I'm working on an application to process logs with Spark and I thought to use Kafka as a way to stream the data from the log file. Basically I have a single log file (on the local file system) which is continuously updated with new logs, and Kafka Connect seems to be the perfect solution to get the data from the file along with the new appended lines.
I'm starting the servers with their default configurations with the following commands:
Zookeeper server:
zookeeper-server-start.sh config/zookeeper.properties
zookeeper.properties
dataDir=/tmp/zookeeper
clientPort=2181
maxClientCnxns=0
Kafka server:
kafka-server-start.sh config/server.properties
server.properties
broker.id=0
log.dirs=/tmp/kafka-logs
zookeeper.connect=localhost:2181
[...]
Then I created the topic 'connect-test':
kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic connect-test
And finally I run the Kafka Connector:
connect-standalone.sh config/connect-standalone.properties config/connect-file-source.properties
connect-standalone.properties
bootstrap.servers=localhost:9092
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=true
internal.key.converter=org.apache.kafka.connect.json.JsonConverter
internal.value.converter=org.apache.kafka.connect.json.JsonConverter
internal.key.converter.schemas.enable=false
internal.value.converter.schemas.enable=false
offset.storage.file.filename=/tmp/connect.offsets
offset.flush.interval.ms=10000
connect-file-source.properties
name=my-file-connector
connector.class=FileStreamSource
tasks.max=1
file=/data/users/zamara/suivi_prod/app/data/logs.txt
topic=connect-test
At first I tested the connector by running a simple console consumer:
kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic connect-test --from-beginning
Everything was working perfectly, the consumer was receiving the logs from the file and as I was adding logs the consumer kept updating with the new ones.
(Then I tried Spark as a "consumer" following this guide: https://spark.apache.org/docs/2.2.0/streaming-kafka-0-8-integration.html#approach-2-direct-approach-no-receivers and it was still fine)
After this, I removed some of the logs from the log file and changed the topic (I deleted the 'connect-test' topic, created another one and edited the connect-file-source.properties with the new topic).
But now the connector doesn't work the same way anymore. When using the console consumer, I only get the logs that were already in the file and every new line I add is ignored. Maybe changing the topic (and/or modifying the data from the log file) without changing the connector name broke something in Kafka...
This is what Kafka Connect does with my topic 'new-topic' and connector 'new-file-connector', :
[2018-05-16 15:06:42,454] INFO Created connector new-file-connector (org.apache.kafka.connect.cli.ConnectStandalone:104)
[2018-05-16 15:06:42,487] INFO Cluster ID: qjm74WJOSomos3pakXb2hA (org.apache.kafka.clients.Metadata:265)
[2018-05-16 15:06:42,522] INFO Updated PartitionLeaderEpoch. New: {epoch:0, offset:0}, Current: {epoch:-1, offset:-1} for Partition: new-topic-0. Cache now contains 0 entries. (kafka.server.epoch.LeaderEpochFileCache)
[2018-05-16 15:06:52,453] INFO WorkerSourceTask{id=new-file-connector-0} Committing offsets (org.apache.kafka.connect.runtime.WorkerSourceTask:328)
[2018-05-16 15:06:52,453] INFO WorkerSourceTask{id=new-file-connector-0} flushing 0 outstanding messages for offset commit (org.apache.kafka.connect.runtime.WorkerSourceTask:345)
[2018-05-16 15:06:52,458] INFO WorkerSourceTask{id=new-file-connector-0} Finished commitOffsets successfully in 5 ms (org.apache.kafka.connect.runtime.WorkerSourceTask:427)
[2018-05-16 15:07:02,459] INFO WorkerSourceTask{id=new-file-connector-0} Committing offsets (org.apache.kafka.connect.runtime.WorkerSourceTask:328)
[2018-05-16 15:07:02,459] INFO WorkerSourceTask{id=new-file-connector-0} flushing 0 outstanding messages for offset commit (org.apache.kafka.connect.runtime.WorkerSourceTask:345)
[2018-05-16 15:07:12,459] INFO WorkerSourceTask{id=new-file-connector-0} Committing offsets (org.apache.kafka.connect.runtime.WorkerSourceTask:328)
[2018-05-16 15:07:12,460] INFO WorkerSourceTask{id=new-file-connector-0} flushing 0 outstanding messages for offset commit (org.apache.kafka.connect.runtime.WorkerSourceTask:345)
(it keeps flushing 0 outstanding messages even after appending new lines to the file)
So I tried to start over: I deleted the /tmp/kafka-logs directory, the /tmp/connect.offset file, and used a brand new topic name, connector name and log file, just in case. But still, the connector ignores new logs... I even tried to delete my kafka, re-extract it from the archive and run the whole process again (in case something changed in Kafka), but no success.
I'm confused as to where the problem is, any help would be appreciated !
Per docs:
The FileStream Connector examples are intended to show how a simple connector runs for those first getting started with Kafka Connect as either a user or developer. It is not recommended for production use.
I would use something like Filebeat (with its Kafka output) instead for ingesting logs into Kafka. Or kafka-connect-spooldir if your logs are not appended to directly but are standalone files placed in a folder for ingest.
Kafka Connect does not "watch" or "tail" a file. I don't believe it is documented anywhere that it does do that.
I would say it is even less useful for reading active logs than using Spark Streaming to watch a folder. Spark will "recognize" newly created files. Kafka Connect FileStreamSource must point at a single pre-existing, immutable file.
To get Spark to work with active logs, you would need something that does "log rotation" - that is, when the file reaches a max size or a condition such as the end of a time period (say a day), then this process would move the active log to the directory Spark is watching, then it handles starting a new log file for your application to continue to write to.
If you want files to be actively watched and ingested into Kafka then Filebeat, Fluentd, or Apache Flume can be used.
Related
I have updated below properties file according to my requirement
connect-standalone.properties
connect-file-source.properties
connect-file-sink.properties
The Kafka Connect process start and the source connector read lines and write these as messages to the test_topic but messages are not written in test.sink.txt
bin/connect-standalone.sh config/connect-standalone.properties config/connect-file-source.properties config/connect-file-sink.properties
How do I got all details of kafka server like kafka topic names, partitions, groups etc before shutting kafka server. And use this information to ready new kafka server ?
Is there any option for this type of backup ?
Kafka uses zookeeper to store metadata.
If you want to get overview of all topics, partitions or consumer groups, you can collect from zookeeper shell.
Example : to collect the consumer groups, use ls /consumers as following:
kafka % bin/zookeeper-shell.sh localhost:2181 <<< "ls /consumers"
Connecting to localhost:2181
Welcome to ZooKeeper!
JLine support is disabled
WATCHER::
WatchedEvent state:SyncConnected type:None path:null
[console-consumer-66605, console-consumer-84350, console-consumer-9354, console-consumer-28182, console-consumer-61085, console-consumer-67016, console-consumer-81504, console-consumer-47711, console-consumer-87328, console-consumer-27998, console-consumer-73330, console-consumer-73529, console-consumer-17369, console-consumer-75626, console-consumer-6886, console-consumer-11693]
Similarly for collecting topic names, use :
ls /brokers/topics
For collecting number of partitions :
ls /brokers/topics/<topic name>/partitions
You can export these details for some file and use for next server
i'm trying to start a consumer using Apache Kafka, it used to work well, but i had to format my pc and reinstall everything again, and now when trying to run this:
bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning
this is what i'm getting:
Missing required argument "[zookeeper]"
Option Description
------ -----------
--blacklist <blacklist> Blacklist of topics to exclude from
consumption.
--bootstrap-server <server to connect
to>
--consumer.config <config file> Consumer config properties file.
--csv-reporter-enabled If set, the CSV metrics reporter will
be enabled
--delete-consumer-offsets If specified, the consumer path in
zookeeper is deleted when starting up
--formatter <class> The name of a class to use for
formatting kafka messages for
display. (default: kafka.tools.
DefaultMessageFormatter)
--from-beginning If the consumer does not already have
an established offset to consume
from, start with the earliest
message present in the log rather
than the latest message.
--key-deserializer <deserializer for
key>
--max-messages <Integer: num_messages> The maximum number of messages to
consume before exiting. If not set,
consumption is continual.
--metrics-dir <metrics directory> If csv-reporter-enable is set, and
this parameter isset, the csv
metrics will be outputed here
--new-consumer Use the new consumer implementation.
--property <prop>
--skip-message-on-error If there is an error when processing a
message, skip it instead of halt.
--timeout-ms <Integer: timeout_ms> If specified, exit if no message is
available for consumption for the
specified interval.
--topic <topic> The topic id to consume on.
--value-deserializer <deserializer for
values>
--whitelist <whitelist> Whitelist of topics to include for
consumption.
--zookeeper <urls> REQUIRED: The connection string for
the zookeeper connection in the form
host:port. Multiple URLS can be
given to allow fail-over.
my guess is that there's some kind of problem with the zookeeper connection port, because it's telling me to specify the port which zookeeper has to use to get connected to kafka. I'm not sure of this though, and don't know how to figure out the port to specify if this was the problem. Any suggestions??
Thanks in advance for the help
It looks like you are using an old version of the Kafka tools that requires to set --new-consumer if you want to directly connect to the brokers.
I'd recommend picking a recent version of Kafka so you only need to specify --bootstrap-server like in your example: http://kafka.apache.org/downloads
I have a Kafka Streams application with messages up to 10MiB. I want to persist these messages in a state store, but Kafka Streams fails to produce to the internal changelog topic:
2017-11-17 08:36:19,792 ERROR RecordCollectorImpl - task [4_5] Error sending record to topic appid-statestorename-state-store-changelog. No more offsets will be recorded for this task and the exception will eventually be thrown
org.apache.kafka.common.errors.RecordTooLargeException: The request included a message larger than the max message size the server will accept.
2017-11-17 08:36:20,583 ERROR StreamThread - stream-thread [StreamThread-1] Failed while executing StreamTask 4_5 due to flush state:
By adding some logging, it looks like the default max.message.bytes setting of an internal topic is 1MiB.
The default max.message.bytes for the cluster is set to 50MiB.
Is it possible to tweak the configuration of internal topics of Kafka Streams applications?
A work-around is to start the streams application, let it create the topics, and afterwards alter the topic config. But this feels like a dirty hack.
./kafka-topics.sh --zookeeper ... \
--alter --topic appid-statestorename-state-store-changelog \
--config max.message.bytes=10485760
Kafka 1.0 allows to specify custom topic properties for internal topics via StreamsConfig.
You prefix those configs with "topic." and can use any configs as defined in TopicConfig.
See the original KIP for more details:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-173%3A+Add+prefix+to+StreamsConfig+to+enable+setting+default+internal+topic+configs
I am running Kafka 0.10.0 on CDH 5.9, cluster is kerborized.
What I am trying to do is to write messages from a remote machine to my Kafka broker.
The cluster (where Kafka is installed) has internal as well as external IP addresses.
The machines' hostnames within the cluster get resolved to the private IPs, the remote machine resolves the same hostnames to the public IP addreses.
I opened the necessary port 9092 (I am using SASL_PLAINTEXT protocol) from remote machine to Kafka Broker, verified that using telnet.
First Step - in addition to the standard properties for the Kafka Broker, I configured the following:
listeners=SASL_PLAINTEXT://0.0.0.0:9092
advertised.listeners=SASL_PLAINTEXT://<hostname>:9092
I am able to start the console consumer with
kafka-console-consumer --new consumer --topic <topicname> --from-beginning --bootstrap-server <hostname>:9092 --consumer.config consumer.properties
I am able to use my custom producer from another machine within the cluster.
Relevant excerpt of producer properties:
security.protocol=SASL_PLAINTEXT
bootstrap.servers=<hostname>:9092
I am not able to use my custom producer from the remote machine:
Exception org.apache.kafka.common.errors.TimeoutException: Batch containing 1 record(s) expired due to timeout while requesting metadata from brokers for <topicname>-<partition>
using the same producer properties. I am able to telnet the Kafka Broker from the machine and /etc/hosts includes hostnames and public IPs.
Second Step - I modified server.properties:
listeners=SASL_PLAINTEXT://0.0.0.0:9092
advertised.listeners=SASL_PLAINTEXT://<kafkaBrokerInternalIP>:9092
consumer & producer within the same cluster still run fine (bootstrap
servers are now the internal IP with port 9092)
as expected remote producer fails (but that is obvious given that it
is not aware of the internal IP addresses)
Third Step - where it gets hairy :(
listeners=SASL_PLAINTEXT://0.0.0.0:9092
advertised.listeners=SASL_PLAINTEXT://<kafkaBrokerPublicIP>:9092
starting my consumer with
kafka-console-consumer --new-consumer --topic <topicname> --from-beginning --bootstrap-server <hostname>:9092 --consumer.config consumer.properties
gives me a warning, but I don't think this is right...
WARN clients.NetworkClient: Error while fetching metadata with correlation id 1 : {<topicname>=LEADER_NOT_AVAILABLE}
starting my consumer with
kafka-console-consumer --new-consumer --topic <topicname> --from-beginning --bootstrap-server <KafkaBrokerPublicIP>:9092 --consumer.config consumer.properties
just hangs after those log messages:
INFO utils.AppInfoParser: Kafka version : 0.10.0-kafka-2.1.0
INFO utils.AppInfoParser: Kafka commitId : unknown
seems like it cannot find a coordinator as in the normal flow this would be the next log:
INFO internals.AbstractCoordinator: Discovered coordinator <hostname>:9092 (id: <someNumber> rack: null) for group console-consumer-<someNumber>.
starting the producer on a cluster node with bootstrap.servers=:9092
I observe the same as with the producer:
WARN NetworkClient:600 - Error while fetching metadata with correlation id 0 : {<topicname>=LEADER_NOT_AVAILABLE}
starting the producer on a cluster node with bootstrap.servers=:9092 I get
org.apache.kafka.common.errors.TimeoutException: Failed to update metadata after 60000 ms.
starting the producer on my remote machine with either bootstrap.servers=:9092 or bootstrap.servers=:9092 I get
NetworkClient:600 - Error while fetching metadata with correlation id 0 : {<topicname>=LEADER_NOT_AVAILABLE}
I have been struggling for the past three days to get this to work, however I am out of ideas :/ My understanding is that advertised.hostnames serves for exactly this purpose, however either I am doing something wrong, or there is something wrong in the machine setup.
Any hints are very much appreciated!
I met this issue recently.
In my case , I enabled Kafka ACL, and after disable it by comment this 2 configuration, the problem worked around.
authorizer.class.name=kafka.security.auth.SimpleAclAuthorizer
super.users=User:kafka
And an thread may help you I think:
https://gist.github.com/jorisdevrede/a7933a99251452bb1867
What mentioned in it at the end:
If you only use a SASL_PLAINTEXT listener on the Kafka Broker, you
have to make sure that you have set the
security.inter.broker.protocol=SASL_PLAINTEXT too, otherwise you will
get a LEADER_NOT_AVAILABLE error in the client.