(end goal) before trying out whether i could eventually read avro data, usng spark stream, out of the Confluent Platform like some described here: Integrating Spark Structured Streaming with the Confluent Schema Registry
I'd to verify whether I could use below command to read them:
$ kafka-avro-console-consumer \
> --topic my-topic-produced-using-file-pulse-xml \
> --from-beginning \
> --bootstrap-server localhost:9092 \
> --property schema.registry.url=http://localhost:8081
I receive this error message, Unknown magic byte
Processed a total of 1 messages
[2020-09-10 12:59:54,795] ERROR Unknown error when running consumer: (kafka.tools.ConsoleConsumer$:76)
org.apache.kafka.common.errors.SerializationException: Unknown magic byte!
[2020-09-10 12:59:54,795] ERROR Unknown error when running consumer: (kafka.tools.ConsoleConsumer$:76)
org.apache.kafka.common.errors.SerializationException: Unknown magic byte!
note, The message can be read like this (using console-consumer instead of avro-console-consumer):
kafka-console-consumer \
--bootstrap-server localhost:9092 --group my-group-console \
--from-beginning \
--topic my-topic-produced-using-file-pulse-xml
The message was produced using confluent connect file-pulse (1.5.2) reading xml file (streamthoughts/kafka-connect-file-pulse)
Please help here:
Did I use the kafka-avro-console-consumer wrong?
I tried "deserializer" properties options described here: https://stackoverflow.com/a/57703102/4582240, did not help
I did not want to be brave to start the spark streaming to read the data yet.
the file-pulse 1.5.2 properties i used are like below added 11/09/2020 for completion.
name=connect-file-pulse-xml
connector.class=io.streamthoughts.kafka.connect.filepulse.source.FilePulseSourceConnector
topic= my-topic-produced-using-file-pulse-xml
tasks.max=1
# File types
fs.scan.filters=io.streamthoughts.kafka.connect.filepulse.scanner.local.filter.RegexFileListFilter
file.filter.regex.pattern=.*\\.xml$
task.reader.class=io.streamthoughts.kafka.connect.filepulse.reader.XMLFileInputReader
force.array.on.fields=sometagNameInXml
# File scanning
fs.cleanup.policy.class=io.streamthoughts.kafka.connect.filepulse.clean.LogCleanupPolicy
fs.scanner.class=io.streamthoughts.kafka.connect.filepulse.scanner.local.LocalFSDirectoryWalker
fs.scan.directory.path=/tmp/kafka-connect/xml/
fs.scan.interval.ms=10000
# Internal Reporting
internal.kafka.reporter.bootstrap.servers=localhost:9092
internal.kafka.reporter.id=connect-file-pulse-xml
internal.kafka.reporter.topic=connect-file-pulse-status
# Track file by name
offset.strategy=name
If you are getting Unknown Magic Byte with the consumer, then the producer didn't use the Confluent AvroSerializer, and might have pushed Avro data that doesn't use the Schema Registry.
Without seeing the Producer code or consuming and inspecting the data in binary format, it is difficult to know which is the case.
The message was produced using confluent connect file-pulse
Did you use value.converter with the AvroConverter class?
Related
I created some dummydata as a Stream in KSQLDB with
VALUE_FORMAT='JSON' TOPIC='MYTOPIC'
The Setup is over Docker-compose. I am running a Kafka Broker, Schema-registry, ksqldbcli, ksqldb-server, zookeeper
Now I want to consume these records from the topic.
My first and last approach was over the commandline with following command
docker run --net=host --rm confluentinc/cp-schema-registry:5.0.0 kafka-avro-console-consumer
--bootstrap-server localhost:29092 --topic DXT --from-beginning --max-messages 10
--property print.key=true --property print.value=true
--value-deserializer io.confluent.kafka.serializers.KafkaAvroDeserializer
--key-deserializer org.apache.kafka.common.serialization.StringDeserializer
But that just returns the error
[2021-04-22 21:45:42,926] ERROR Unknown error when running consumer: (kafka.tools.ConsoleConsumer$:76)
org.apache.kafka.common.errors.SerializationException: Error deserializing Avro message for id -1
Caused by: org.apache.kafka.common.errors.SerializationException: Unknown magic byte!
I also tried it with different use cases in Java Spring but with no prevail. I just cannot consume the created topics.
If I would need to define my own schema, where should I do that and what would be the easiest way because I just created a stream in Ksqldb?
Is there an easy to follow example. I did not specifiy anything else when I created the stream like in the quickstart example on Ksqldb.io. (I added the schema-registry in my deployment)
As I am a noob that is sitting here for almost 10 hours any help would be appreciated.
Edit: I found that pure JSON does not need the Schema-registry with ksqldb. Here.
But how to deserialize it?
If you've written JSON data to the topic then you can read it with the kafka-console-consumer.
The error you're getting (Error deserializing Avro message for id -1…Unknown magic byte!) is because you're using the kafka-avro-console-consumer which attempts to deserialise the topic data as Avro - which it isn't, hence the error.
You can also use PRINT DXT; from within ksqlDB.
I want to send the data sent to the topic to a postgresql-database. So I follow this guide and have configured the properties-file like this:
name=transaction-sink
connector.class=io.confluent.connect.jdbc.JdbcSinkConnector
tasks.max=1
topics=transactions
connection.url=jdbc:postgresql://localhost:5432/db
connection.user=db-user
connection.password=
auto.create=true
insert.mode=insert
table.name.format=transaction
pk.mode=none
I start the connector with
./bin/connect-standalone etc/schema-registry/connect-avro-standalone.properties etc/kafka-connect-jdbc/sink-quickstart-postgresql.properties
The sink-connector is created but does not start due to this error:
Caused by: org.apache.kafka.common.errors.SerializationException: Error deserializing Avro message for id -1
Caused by: org.apache.kafka.common.errors.SerializationException: Unknown magic byte!
The schema is in avro-format and registered and I can send (produce) messages to the topic and read (consume) from it. But I can't seem to sent it to the database.
This is my ./etc/schema-registry/connect-avro-standalone.properties
key.converter=io.confluent.connect.avro.AvroConverter
key.converter.schema.registry.url=http://localhost:8081
value.converter=io.confluent.connect.avro.AvroConverter
value.converter.schema.registry.url=http://localhost:8081
This is a producer feeding the topic using the java-api:
properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaAvroSerializer.class);
properties.put(AbstractKafkaAvroSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, "http://localhost:8081");
try (KafkaProducer<String, Transaction> producer = new KafkaProducer<>(properties)) {
Transaction transaction = new Transaction();
transaction.setFoo("foo");
transaction.setBar("bar");
UUID uuid = UUID.randomUUID();
final ProducerRecord<String, Transaction> record = new ProducerRecord<>(TOPIC, uuid.toString(), transaction);
producer.send(record);
}
I'm verifying data is properly serialized and deserialized using
./bin/kafka-avro-console-consumer --bootstrap-server localhost:9092 \
--property schema.registry.url=http://localhost:8081 \
--topic transactions \
--from-beginning --max-messages 1
The database is up and running.
This is not correct:
The unknown magic byte can be due to a id-field not part of the schema
What that error means that the message on the topic was not serialised using the Schema Registry Avro serialiser.
How are you putting data on the topic?
Maybe all the messages have the problem, maybe only some—but by default this will halt the Kafka Connect task.
You can set
"errors.tolerance":"all",
to get it to ignore messages that it can't deserialise. But if all of them are not correctly Avro serialised this won't help and you need to serialise them correctly, or choose a different Converter (e.g. if they're actually JSON, use the JSONConverter).
These references should help you more:
https://www.confluent.io/blog/kafka-connect-deep-dive-converters-serialization-explained
https://www.confluent.io/blog/kafka-connect-deep-dive-error-handling-dead-letter-queues
http://rmoff.dev/ksldn19-kafka-connect
Edit :
If you are serialising the key with StringSerializer then you need to use this in your Connect config:
key.converter=org.apache.kafka.connect.storage.StringConverter
You can set it at the worker (global property, applies to all connectors that you run on it), or just for this connector (i.e. put it in the connector properties itself, it will override the worker settings)
Summary
When I stream this with the console producer
{"id":1337,"status":"example_topic_1 success"}
I get this in from my filestream consumer
/data/example_topic_1.txt
{id=1337, status=example_topic_1 success}
This is a major problem for me, because the original JSON message cannot be recovered without making assumptions about where the quotes used to be. How can I output the messages to a file, while preserving the quotation marks?
Details
First, I start my file sink connector.
# sh bin/connect-standalone.sh \
> config/worker.properties \
> config/connect-file-sink-example_topic_1.properties
Second, I start console consumer (also built in to Kafka) so that I have easy visual confirmation that the messages are coming through correctly.
# sh bin/kafka-console-consumer.sh \
> --bootstrap-server kafka_broker:9092 \
> --topic example_topic_1
Finally, I start a console producer for sending messages, and I enter a message.
# sh bin/kafka-console-producer.sh \
> --broker-list kafka_broker:9092 \
> --topic example_topic_1
From the console consumer, the message pops out correctly, with quotes.
{"id":1337,"status":"example_topic_1 success"}
But I get this from my the FileStreamSink consumer:
/data/example_topic_1.txt
{id=1337, status=example_topic_1 success}
My Configuration
config/worker.properties
offset.storage.file.filename=/tmp/example.offsets
bootstrap.servers=kafka_broker:9092
offset.flush.interval.ms=10000
key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
value.converter.schemas.enable=false
config/connect-file-sink-example_topic_1.properties
name=file-sink-example_topic_1
connector.class=FileStreamSink
tasks.max=1
file=/data/example_topic_1.txt
topics=example_topic_1
Since you're not actually wanting to parse the JSON data, but just pass it straight through as a lump of text, you need to use the StringConverter:
key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.storage.StringConverter
This article explains more about the nuances of converters: https://rmoff.net/2019/05/08/when-a-kafka-connect-converter-is-not-a-converter/. This shows an example of what you're trying to do, although uses kafkacat in place of the console producer/consumer.
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
The document said add the line compression.codec=gzip in producer.properties to make the message compressed.
However when I open the data file such as: 0000000000000.log I found the data does not look like it is compressed. How should check whether the data in kafka is compressed already?
P.S: Every testing I would stop the Kafka cluster and Zookeeper and deleted all of the data in kafka-logs and Zookeeper,then start the server again and create a new topic.
The Java ProducerConfig class has changed for this config.
public static final String COMPRESSION_TYPE_CONFIG = "compression.type";
I've successfully produced messages with the java client (0.8.2.1) using the ProducerConfig.COMPRESSION_TYPE_CONFIG and it works fine.
Example:
props.put(ProducerConfig.COMPRESSION_TYPE_CONFIG, "gzip");
Or set compression.type=gzip in your server.properties file for the Java client.
Update for cli tool
Read the usage for the command line tools:
chrisblack:kafka:% ./bin/kafka-console-producer.sh
...
--compression-codec [compression-codec] The compression codec: either 'none',
'gzip', 'snappy', or 'lz4'.If
specified without value, then it
defaults to 'gzip'
...
--new-producer Use the new producer implementation.
--producer-property <producer_prop> A mechanism to pass user-defined
properties in the form key=value to
the producer.
--property <prop> A mechanism to pass user-defined
properties in the form key=value to
the message reader. This allows
custom configuration for a user-
defined message reader.
...
Try running a similar command from the shell:
./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test_compression --compression-codec