version")
+	persistenceVersion = []byte{1, 0} // major.minor
+	topBucket          = []byte("top")
+)
+
+func NewBoltDB(dbPathname string) (*BoltDB, error) {
+	db, err := bolt.Open(dbPathname, 0660, nil)
+	if err != nil {
+		return nil, fmt.Errorf("[boltDB] Unable to open %s: %s", dbPathname, err)
+	}
+	// check the persistence version
+	err = db.Update(func(tx *bolt.Tx) error {
+		if top := tx.Bucket(topBucket); top == nil {
+			top, err := tx.CreateBucket(topBucket)
+			if err != nil {
+				return err
+			}
+			if err := top.Put(versionIdent, persistenceVersion); err != nil {
+				return err
+			}
+		} else {
+			if checkVersion := top.Get(versionIdent); checkVersion != nil {
+				if checkVersion[0] != persistenceVersion[0] {
+					return fmt.Errorf("[boltDB] Cannot use persistence file %s - version %x", dbPathname, checkVersion)
+				}
+			}
+		}
+		return nil
+	})
+	return &BoltDB{db: db}, err
+}
+
+func (d *BoltDB) Load(ident string, data interface{}) error {
+	return d.db.View(func(tx *bolt.Tx) error {
+		b := tx.Bucket(topBucket)
+		v := b.Get([]byte(ident))
+		if v == nil {
+			return nil
+		}
+		reader := bytes.NewReader(v)
+		decoder := gob.NewDecoder(reader)
+		err := decoder.Decode(data)
+		return err
+	})
+}
+
+func (d *BoltDB) Save(ident string, data interface{}) error {
+	return d.db.Update(func(tx *bolt.Tx) error {
+		b := tx.Bucket(topBucket)
+		buf := new(bytes.Buffer)
+		enc := gob.NewEncoder(buf)
+		if err := enc.Encode(data); err != nil {
+			return err
+		}
+		return b.Put([]byte(ident), buf.Bytes())
+	})
+}
+
+func (d *BoltDB) Close() error {
+	return d.db.Close()
+}

prog/weaver/main.go

@@ -17,6 +17,7 @@ import (
 
 	. "github.com/weaveworks/weave/common"
 	"github.com/weaveworks/weave/common/docker"
+	"github.com/weaveworks/weave/db"
 	"github.com/weaveworks/weave/ipam"
 	"github.com/weaveworks/weave/nameserver"
 	weavenet "github.com/weaveworks/weave/net"
@@ -67,6 +68,7 @@ func main() {
 		dnsConfig          dnsConfig
 		datapathName       string
 		trustedSubnetStr   string
+		dbPrefix           string
 
 		defaultDockerHost = "unix:///var/run/docker.sock"
 	)
@@ -101,6 +103,7 @@ func main() {
 	mflag.DurationVar(&dnsConfig.ClientTimeout, []string{"-dns-fallback-timeout"}, nameserver.DefaultClientTimeout, "timeout for fallback DNS requests")
 	mflag.StringVar(&dnsConfig.EffectiveListenAddress, []string{"-dns-effective-listen-address"}, "", "address DNS will actually be listening, after Docker port mapping")
 	mflag.StringVar(&datapathName, []string{"-datapath"}, "", "ODP datapath name")
+	mflag.StringVar(&dbPrefix, []string{"-db-prefix"}, "weave", "pathname/prefix of filename to store data")
 
 	mflag.StringVar(&trustedSubnetStr, []string{"-trusted-subnets"}, "", "Command separated list of trusted subnets in CIDR notation")
 
@@ -159,6 +162,10 @@ func main() {
 	config.TrustedSubnets = parseTrustedSubnets(trustedSubnetStr)
 	config.PeerDiscovery = !noDiscovery
 
+	db, err := db.NewBoltDB(dbPrefix + "data.db")
+	checkFatal(err)
+	defer db.Close()
+
 	router := weave.NewNetworkRouter(config, networkConfig, name, nickName, overlay)
 	Log.Println("Our name is", router.Ourself)