diff --git a/mongo/hooks/mongo_database-relation-joined b/mongo/hooks/mongo_database-relation-joined
index ce5cba5..41409a4 100755
--- a/mongo/hooks/mongo_database-relation-joined
+++ b/mongo/hooks/mongo_database-relation-joined
@@ -10,29 +10,35 @@ DBNAME=$(relation-get dbname) || {
 }
 
 
-dbs=$(mongo:db:ls) || exit 1
-if matching_db=$(e "$dbs" | egrep "[a-zA-Z0-9.-_]*_${DBNAME}"); then
-    if e "$dbs" | grep "^${DBNAME}$"; then
-        err "Error: unexpected database '$matching_db'" \
-            "found along with database named '${DBNAME}'."
-        exit 1
-    fi
-    ## Let's take for granted that only current source service is
-    ## concerned by the database. We need to restart source service
-    ## container only if already running.
-    container_ids=($(get_running_containers_for_service "$MASTER_BASE_SERVICE_NAME"))
-    for container_id in "${container_ids[@]}"; do
-        mongo_url=$(docker:container:env_get "$container_id" MONGO_URL) || return 1
-        if [[ "$mongo_url" == */"${matching_db}"* ]]; then
-            info "Attempting to stop current containers of service $MASTER_BASE_SERVICE_NAME"
-            docker stop -t 5 "$container_id"
+ensure_db_docker_running
+
+if dbs=$(mongo:db:ls); then
+    if matching_db=$(e "$dbs" | egrep "[a-zA-Z0-9.-_]*_${DBNAME}"); then
+        if e "$dbs" | grep "^${DBNAME}$"; then
+            err "Error: unexpected database '$matching_db'" \
+                "found along with database named '${DBNAME}'."
+            exit 1
         fi
-    done
-
-    mongo:db:rename "$matching_db" "${DBNAME}"
-
-    ## we DO NOT want to start the stopped container again as they are not
-    ## properly configured
+        ## Let's take for granted that only current source service is
+        ## concerned by the database. We need to restart source service
+        ## container only if already running.
+        container_ids=($(get_running_containers_for_service "$MASTER_BASE_SERVICE_NAME"))
+        for container_id in "${container_ids[@]}"; do
+            mongo_url=$(docker:container:env_get "$container_id" MONGO_URL) || return 1
+            if [[ "$mongo_url" == */"${matching_db}"* ]]; then
+                info "Attempting to stop current containers of service $MASTER_BASE_SERVICE_NAME"
+                docker stop -t 5 "$container_id"
+            fi
+        done
+
+        mongo:db:rename "$matching_db" "${DBNAME}"
+
+        ## we DO NOT want to start the stopped container again as they are not
+        ## properly configured
+    fi
+else
+    err "Failed to query for database list"
+    exit 14
 fi
 
 ## ReplicaSet initialization
diff --git a/mongo/lib/common b/mongo/lib/common
index 7ed3237..9824eee 100644
--- a/mongo/lib/common
+++ b/mongo/lib/common
@@ -20,23 +20,60 @@ _set_server_db_params() {
 
 _set_db_params() {
     local docker_ip="$1" docker_network="$2"
+    ## XXXvlab: include this in compose-core
+    if [ "${_db_params}" != "$docker_ip:$docker_network" ]; then
+        db_docker_opts+=("--network" "$docker_network")
 
-    db_docker_opts+=("--network" "$docker_network")
-
-    db_cmd_opts+=("--host" "$docker_ip")
-    check_command="db.serverStatus().ok"
+        db_cmd_opts+=("--host" "$docker_ip")
+        check_command="db.serverStatus().ok"
+        _db_params="$docker_ip:$docker_network"
+        echo callers: "${FUNCNAME[@]}" >&2
+    fi
 }
 
+
 ddb() { dcmd mongo --quiet "$@"; }
 
 
+djson() {
+    local out err
+    if ! out=$(ddb); then
+        err "Mongo call failed"
+        return 128
+    fi
+    if [ -z "$out" ]; then
+        err "Mongo replied with empty output"
+        return 64
+    fi
+    if [ "$(e "$out" | jq -r .ok)" != "1" ]; then
+        if ! e "$out" | jq . >/dev/null 2>&1; then
+            err "Mongo didn't output JSON, output follows:"
+            e "$out" | prefix " | "
+            return 32
+        fi >&2
+        errmsg=$(e "$out" | jq -r '.errmsg')
+        code_name=$(e "$out" | jq -r '.codeName')
+        err "Mongo failed with error message: $errmsg (code: ${code_name})"
+        e "$out"
+        return 32
+    fi
+    e "$out"
+    return 0
+}
+
 mongo:db:ls() {
     local out
-    if ! out=$(ddb < <(echo "JSON.stringify(db.adminCommand( { listDatabases: 1 } ))")); then
+    if out=$(djson < <(echo "JSON.stringify(db.adminCommand( { listDatabases: 1 } ))")); then
+        e "$out" | jq -r '.databases[] | .name'
+        return 0
+    else
+        if [ "$(e "$out" | jq -r '.codeName')" == "NotMasterNoSlaveOk" ]; then
+            ## equivalent to having no databases
+            return 0
+        fi
         err "Could not query list of databases."
         return 1
     fi
-    e "$out" | jq -r '.databases[] | .name'
 }