Simple script to update replicating brokers per topic for a Kafka cluster

updateKafkaReplication.sh

#!/bin/bash

    # usage like ./updateKafkaReplication.sh test-replica-update 0,1,2

    TOPIC_NAME=$1
    REPLICAS=$2

    echo "****************************************"
    echo "describe $TOPIC_NAME"
    bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic $TOPIC_NAME

    PARTITION_COUNT=$(eval "bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic $TOPIC_NAME | awk -F '[:\t]' 'NR==1 {print \$4}'")
    echo "Partitions: ${PARTITION_COUNT}"

    JSON_FILE=~/configChanges/${TOPIC_NAME}-update.json
    echo $JSON_FILE
    [ -e $JSON_FILE ] && rm $JSON_FILE

    touch $JSON_FILE

    ((PARTITION_COUNT--))

    printf "{\"version\":1, \"partitions\":[" >> $JSON_FILE

    for i in $(eval echo "{0..$PARTITION_COUNT}");
    do
        if [ $i == $PARTITION_COUNT ]; then
            printf "{\"topic\":\"%s\",\"partition\":%s,\"replicas\":[%s]}" "$TOPIC_NAME" "$i" "$REPLICAS" >> $JSON_FILE
        else
            printf "{\"topic\":\"%s\",\"partition\":%s,\"replicas\":[%s]}," "$TOPIC_NAME" "$i" "$REPLICAS" >> $JSON_FILE
        fi
    done

    printf "]}" >> $JSON_FILE


    echo "****************************************"
    echo "updating $TOPIC_NAME"
    bin/kafka-reassign-partitions.sh --zookeeper localhost:2181 --reassignment-json-file $JSON_FILE --execute

    echo "****************************************"
    echo "describe $TOPIC_NAME"
    bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic $TOPIC_NAME