Persist the Ring

ipam/allocator.go

@@ -83,6 +83,7 @@ func NewAllocator(ourName mesh.PeerName, ourUID mesh.PeerUID, ourNickname string
 
 // Start runs the allocator goroutine
 func (alloc *Allocator) Start() {
+	alloc.loadPersistedRing()
 	actionChan := make(chan func(), mesh.ChannelSize)
 	alloc.actionChan = actionChan
 	alloc.ticker = time.NewTicker(tickInterval)
@@ -583,6 +584,7 @@ func (alloc *Allocator) ringUpdated() {
 		alloc.paxos = nil
 	}
 
+	alloc.persistRing()
 	alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
 	alloc.tryPendingOps()
 }
@@ -730,6 +732,7 @@ func (alloc *Allocator) donateSpace(r address.Range, to mesh.PeerName) {
 	}
 	alloc.debugln("Giving range", chunk, "to", to)
 	alloc.ring.GrantRangeToHost(chunk.Start, chunk.End, to)
+	alloc.persistRing()
 }
 
 func (alloc *Allocator) assertInvariants() {
@@ -762,6 +765,26 @@ func (alloc *Allocator) reportFreeSpace() {
 	alloc.ring.ReportFree(freespace)
 }
 
+// Persisting the Ring
+const (
+	ringIdent = "ring"
+)
+
+func (alloc *Allocator) persistRing() {
+	if err := alloc.db.Save(ringIdent, alloc.ring); err != nil {
+		common.Log.Errorf("Error persisting ring data: %s", err)
+	}
+}
+
+func (alloc *Allocator) loadPersistedRing() {
+	if err := alloc.db.Load(ringIdent, &alloc.ring); err != nil {
+		common.Log.Errorf("Error loading persisted ring data: %s", err)
+	}
+	if alloc.ring != nil {
+		alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
+	}
+}
+
 // Owned addresses
 
 func (alloc *Allocator) allOwned(ident string) []address.Address {

test/162_persist_ipam_2_test.sh

@@ -0,0 +1,43 @@
+#! /bin/bash
+
+. ./config.sh
+
+start_suite "Checking persistence of IPAM"
+
+launch_router_with_db() {
+    host=$1
+    shift
+    WEAVE_DOCKER_ARGS="-v /tmp:/db" weave_on $host launch-router --db-prefix=/db/test162- "$@"
+}
+
+# Remove any persisted data from previous runs
+run_on $HOST1 "sudo rm -f /tmp/test162-*"
+run_on $HOST2 "sudo rm -f /tmp/test162-*"
+
+launch_router_with_db $HOST1
+launch_router_with_db $HOST2 $HOST1
+
+start_container $HOST1 --name=c1
+C1=$(container_ip $HOST1 c1)
+start_container $HOST2 --name=c2
+assert_raises "exec_on $HOST2 c2 $PING $C1"
+
+stop_router_on $HOST1
+stop_router_on $HOST2
+
+# Start just HOST2; if nothing persisted it would form its own ring
+launch_router_with_db $HOST2
+start_container $HOST2 --name=c3
+C3=$(container_ip $HOST2 c3)
+assert_raises "[ $C3 != $C1 ]"
+
+stop_router_on $HOST2
+
+# Now start HOST1 with HOST2 down and see if it hangs when we launch a container
+launch_router_with_db $HOST1 $HOST2
+start_container $HOST1 --name=c4
+C4=$(container_ip $HOST1 c4)
+assert_raises "[ $C4 != $C1 ]"
+assert_raises "[ $C4 != $C3 ]"
+
+end_suite