Checking that Atlas is up-to-date

#!/usr/bin/env bash

# Determine Atlas keytab path.
ATLAS_KT=$(find / -wholename "*atlas-ATLAS_SERVER/atlas.keytab" 2>/dev/null | head -n 1)

# Setup required configuration files if needed.
if [[ ! -f jaas.conf ]]; then
	ATLAS_PRINCIPAL=$(klist -kt "${ATLAS_KT}" | grep -o -m 1 "atlas\/\S*")
	printf "KafkaClient {
	\tcom.sun.security.auth.module.Krb5LoginModule required
	\tuseKeyTab=true
	\tkeyTab=\"%s\"
	\tprincipal=\"%s\";\n};\n" "${ATLAS_KT}" "${ATLAS_PRINCIPAL}" > jaas.conf
fi

if [[ ! -f client.config ]]; then
	printf "security.protocol=SASL_SSL\nsasl.kerberos.service.name=kafka\n" > client.config
fi

# Determine the Kafka bootstrap server to use.
KAFKA_SERVER=$(grep --line-buffered -oP "atlas.kafka.bootstrap.servers=\K.*" \
	/etc/atlas/conf/atlas-application.properties | awk -F',' '{print $1}')

# Export Kafka-specific environment variables.
export KAFKA_HEAP_OPTS="-Xms512m -Xmx1g"
export KAFKA_OPTS="-Djava.security.auth.login.config=${PWD}/jaas.conf"

# Kinit into Atlas keytab as Atlas user.
kinit -kt "$ATLAS_KT" "atlas/$(hostname -f)" 2>/dev/null

# Obtain Atlas lineage information.
LINEAGE_INFO=$(/opt/cloudera/parcels/CDH/lib/kafka/bin/kafka-consumer-groups.sh \
	--bootstrap-server "${KAFKA_SERVER}" --describe --group atlas \
	--command-config="${PWD}/client.config" 2>/dev/null \
	| awk '{print $2, $6}')

if [[ -z "$LINEAGE_INFO" ]]; then
	echo "*ERROR*: Unable to get lineage info for Atlas. Please look at the created configuration files to make sure they look correct."
	exit 1
fi

# Parse lineage information and determine if Atlas is out of date.
LINEAGE_LAG_VALS=($LINEAGE_INFO)
NUM_LAG_VALS=${#LINEAGE_LAG_VALS[@]}
OUT_OF_DATE_TOPICS=""
for (( i = 2; i < ${NUM_LAG_VALS}; i += 2 )); do
	if [[ ${LINEAGE_LAG_VALS[${i} + 1]} != '-' && ${LINEAGE_LAG_VALS[${i} + 1]} != '0' ]]; then
    	OUT_OF_DATE_TOPICS="${OUT_OF_DATE_TOPICS}${LINEAGE_LAG_VALS[$i]}, "
	fi
done

if [[ -z "$OUT_OF_DATE_TOPICS" ]]; then
	echo "Atlas is up to date! Feel free to continue with the migration."
else
	echo "The following Atlas topics are not up to date: ${OUT_OF_DATE_TOPICS%??}!"
	echo "Please wait until Atlas is entirely up to date before continuing with the migration."
fi