Use a data volume container for BoltDB files.

We provide a very small image to use for this container.
Also we add an empty weavedata.db file to weave image so it doesn't crash when run without volume override

Makefile

@@ -30,15 +30,17 @@ BUILD_UPTODATE=.build.uptodate
 WEAVER_UPTODATE=.weaver.uptodate
 WEAVEEXEC_UPTODATE=.weaveexec.uptodate
 PLUGIN_UPTODATE=.plugin.uptodate
+WEAVEDB_UPTODATE=.weavedb.uptodate
 
-IMAGES_UPTODATE=$(WEAVER_UPTODATE) $(WEAVEEXEC_UPTODATE) $(PLUGIN_UPTODATE) $(BUILD_UPTODATE)
+IMAGES_UPTODATE=$(WEAVER_UPTODATE) $(WEAVEEXEC_UPTODATE) $(PLUGIN_UPTODATE) $(BUILD_UPTODATE) $(WEAVEDB_UPTODATE)
 
 WEAVER_IMAGE=$(DOCKERHUB_USER)/weave
 WEAVEEXEC_IMAGE=$(DOCKERHUB_USER)/weaveexec
 PLUGIN_IMAGE=$(DOCKERHUB_USER)/plugin
 BUILD_IMAGE=$(DOCKERHUB_USER)/weavebuild
+WEAVEDB_IMAGE=$(DOCKERHUB_USER)/weavedb
 
-IMAGES=$(WEAVER_IMAGE) $(WEAVEEXEC_IMAGE) $(PLUGIN_IMAGE)
+IMAGES=$(WEAVER_IMAGE) $(WEAVEEXEC_IMAGE) $(PLUGIN_IMAGE) $(WEAVEDB_IMAGE)
 
 WEAVE_EXPORT=weave.tar.gz
 
@@ -147,6 +149,10 @@ $(PLUGIN_UPTODATE): prog/plugin/Dockerfile $(PLUGIN_EXE) $(WEAVEEXEC_UPTODATE)
 	$(SUDO) docker build -t $(PLUGIN_IMAGE) prog/plugin
 	touch $@
 
+$(WEAVEDB_UPTODATE): prog/weavedb/Dockerfile
+	$(SUDO) docker build -t $(WEAVEDB_IMAGE) prog/weavedb
+	touch $@
+
 $(WEAVE_EXPORT): $(IMAGES_UPTODATE)
 	$(SUDO) DOCKER_HOST=$(DOCKER_HOST) docker save $(addsuffix :latest,$(IMAGES)) | gzip > $@
 

prog/weavedb/Dockerfile

@@ -0,0 +1,6 @@
+# This is a nearly-empty image that we use to create a data-only container for persistence
+FROM scratch
+MAINTAINER Weaveworks Inc <help@weave.works>
+ENTRYPOINT ["data-only"]
+# Work round Docker refusing to save an empty image
+COPY Dockerfile /

prog/weaver/Dockerfile

@@ -3,5 +3,6 @@ MAINTAINER Weaveworks Inc <help@weave.works>
 LABEL works.weave.role=system
 WORKDIR /home/weave
 ADD ./weaver /home/weave/
+ADD weavedata.db /weavedb/
 COPY ca-certificates.crt /etc/ssl/certs/
 ENTRYPOINT ["/home/weave/weaver"]

prog/weaver/main.go

@@ -166,7 +166,7 @@ func main() {
 	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(&trustedSubnetStr, []string{"-trusted-subnets"}, "", "comma-separated list of trusted subnets in CIDR notation")
-	mflag.StringVar(&dbPrefix, []string{"-db-prefix"}, "weave", "pathname/prefix of filename to store data")
+	mflag.StringVar(&dbPrefix, []string{"-db-prefix"}, "/weavedb/weave", "pathname/prefix of filename to store data")
 
 	// crude way of detecting that we probably have been started in a
 	// container, with `weave launch` --> suppress misleading paths in

weave

@@ -21,6 +21,7 @@ MIN_DOCKER_VERSION=1.6.0
 DOCKERHUB_USER=${DOCKERHUB_USER:-weaveworks}
 BASE_EXEC_IMAGE=$DOCKERHUB_USER/weaveexec
 EXEC_IMAGE=$BASE_EXEC_IMAGE:$IMAGE_VERSION
+WEAVEDB_IMAGE=$DOCKERHUB_USER/weavedb
 PROXY_HOST=${PROXY_HOST:-$(echo "${DOCKER_HOST#tcp://}" | cut -s -d: -f1)}
 PROXY_HOST=${PROXY_HOST:-127.0.0.1}
 DOCKER_CLIENT_HOST=${DOCKER_CLIENT_HOST:-$DOCKER_HOST}
@@ -384,7 +385,10 @@ IMAGE=$BASE_IMAGE:$IMAGE_VERSION
 BASE_PLUGIN_IMAGE=$DOCKERHUB_USER/plugin
 PLUGIN_IMAGE=$BASE_PLUGIN_IMAGE:$IMAGE_VERSION
 PLUGIN_CONTAINER_NAME=weaveplugin
+# Note VOLUMES_CONTAINER which is for weavewait should change when you upgrade Weave
 VOLUMES_CONTAINER_NAME=weavevolumes-$IMAGE_VERSION
+# DB files should remain when you upgrade, so version number not included in name
+DB_CONTAINER_NAME=weavedb
 
 DOCKER_BRIDGE=${DOCKER_BRIDGE:-docker0}
 CONTAINER_NAME=${WEAVE_CONTAINER_NAME:-weave}
@@ -1679,12 +1683,19 @@ launch_router() {
         fi
     fi
 
+    # Create a data-only container for persistence data
+    if ! docker inspect -f ' ' $DB_CONTAINER_NAME > /dev/null 2>&1 ; then
+       docker create -v /weavedb --name=$DB_CONTAINER_NAME \
+           --label=weavevolumes $WEAVEDB_IMAGE >/dev/null
+    fi
+
     # Set WEAVE_DOCKER_ARGS in the environment in order to supply
     # additional parameters, such as resource limits, to docker
     # when launching the weave container.
     start_if_necessary router $CONTAINER_NAME $IMAGE \
         $(docker_run_options) \
         --restart=always \
+        --volumes-from $DB_CONTAINER_NAME \
         -e WEAVE_PASSWORD \
         -e CHECKPOINT_DISABLE \
         $WEAVE_DOCKER_ARGS $IMAGE $COVERAGE_ARGS \