start-kafka.sh

#!/bin/bash

if [[ -z "$KAFKA_PORT" ]]; then
    export KAFKA_PORT=9092
fi
# if [[ -z "$KAFKA_ADVERTISED_PORT" ]]; then
#     export KAFKA_ADVERTISED_PORT=$(docker port `hostname` $KAFKA_PORT | sed -r "s/.*:(.*)/\1/g")
# fi
if [[ -z "$KAFKA_BROKER_ID" ]]; then
    # By default auto allocate broker ID
    export KAFKA_BROKER_ID=-1
fi
if [[ -z "$KAFKA_LOG_DIRS" ]]; then
    export KAFKA_LOG_DIRS="/kafka/kafka-logs-$HOSTNAME"
fi
# if [[ -z "$KAFKA_ZOOKEEPER_CONNECT" ]]; then
#     export KAFKA_ZOOKEEPER_CONNECT=$(env | grep ZK.*PORT_2181_TCP= | sed -e 's|.*tcp://||' | paste -sd ,)
# fi

if [[ -n "$KAFKA_HEAP_OPTS" ]]; then
    sed -r -i "s/(export KAFKA_HEAP_OPTS)=\"(.*)\"/\1=\"$KAFKA_HEAP_OPTS\"/g" $KAFKA_HOME/bin/kafka-server-start.sh
    unset KAFKA_HEAP_OPTS
fi

if [[ ! -z "$ADV_HOST" ]]; then
	export KAFKA_ADVERTISED_HOST_NAME=$ADV_HOST
fi

if [[ -z "$KAFKA_ADVERTISED_HOST_NAME" && -n "$HOSTNAME_COMMAND" ]]; then
    export KAFKA_ADVERTISED_HOST_NAME=$(eval $HOSTNAME_COMMAND)
fi

# Allow specification of log retention policies
if [ ! -z "$LOG_RETENTION_HOURS" ]; then
    echo "log retention hours: $LOG_RETENTION_HOURS"
    sed -r -i "s/(log.retention.hours)=(.*)/\1=$LOG_RETENTION_HOURS/g" $KAFKA_HOME/config/server.properties
fi

if [ ! -z "$LOG_RETENTION_BYTES" ]; then
    echo "log retention bytes: $LOG_RETENTION_BYTES"
    sed -r -i "s/#(log.retention.bytes)=(.*)/\1=$LOG_RETENTION_BYTES/g" $KAFKA_HOME/config/server.properties
fi

# Enable/disable auto creation of topics
if [ ! -z "$AUTO_CREATE_TOPICS" ]; then
    echo "auto.create.topics.enable: $AUTO_CREATE_TOPICS"
    echo "auto.create.topics.enable=$AUTO_CREATE_TOPICS" >> $KAFKA_HOME/config/server.properties
fi

if [ ! -z "$KAFKA_STANDALONE" ]; then
	echo "offsets.topic.replication.factor=1" >> $KAFKA_HOME/config/server.properties
fi

for VAR in `env`
do
  if [[ $VAR =~ ^KAFKA_ && ! $VAR =~ ^KAFKA_HOME ]]; then
    kafka_name=`echo "$VAR" | sed -r "s/KAFKA_(.*)=.*/\1/g" | tr '[:upper:]' '[:lower:]' | tr _ .`
    env_var=`echo "$VAR" | sed -r "s/(.*)=.*/\1/g"`
    if egrep -q "(^|^#)$kafka_name=" $KAFKA_HOME/config/server.properties; then
        sed -r -i "s@(^|^#)($kafka_name)=(.*)@\2=${!env_var}@g" $KAFKA_HOME/config/server.properties #note that no config values may contain an '@' char
    else
        echo "$kafka_name=${!env_var}" >> $KAFKA_HOME/config/server.properties
    fi
  fi
done

# Generate the config only if it doesn't exist
if [ ! -f "$ZOO_CONF_DIR/zoo.cfg" ]; then
    CONFIG="$ZOO_CONF_DIR/zoo.cfg"

    echo "clientPort=$ZOO_PORT" >> "$CONFIG"
    echo "dataDir=$ZOO_DATA_DIR" >> "$CONFIG"
    echo "dataLogDir=$ZOO_DATA_LOG_DIR" >> "$CONFIG"

	 if [ ! -z "$KAFKA_ADVERTISED_HOST_NAME" ]; then
		 echo "advertised.host.name=$KAFKA_ADVERTISED_HOST_NAME"  >> "$CONFIG"
	 fi

    echo 'tickTime=2000' >> "$CONFIG"
    echo 'initLimit=5' >> "$CONFIG"
    echo 'syncLimit=2' >> "$CONFIG"

    for server in $ZOO_SERVERS; do
        echo "$server" >> "$CONFIG"
    done

fi

# Write myid only if it doesn't exist
if [ ! -f "$ZOO_DATA_DIR/myid" ]; then
    echo "${ZOO_MY_ID:-1}" > "$ZOO_DATA_DIR/myid"
fi

if [[ -n "$CUSTOM_INIT_SCRIPT" ]] ; then
  eval $CUSTOM_INIT_SCRIPT
fi


KAFKA_PID=0

# see https://medium.com/@gchudnov/trapping-signals-in-docker-containers-7a57fdda7d86#.bh35ir4u5
term_handler() {
  echo 'Stopping Kafka....'
  if [ $KAFKA_PID -ne 0 ]; then
    kill -s TERM "$KAFKA_PID"
    wait "$KAFKA_PID"
  fi
  echo 'Kafka stopped.'
  exit
}


# Capture kill requests to stop properly
trap "term_handler" SIGHUP SIGINT SIGTERM

supervisord -n &
KAFKA_PID=$!

wait