KafkaConsumer: how to increase log level? - apache-kafka

Question

When I run my Java application and instantiate the KafkaConsumer object (fed with the minimum required properties: key and value deserializer and group_id); I see lots of INFO messages on the StdOut (If I provide unsupported properties, I also see WARNING messages).
I want to see when fetch events take place. I assume that by increasing the loglevel to DEBUG I will be able to see that. Unfortunately, I am not able to increase it.
I tried to feed the log4j.properties file in multiple ways (placing the file at specific paths and also passing it as parameter (-Dlog4j.configuration). The output remains the same.
cd /Users/user/git/kafka/toys; JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home "/Applications/NetBeans/NetBeans 8.2.app/Contents/Resources/NetBeans/java/maven/bin/mvn" "-Dexec.args=-classpath %classpath ch.demo.toys.CarthusianConsumer" -Dexec.executable=/Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home/bin/java -Dexec.classpathScope=runtime -DskipTests=true org.codehaus.mojo:exec-maven-plugin:1.2.1:exec
Running NetBeans Compile On Save execution. Phase execution is skipped and output directories of dependency projects (with Compile on Save turned on) will be used instead of their jar artifacts.
Scanning for projects...
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Building toys 1.0-SNAPSHOT
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--- exec-maven-plugin:1.2.1:exec (default-cli) # toys ---
Jul 10, 2019 2:52:00 PM org.apache.kafka.common.config.AbstractConfig logAll
INFO: ConsumerConfig values:
allow.auto.create.topics = true
auto.commit.interval.ms = 5000
auto.offset.reset = earliest
bootstrap.servers = [kafka-server:9090, kafka-server:9091, kafka-server:9092]
check.crcs = true
client.dns.lookup = default
client.id =
client.rack =
connections.max.idle.ms = 540000
default.api.timeout.ms = 60000
enable.auto.commit = true
exclude.internal.topics = true
fetch.max.bytes = 52428800
fetch.max.wait.ms = 500
fetch.min.bytes = 1
group.id = carthusian-consumer
group.instance.id = null
heartbeat.interval.ms = 3000
interceptor.classes = []
internal.leave.group.on.close = true
isolation.level = read_uncommitted
key.deserializer = class org.apache.kafka.common.serialization.IntegerDeserializer
max.partition.fetch.bytes = 1048576
max.poll.interval.ms = 300000
max.poll.records = 100000
metadata.max.age.ms = 300000
metric.reporters = []
metrics.num.samples = 2
metrics.recording.level = DEBUG
metrics.sample.window.ms = 30000
partition.assignment.strategy = [class org.apache.kafka.clients.consumer.RangeAssignor]
receive.buffer.bytes = 65536
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retry.backoff.ms = 100
sasl.client.callback.handler.class = null
sasl.jaas.config = null
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.login.callback.handler.class = null
sasl.login.class = null
sasl.login.refresh.buffer.seconds = 300
sasl.login.refresh.min.period.seconds = 60
sasl.login.refresh.window.factor = 0.8
sasl.login.refresh.window.jitter = 0.05
sasl.mechanism = GSSAPI
security.protocol = PLAINTEXT
send.buffer.bytes = 131072
session.timeout.ms = 10000
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
ssl.endpoint.identification.algorithm = https
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLS
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
value.deserializer = class org.apache.kafka.common.serialization.StringDeserializer
Jul 10, 2019 2:52:01 PM org.apache.kafka.common.utils.AppInfoParser$AppInfo <init>
INFO: Kafka version: 2.3.0
Jul 10, 2019 2:52:01 PM org.apache.kafka.common.utils.AppInfoParser$AppInfo <init>
INFO: Kafka commitId: fc1aaa116b661c8a
Jul 10, 2019 2:52:01 PM org.apache.kafka.common.utils.AppInfoParser$AppInfo <init>
INFO: Kafka startTimeMs: 1562763121219
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.KafkaConsumer subscribe
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Subscribed to topic(s): sequence
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.Metadata update
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Cluster ID: REIXp5FySKGPHlRyfTALLQ
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.AbstractCoordinator$FindCoordinatorResponseHandler onSuccess
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Discovered group coordinator kafka-tds:9091 (id: 2147483646 rack: null)
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.ConsumerCoordinator onJoinPrepare
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Revoking previously assigned partitions []
Revoke event: []
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.AbstractCoordinator sendJoinGroupRequest
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] (Re-)joining group
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.AbstractCoordinator sendJoinGroupRequest
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] (Re-)joining group
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.AbstractCoordinator$1 onSuccess
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Successfully joined group with generation 96
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.ConsumerCoordinator onJoinComplete
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Setting newly assigned partitions: sequence-1, sequence-0
Assignment event: [sequence-1, sequence-0]
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.SubscriptionState lambda$requestOffsetReset$3
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Seeking to EARLIEST offset of partition sequence-1
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.SubscriptionState lambda$requestOffsetReset$3
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Seeking to EARLIEST offset of partition sequence-0
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.SubscriptionState maybeSeekUnvalidated
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Resetting offset for partition sequence-0 to offset 0.
Jul 10, 2019 2:52:01 PM org.apache.kafka.clients.consumer.internals.SubscriptionState maybeSeekUnvalidated
INFO: [Consumer clientId=consumer-1, groupId=carthusian-consumer] Resetting offset for partition sequence-1 to offset 0.
Loaded 9804 records from [sequence-0] partitions
Loaded 9804 records from [sequence-1] partitions
Loaded 9799 records from [sequence-0] partitions
Loaded 9799 records from [sequence-1] partitions
Loaded 9799 records from [sequence-0] partitions
Loaded 9799 records from [sequence-1] partitions
Loaded 9799 records from [sequence-0] partitions
Loaded 9799 records from [sequence-1] partitions
Loaded 9799 records from [sequence-0] partitions

Answer 1

Solved by placing the following (simple) log4j.properties under src/main/resources and running the app straight from console (rather than from the IDE). Fetching messages are now shown.
# Root logger option
log4j.rootLogger=DEBUG, stdout
# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1} - %m%n
At the moment I do not know which class is generating the messages I am looking for, hence the DEBUG setting on the rootLogger.