1 files changed, 73 insertions, 0 deletions
diff --git a/zookeeper/init/on-start.sh b/zookeeper/init/on-start.sh
new file mode 100755
index 0000000..392b82a
--- /dev/null
+++ b/zookeeper/init/on-start.sh
@@ -0,0 +1,73 @@
+#! /bin/bash
+
+# Copyright 2016 The Kubernetes Authors All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This script configures zookeeper cluster member ship for version of zookeeper
+# >= 3.5.0. It should not be used with the on-change.sh script in this example.
+# As of April-2016 is 3.4.8 is the latest stable.
+
+# Both /opt and /tmp/zookeeper are assumed to be volumes shared with the parent.
+CFG=/opt/zookeeper/conf/zoo.cfg.dynamic
+CFG_BAK=/opt/zookeeper/conf/zoo.cfg.bak
+MY_ID_FILE=/tmp/zookeeper/myid
+HOSTNAME=$(hostname)
+
+while read -ra LINE; do
+    PEERS=("${PEERS[@]}" $LINE)
+done
+
+# Don't add the first member as an observer
+if [ ${#PEERS[@]} -eq 1 ]; then
+    # We need to write our index in this list of servers into MY_ID_FILE.
+    # Note that this may not always coincide with the hostname id.
+    echo 1 > "${MY_ID_FILE}"
+    echo "server.1=${PEERS[0]}:2888:3888;2181" > "${CFG}"
+    # TODO: zkServer-initialize is the safe way to handle changes to datadir
+    # because simply starting will create a new datadir, BUT if the user changed
+    # pod template they might end up with 2 datadirs and brief split brain.
+    exit
+fi
+
+# Every subsequent member is added as an observer and promoted to a participant
+echo "" > "${CFG_BAK}"
+i=0
+for peer in "${PEERS[@]}"; do
+    let i=i+1
+    if [[ "${peer}" == *"${HOSTNAME}"* ]]; then
+      MY_ID=$i
+      MY_NAME=${peer}
+      echo $i > "${MY_ID_FILE}"
+      echo "server.${i}=${peer}:2888:3888:observer;2181" >> "${CFG_BAK}"
+    else
+      echo "server.${i}=${peer}:2888:3888:participant;2181" >> "${CFG_BAK}"
+    fi
+done
+
+# Once the dynamic config file is written it shouldn't be modified, so the final
+# reconfigure needs to happen through the "reconfig" command.
+cp ${CFG_BAK} ${CFG}
+
+# TODO: zkServer-initialize is the safe way to handle changes to datadir
+# because simply starting will create a new datadir, BUT if the user changed
+# pod template they might end up with 2 datadirs and brief split brain.
+/opt/zookeeper/bin/zkServer.sh start
+
+# TODO: We shouldn't need to specify the address of the master as long as
+# there's quorum. According to the docs the new server is just not allowed to
+# vote, it's still allowed to propose config changes, and it knows the
+# existing members of the ensemble from *its* config. This works as expected,
+# but we should correlate with more satisfying empirical evidence.
+/opt/zookeeper/bin/zkCli.sh reconfig -add "server.$MY_ID=$MY_NAME:2888:3888:participant;2181"
+/opt/zookeeper/bin/zkServer.sh stop