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#!/bin/bash
# vim: set tabstop=2 expandtab:

set -e

export LANG=en_US.UTF-8

# Comms-less leader determination
# Picks the unit with the lowest id.
am_i_the_leader () {
  # Leader is the lowest unit number and won't be in the
  # list of relation peersa
  units=`relation-list`
  unit_no=`echo $JUJU_UNIT_NAME | cut -d / -f 2`
  for unit in $units; do
    peer_unit_no=`echo $unit | cut -d / -f 2`
    if [ "$peer_unit_no" -lt "$unit_no" ]; then
        return 1
    fi
  done
  return 0
}

# Install cassandra source and install packages
install_cassandra () {
  juju-log "Installing Cassandra"
  # Install the repositories
  echo "deb http://www.apache.org/dist/cassandra/debian 10x main" > /etc/apt/sources.list.d/cassandra.list
  # Add the key
  apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 2B5C1B00
  # Update the repositories
  apt-get update
  # Ensure that cassandra does not startup before we have configured it
  cat > /usr/sbin/policy-rc.d <<EOF
#!/bin/bash
if [ "\$1" == "cassandra" ] && [ "\$2" == "start" ]; then
        exit 101
else
        exit 0
fi
EOF
  chmod a+x /usr/sbin/policy-rc.d
  # Install the package
  apt-get -qq install -y cassandra python-cheetah dnsutils
}

# Update the cassandra environment with the appropriate JMX port
configure_jmx_port () {
  juju-log "Configuring JMX port"
  JMX_PORT=`config-get jmx-port`
  sed -i -e "s/^JMX_PORT=.*/JMX_PORT=\"${JMX_PORT}\"/" /etc/cassandra/cassandra-env.sh
  # Open port ready for expose
  open-port ${JMX_PORT}/TCP
}

get_private_ip () {
  # Make sure that we use the resolvable private address
  # dig deals with both hostnames and ip addresses in a nice
  # way - this has been tested in local and ec2 providers
  # with ec2 and openstack
  dig +short `unit-get private-address` 
}

# Construct the cassandra.yaml file from the appropriate information above
configure_cassandra () {
  juju-log "Configuring Cassandra"
  IP=`get_private_ip`
  CLUSTER_PORT=`config-get cluster-port`
  CLIENT_PORT=`config-get client-port`
  CLUSTER_NAME=`config-get cluster-name`
  AUTO_MEMORY=`config-get auto-memory`
  HEAP_SIZE=`config-get heap-size`
  NEW_GEN_SIZE=`config-get new-gen-size`
  # This needs to 'detect' whether its running in ec2
  # and use the ec2Snitch instead if it is - or we could
  # specify this as a configuration parameter
  sed -i -e "s/^cluster_name:.*/cluster_name: \'${CLUSTER_NAME}\'/" \
         -e "s/\- seeds:.*/\- seeds: \"${IP}\"/" \
         -e "s/^storage_port:.*/storage_port: ${CLUSTER_PORT}/" \
         -e "s/^listen_address:.*/listen_address: ${IP}/" \
         -e "s/^rpc_address:.*/rpc_address: ${IP}/" \
         -e "s/^rpc_port:.*/rpc_port: ${CLIENT_PORT}/" \
         /etc/cassandra/cassandra.yaml
  # Open port ready for expose
  open-port ${CLIENT_PORT}/TCP

  # Configure memory settings as specified in configuration
  if [ "$AUTO_MEMORY" = "False" ]; then
    juju-log "Configuring Manual Memory Setttings"
    sed -i -e "s/^[#]MAX_HEAP_SIZE=.*/MAX_HEAP_SIZE=\"${HEAP_SIZE}\"/" \
           -e "s/^[#]HEAP_NEWSIZE=.*/HEAP_NEWSIZE=\"${NEW_GEN_SIZE}\"/" /etc/cassandra/cassandra-env.sh
  else
    sed -i -e "s/^[#]MAX_HEAP_SIZE=.*/#MAX_HEAP_SIZE=\"${HEAP_SIZE}\"/" \
           -e "s/^[#]HEAP_NEWSIZE=.*/#HEAP_NEWSIZE=\"${NEW_GEN_SIZE}\"/" /etc/cassandra/cassandra-env.sh
  fi 
}

# Service Control Commands
restart_cassandra () {
  juju-log "Restarting Cassandra"
  service cassandra status && service cassandra restart || :
}

start_cassandra() {
  juju-log "Starting Cassandra"
  service cassandra status || service cassandra start
}

stop_cassandra() {
  juju-log "Stopping Cassandra"
  service cassandra stop || :
}

setup_database_interface () {
  juju-log "Setup Cassandra database interface"
  relation-set port="`config-get client-port`"
}

setup_jmx_interface () {
  juju-log "Setup Cassandra JMX interface"
  relation-set port="`config-get jmx-port`"
}

reconfigure_cluster_seeds () {
  juju-log "Reconfiguring cluster seeds"
  # If I'm the initial bootstrap node then I 
  # don't need to be set to auto_bootstrap
  # as everything seeded off me anyway
  INIT_SEED=$(echo ${JUJU_UNIT_NAME} | sed s,.*/,,)
  [ ${INIT_SEED} == "0" ] && return 0

  # If node is not set to autoboostrap then set it to be
  AUTO=$(grep '^auto_bootstrap: true$' /etc/cassandra/cassandra.yaml || true)
  if [ -z "${AUTO}" ]; then
    # Enable bootstrap for this node.
    sed -i -e "s/^auto_bootstrap:.*/auto_bootstrap: true/" \
        /etc/cassandra/cassandra.yaml
  fi
  # This needs careful handling - to start with we need 
  # an initial seed - which should not auto_boostrap
  # Build up list of seeds - these are used when new
  # nodes startup to build the ring.
  for node in `relation-list`
  do
    NODE_HOSTNAME=`relation-get private-address ${node}`
    [ -z ${TMP_SEEDS} ] && TMP_SEEDS=${NODE_HOSTNAME} || TMP_SEEDS="${TMP_SEEDS},${NODE_HOSTNAME}"
  done
  sed -i -e "s/\- seeds:.*/\- seeds: \"${TMP_SEEDS}\"/" /etc/cassandra/cassandra.yaml
  # Restart to pickup changes - this only really needs to 
  # happen for NEW nodes in the ring - not existing ones 
  # which have already auto_bootstrapped
  if [ -z "${AUTO}" ]; then
    restart_cassandra
  fi
  juju-log "$JUJU_REMOTE_UNIT modified its settings or departed"
}

remove_down_nodes () {
  if am_i_the_leader; then
    sleep 30
    juju-log "Removing tokens for nodes which are marked 'Down'"
    PRIVATE_IP=`get_private_ip`
    tokens=`nodetool -h $PRIVATE_IP ring | grep Down | awk '{ print $9 }'`
    for token in $tokens; do
      juju-log "Removing token $token from the ring"
      nodetool -h $PRIVATE_IP removetoken $token
    done
  fi
}

decommission_node () {
  juju-log "Decommissioning node - this may take some time..."
  nodetool -h `get_private_ip` decommission
}

# Actual processing
COMMAND=`basename $0`

case $COMMAND in
  install)
    # Install cassandra first run only
    [[ -d /usr/share/cassandra ]] || install_cassandra
    # Update the cassandra environment with the appropriate JMX port
    configure_jmx_port 
    # Construct the cassandra.yaml file from the appropriate information above
    configure_cassandra 
    ;;
  config-changed)
    # Update the cassandra environment with the appropriate JMX port
    configure_jmx_port 
    # Construct the cassandra.yaml file from the appropriate information above
    configure_cassandra
    # Restart as required
    restart_cassandra
    ;;
  upgrade-charm)
    juju-log "Updating this charm - currently no-op"
    ;;
  start)
    start_cassandra
    ;;
  stop)
    stop_cassandra
    ;;
  database-relation-joined)
    setup_database_interface 
    ;;
  cluster-relation-joined)
    juju-log "Joining cassandra cluster..."
    ;;
  cluster-relation-changed)
    reconfigure_cluster_seeds
    ;;
  cluster-relation-departed)
    reconfigure_cluster_seeds
    remove_down_nodes
    ;;
  jmx-relation-joined)
    setup_jmx_interface
    ;;
  *)
    juju-log "Command not recognised"
    ;;
esac