kafka関連のメモについて
以下の図が非常に理解に役立つ
要点だけ記述しておくと
- producerとconsumerはzookeeperからbroker情報を取得する
- brokerはzookeeperにtopicなどの情報を登録する
- producerはbrokerにメッセージの送信を行う
- consumerはbrokerからメッセージの取得を行う
tgzパッケージをdownloadしてスタンドアロンですぐに動作確認することができます。
次の資料を元にして確認を行った。
パッケージ取得後、次のようにして展開してディレクトリに移動する。
$ tar xzvf kafka_2.11-0.10.1.0.tgz
$ cd kafka_2.11-0.10.1.0
余談だが、このディレクトリの中からbin/中のコマンドを何度も呼び出すのでscreenやtmuxなどを動かして実行したほうがいいかもしれない。
まずはzookeeperを動かす。
$ bin/zookeeper-server-start.sh config/zookeeper.properties
続いて、kafkaサーバを立ち上げます。これはbrokerを指しています。
$ bin/kafka-server-start.sh config/server.properties
topicを作成してみます。ここでは例として３つほど作成してみます。
$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test
Created topic "test".
$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test2
Created topic "test2".
$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test3
Created topic "test3".
上記のオプションについて簡単に説明します。
- replication-factor
- kafkaクラスタ内に存在するkafkaブローカーの何台にトピックを作成するか指定できます、なのでkafkaブローカーが1つしかない場合は1以上は指定できません
- partitions
- topicをいくつのパーティションに分割するかを指定します。
続いて、登録されているすべてのトピックを確認します。
$ bin/kafka-topics.sh --list --zookeeper localhost:2181
test
test2
test3
作成したトピックtestに対してメッセージを送信してみます。 「Hello world! This is test message of test」というのはここで入力するメッセージとなる。
$ bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test
Hello world!
This is test message of test
(ここで Ctrl + Dを押すと終了する)
続いて、consumerを立ち上げてみることにする。少し待つと先ほど送信したデータが表示されるようになる。
「–from-beginning」を指定するとトピックに送信されたメッセージを最初からすべて取得することができます。
なお、接続した時点からのメッセージのみを取得したい場合は「–from-beginning」オプションを指定しないことにより取得できます。
$ bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning
Hello world!
This is test message of test
ややわかりにくいのでメモしておくことにする。testというトピックを削除することを想定としている。
$ kafka-topics.sh --delete --zookeeper localhost:2181 --topic test
$ bin/kafka-topics.sh --list --zookeeper localhost:2181
test - marked for deletion
test2
test3
実は「- marked for deletion」はマークが付けられただけで全く削除されていない。
この場合にはまずkafkaの設定ファイル/usr/local/etc/kafka/server.propertiesに次の1行が入っていることで削除が有効になっているかどうかを確認します。
delete.topic.enable=true
そして、設定を有効にさせるためにkafkaを再起動します。これでtopicが削除できるようになります。(多分、zookeeperの再起動は不要なはず...)
$ kafka-server-stop.sh /usr/local/etc/kafka/server.properties
先ほど実行したtestトピック削除してlistで確認します。
$ kafka-topics.sh --delete --zookeeper localhost:2181 --topic test
$ kafka-topics.sh --list --zookeeper localhost:2181
listでの表示は少し(10秒程度!?)待たないと反映されないことがあります。 消えない場合には、kafkaのconsumerが接続されている可能性が高いのですべてのconsumerを停止してください。
例えば、testというトピックの詳細を確認して次の出力となった場合
$ bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic test
Topic:test PartitionCount:1 ReplicationFactor:3 Configs:
Topic:test Partition:0 Leader:0 Replicas:0,2,1 Isr:0,2,1
- PartitionCountはこのトピックを何台で保持しているかを表す。
- "Leader" is the node responsible for all reads and writes for the given partition. Each node will be the leader for a randomly selected portion of the partitions.
- "Replicas" is the list of nodes that replicate the log for this partition regardless of whether they are the leader or even if they are currently alive.
- "Isr" is the set of "in-sync" replicas. This is the subset of the replicas list that is currently alive and caught-up to the leader.
$ bin/kafka-topics.sh —zookeeper localhost:2181 --alter --topic topic_name --parti-tions count
$ bin/kafka-topics.sh
Create, delete, describe, or change a topic.
Option Description
------ -----------
--alter Alter the number of partitions,
replica assignment, and/or
configuration for the topic.
--config <name=value> A topic configuration override for the
topic being created or altered.The
following is a list of valid
configurations:
cleanup.policy
compression.type
delete.retention.ms
file.delete.delay.ms
flush.messages
flush.ms
follower.replication.throttled.
replicas
index.interval.bytes
leader.replication.throttled.replicas
max.message.bytes
message.format.version
message.timestamp.difference.max.ms
message.timestamp.type
min.cleanable.dirty.ratio
min.compaction.lag.ms
min.insync.replicas
preallocate
retention.bytes
retention.ms
segment.bytes
segment.index.bytes
segment.jitter.ms
segment.ms
unclean.leader.election.enable
See the Kafka documentation for full
details on the topic configs.
--create Create a new topic.
--delete Delete a topic
--delete-config <name> A topic configuration override to be
removed for an existing topic (see
the list of configurations under the
--config option).
--describe List details for the given topics.
--disable-rack-aware Disable rack aware replica assignment
--force Suppress console prompts
--help Print usage information.
--if-exists if set when altering or deleting
topics, the action will only execute
if the topic exists
--if-not-exists if set when creating topics, the
action will only execute if the
topic does not already exist
--list List all available topics.
--partitions <Integer: # of partitions> The number of partitions for the topic
being created or altered (WARNING:
If partitions are increased for a
topic that has a key, the partition
logic or ordering of the messages
will be affected
--replica-assignment A list of manual partition-to-broker
<broker_id_for_part1_replica1 : assignments for the topic being
broker_id_for_part1_replica2 , created or altered.
broker_id_for_part2_replica1 :
broker_id_for_part2_replica2 , ...>
--replication-factor <Integer: The replication factor for each
replication factor> partition in the topic being created.
--topic <topic> The topic to be create, alter or
describe. Can also accept a regular
expression except for --create option
--topics-with-overrides if set when describing topics, only
show topics that have overridden
configs
--unavailable-partitions if set when describing topics, only
show partitions whose leader is not
available
--under-replicated-partitions if set when describing topics, only
show under replicated partitions
--zookeeper <urls> REQUIRED: The connection string for
the zookeeper connection in the form
host:port. Multiple URLS can be
given to allow fail-over.
実際に試せていないが有用そうなオプションを確認しておくことにする。(確認したkafkaのバージョンはkafka_2.11-0.10.1.0)
$ bin/kafka-console-consumer.sh
The console consumer is a tool that reads data from Kafka and outputs it to standard output.
Option Description
------ -----------
--blacklist <blacklist> Blacklist of topics to exclude from
consumption.
--bootstrap-server <server to connect REQUIRED (unless old consumer is
to> used): The server to connect to.
--consumer-property <consumer_prop> A mechanism to pass user-defined
properties in the form key=value to
the consumer.
--consumer.config <config file> Consumer config properties file. Note
that [consumer-property] takes
precedence over this config.
--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
--enable-systest-events Log lifecycle events of the consumer
in addition to logging consumed
messages. (This is specific for
system tests.)
--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.
This is the default.
--offset <consume offset> The offset id to consume from (a non-
negative number), or 'earliest'
which means from beginning, or
'latest' which means from end
(default: latest)
--partition <Integer: partition> The partition to consume from.
--property <prop> The properties to initialize the
message formatter.
--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 (only when using old
consumer): The connection string for
the zookeeper connection in the form
host:port. Multiple URLS can be
given to allow fail-over.
特に次のオプションが使えそうだ(topicやzookeeperなどの基本的なものを除く)
- blacklist
- whitelist
$ bin/kafka-console-producer.sh
Read data from standard input and publish it to Kafka.
Option Description
------ -----------
--batch-size <Integer: size> Number of messages to send in a single
batch if they are not being sent
synchronously. (default: 200)
--broker-list <broker-list> REQUIRED: The broker list string in
the form HOST1:PORT1,HOST2:PORT2.
--compression-codec [compression-codec] The compression codec: either 'none',
'gzip', 'snappy', or 'lz4'.If
specified without value, then it
defaults to 'gzip'
--key-serializer <encoder_class> The class name of the message encoder
implementation to use for
serializing keys. (default: kafka.
serializer.DefaultEncoder)
--line-reader <reader_class> The class name of the class to use for
reading lines from standard in. By
default each line is read as a
separate message. (default: kafka.
tools.
ConsoleProducer$LineMessageReader)
--max-block-ms <Long: max block on The max time that the producer will
send> block for during a send request
(default: 60000)
--max-memory-bytes <Long: total memory The total memory used by the producer
in bytes> to buffer records waiting to be sent
to the server. (default: 33554432)
--max-partition-memory-bytes <Long: The buffer size allocated for a
memory in bytes per partition> partition. When records are received
which are smaller than this size the
producer will attempt to
optimistically group them together
until this size is reached.
(default: 16384)
--message-send-max-retries <Integer> Brokers can fail receiving the message
for multiple reasons, and being
unavailable transiently is just one
of them. This property specifies the
number of retires before the
producer give up and drop this
message. (default: 3)
--metadata-expiry-ms <Long: metadata The period of time in milliseconds
expiration interval> after which we force a refresh of
metadata even if we haven't seen any
leadership changes. (default: 300000)
--old-producer Use the old producer implementation.
--producer-property <producer_prop> A mechanism to pass user-defined
properties in the form key=value to
the producer.
--producer.config <config file> Producer config properties file. Note
that [producer-property] takes
precedence over this config.
--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.
--queue-enqueuetimeout-ms <Integer: Timeout for event enqueue (default:
queue enqueuetimeout ms> 2147483647)
--queue-size <Integer: queue_size> If set and the producer is running in
asynchronous mode, this gives the
maximum amount of messages will
queue awaiting sufficient batch
size. (default: 10000)
--request-required-acks <request The required acks of the producer
required acks> requests (default: 1)
--request-timeout-ms <Integer: request The ack timeout of the producer
timeout ms> requests. Value must be non-negative
and non-zero (default: 1500)
--retry-backoff-ms <Integer> Before each retry, the producer
refreshes the metadata of relevant
topics. Since leader election takes
a bit of time, this property
specifies the amount of time that
the producer waits before refreshing
the metadata. (default: 100)
--socket-buffer-size <Integer: size> The size of the tcp RECV size.
(default: 102400)
--sync If set message send requests to the
brokers are synchronously, one at a
time as they arrive.
--timeout <Integer: timeout_ms> If set and the producer is running in
asynchronous mode, this gives the
maximum amount of time a message
will queue awaiting sufficient batch
size. The value is given in ms.
(default: 1000)
--topic <topic> REQUIRED: The topic id to produce
messages to.
--value-serializer <encoder_class> The class name of the message encoder
implementation to use for
serializing values. (default: kafka.
serializer.DefaultEncoder)
- この辺をひとめぐり
- kafka-console-producer.sh, kafka-topics.sh, kafka-console-consumer.shコマンドのオプションをざっと使ってみるといいかもしれない