IT 這行真的學無止境，理想上可以主動追技術，比被技術追上好
“I am free and that is why I am lost.”
― Franz Kafka
我是自由的，那就是我迷失的原因。
今天會實際帶大家創建一個 topic，接著用 producer 去新增資料，再用 consumer 去取得資料，最後是將這個 topic 刪除。
首先，第一步永遠是先打開一個終端機
cd /usr/local/Cellar/kafka/2.8.0/libexec
kafka-topic.sh 新增 topic$ kafka-topics --create --zookeeper 127.0.0.1:2181 --replication-factor 1 --partitions 1 --topic first_topic
Created topic first_topic
topic 命名需要注意：first_topic 跟 first.topic 視為相同的，官方建議是選擇其中一種用法統一使用，不要同時併用
如果你混用底線跟點，還是可以成功創建 topic 但會跳出警報：
$ kafka-topics --create --zookeeper 127.0.0.1:2181 --replication-factor 1 --partitions 1 --topic first_topic.123
WARNING: Due to limitations in metric names, topics with a period ('.') or underscore ('_') could collide. To avoid issues it is best to use either, but not both.
Created topic first_topic.123.
Kafka的每個指令都有很多可選選項(Option)，輸入指令即可查看
可以看到 topic 相關的指令很多，接下來幾天會盡量為大家用實際例子下去介紹
$ kafka-topics
Create, delete, describe, or change a topic.
Option Description
------ -----------
--alter Alter the number of partitions,
replica assignment, and/or
configuration for the topic.
--at-min-isr-partitions if set when describing topics, only
show partitions whose isr count is
equal to the configured minimum. Not
supported with the --zookeeper
option.
--bootstrap-server <String: server to REQUIRED: The Kafka server to connect
connect to> to. In case of providing this, a
direct Zookeeper connection won't be
required.
--command-config <String: command Property file containing configs to be
config property file> passed to Admin Client. This is used
only with --bootstrap-server option
for describing and altering broker
configs.
--config <String: 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.compaction.lag.ms
max.message.bytes
message.downconversion.enable
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. It is
supported only in combination with --
create if --bootstrap-server option
is used (the kafka-configs CLI
supports altering topic configs with
a --bootstrap-server option).
--create Create a new topic.
--delete Delete a topic
--delete-config <String: name> A topic configuration override to be
removed for an existing topic (see
the list of configurations under the
--config option). Not supported with
the --bootstrap-server option.
--describe List details for the given topics.
--disable-rack-aware Disable rack aware replica assignment
--exclude-internal exclude internal topics when running
list or describe command. The
internal topics will be listed by
default
--force Suppress console prompts
--help Print usage information.
--if-exists if set when altering or deleting or
describing 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). If not supplied
for create, defaults to the cluster
default.
--replica-assignment <String: 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. If not supplied, defaults
to the cluster default.
--topic <String: topic> The topic to create, alter, describe
or delete. It also accepts a regular
expression, except for --create
option. Put topic name in double
quotes and use the '\' prefix to
escape regular expression symbols; e.
g. "test\.topic".
--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-min-isr-partitions if set when describing topics, only
show partitions whose isr count is
less than the configured minimum.
Not supported with the --zookeeper
option.
--under-replicated-partitions if set when describing topics, only
show under replicated partitions
--version Display Kafka version.
--zookeeper <String: hosts> DEPRECATED, The connection string for
the zookeeper connection in the form
host:port. Multiple hosts can be
given to allow fail-over.
$ kafka-topics --describe --topic first_topic --bootstrap-server localhost:9092
Topic: first_topic TopicId: Wvh3sCCoQ8mnfkKtDAiUIQ PartitionCount: 1 ReplicationFactor: 1 Configs: segment.bytes=1073741824
Topic: first_topic Partition: 0 Leader: 1 Replicas: 1 Isr: 1
這裡可以看到只有一行，是因為創建只有設定生成一個partition，明天會介紹創建多個 partition 的狀況
列出所有已經創建的 topics
指令：kafka-topics --list --bootstrap-server localhost:9092
$ kafka-topics --list --bootstrap-server localhost:9092
__consumer_offsets
connect-configs
connect-offsets
connect-status
first_topic
first_topic.123
Producer：在topic中輸入資料，利用 kafka-console-producer 指令會進入互動模式，可以手動輸入資料給 topic，如果要離開輸入 ctrl+c 即可
生產者這邊很單純只有兩個參數說明如下：
--topic：指定在哪個 topic 新增資料--bootstrap-server：指定要將資料塞到哪個 broker server$ kafka-console-producer --topic first_topic --bootstrap-server localhost:9092
>test123
>test456
>
Consumer：讀取指定 broker 的 topic 中的資料，一樣 ctrl+c 可離開
消費者這邊有三個參數介紹如下：
--topic：指定要消費的 topic--from-beginning：從該 topic 第一筆開始消費--bootstrap-server：指定要從哪個 broker server 消費，通常都會有多個 broker server$ kafka-console-consumer --topic first_topic --from-beginning --bootstrap-server localhost:9092
test123
test456
^CProcessed a total of 2 messages
建立完 topic，如果需要刪除 topic，刪除動作是由 TopicDeletionManager 負責，刪除的前提是設定檔的 delete.topic.enable 設定為 true
$ kafka-server-start /usr/local/etc/kafka/server-1.properties \
--override delete.topic.enable=true \
--override broker.id=100 \
--override log.dirs=/tmp/kafka-logs-100 \
--override port=9195 \
--override listeners=PLAINTEXT://localhost:9195
$ kafka-topics --bootstrap-server localhost:9195 \
--create \
--topic wait-for-remove \
--partitions 1 \
--replication-factor 1
Created topic “wait-for-remove”.
kafka-topics.sh --list 列出所有的 topic$ kafka-topics --zookeeper localhost:2181 --list
__consumer_offsets
wait-for-remove
kafka-topics.sh --describe 查詢 topic wait-for-remove 的資訊$ kafka-topics --zookeeper localhost:2181 --describe --topic wait-for-remove
Topic:wait-for-remove PartitionCount:1 ReplicationFactor:1 Configs:
Topic: wait-for-remove Partition: 0 Leader: 100 Replicas: 100 Isr: 100
=> 這邊可以看到 broker 100 是 topic wait-for-remove 唯一一個 partition 0 的 partition leader
$ kafka-server-start /usr/local/etc/kafka/server-1.properties \
--override delete.topic.enable=true \
--override broker.id=200 \
--override log.dirs=/tmp/kafka-logs-200 \
--override port=9196 \
--override listeners=PLAINTEXT://localhost:9196
kafka-topics.sh --delete把 topic wait-for-remove 刪掉$ kafka-topics --zookeeper localhost:2181 --delete --topic wait-for-remove
Topic wait-for-remove is marked for deletion.
Note: This will have no impact if delete.topic.enable is not set to true.
kafka-topics.sh --list 列出所有的 topic$ kafka-topics --zookeeper localhost:2181 --list
__consumer_offsets
wait-for-remove - marked for deletion
從這裡你可以看到kafka-topics.sh —delete只有在 topic 的 leader broker還活著的時候、而且delete.topic.enable是開啟的情況下才會執行，但是我們剛剛已經將 broker 100 關閉，這個等待被記錄的 topic 會被記錄在 zookeeper 中。
zkCli -server localhost:2181
Connecting to localhost:2181
Welcome to ZooKeeper!
JLine support is enabled
WATCHER::
WatchedEvent state:SyncConnected type:None path:null
[zk: localhost:2181(CONNECTED) 0] ls /admin/delete_topics
[wait-for-remove]
只要 broker 100 不啟動，topic wait-for-remove 就會維持這個標注的狀態
$ kafka-server-start /usr/local/etc/kafka/server-1.properties \
--override delete.topic.enable=true \
--override broker.id=100 \
--override log.dirs=/tmp/kafka-logs-100 \
--override port=9195 \
--override listeners=PLAINTEXT://localhost:9195
可以看到 log info 逐步地將 topic wait-for-remove 刪除掉
[2021-09-01 15:45:06,554] INFO [Partition wait-for-remove-0 broker=100] Log loaded for partition wait-for-remove-0 with initial high watermark 0 (kafka.cluster.Partition)
[2021-09-01 15:45:06,565] INFO [GroupCoordinator 100]: Removed 0 offsets associated with deleted partitions: wait-for-remove-0. (kafka.coordinator.group.GroupCoordinator)
[2021-09-01 15:45:06,567] INFO [GroupCoordinator 100]: Removed 0 offsets associated with deleted partitions: wait-for-remove-0. (kafka.coordinator.group.GroupCoordinator)
[2021-09-01 15:45:06,570] INFO [ReplicaFetcherManager on broker 100] Removed fetcher for partitions Set(wait-for-remove-0) (kafka.server.ReplicaFetcherManager)
[2021-09-01 15:45:06,570] INFO [ReplicaAlterLogDirsManager on broker 100] Removed fetcher for partitions Set(wait-for-remove-0) (kafka.server.ReplicaAlterLogDirsManager)
[2021-09-01 15:45:06,580] INFO [ReplicaFetcherManager on broker 100] Removed fetcher for partitions Set(wait-for-remove-0) (kafka.server.ReplicaFetcherManager)
[2021-09-01 15:45:06,580] INFO [ReplicaAlterLogDirsManager on broker 100] Removed fetcher for partitions Set(wait-for-remove-0) (kafka.server.ReplicaAlterLogDirsManager)
[2021-09-01 15:45:06,587] INFO Log for partition wait-for-remove-0 is renamed to /tmp/kafka-logs-100/wait-for-remove-0.bf17e83681d84b9bb50a4413bb0c461e-delete and is scheduled for deletion (kafka.log.LogManager)
[2021-09-01 15:45:06,588] INFO [broker-100-to-controller-send-thread]: Recorded new controller, from now on will use broker localhost:9092 (id: 0 rack: null) (kafka.server.BrokerToControllerRequestThread)
[2021-09-01 15:46:06,595] INFO [Log partition=wait-for-remove-0, dir=/tmp/kafka-logs-100] Deleting segments as the log has been deleted: LogSegment(baseOffset=0, size=0, lastModifiedTime=1630481740242, largestRecordTimestamp=None) (kafka.log.Log)
[2021-09-01 15:46:06,600] INFO [Log partition=rwait-for-remove-0, dir=/tmp/kafka-logs-100] Deleting segment files LogSegment(baseOffset=0, size=0, lastModifiedTime=1630481740242, largestRecordTimestamp=None) (kafka.log.Log)
[2021-09-01 15:46:06,604] INFO Deleted log /tmp/kafka-logs-100/wait-for-remove-0.bf17e83681d84b9bb50a4413bb0c461e-delete/00000000000000000000.log.deleted. (kafka.log.LogSegment)
[2021-09-01 15:46:06,610] INFO Deleted offset index /tmp/kafka-logs-100/wait-for-remove-0.bf17e83681d84b9bb50a4413bb0c461e-delete/00000000000000000000.index.deleted. (kafka.log.LogSegment)
[2021-09-01 15:46:06,611] INFO Deleted time index /tmp/kafka-logs-100/wait-for-remove-0.bf17e83681d84b9bb50a4413bb0c461e-delete/00000000000000000000.timeindex.deleted. (kafka.log.LogSegment)
[2021-09-01 15:46:06,617] INFO Deleted log for partition wait-for-remove-0 in /tmp/kafka-logs-100/wait-for-remove-0.bf17e83681d84b9bb50a4413bb0c461e-delete. (kafka.log.LogManager)
到此為止 topic 已經被刪除了
可以看到因為 topic wait-for-remove 已經被刪除了，所以ls出來的是空陣列
$ zkCli -server localhost:2181
Welcome to ZooKeeper!
JLine support is enabled
WATCHER::
WatchedEvent state:SyncConnected type:None path:null
[zk: localhost:2181(CONNECTED) 0] ls /admin/delete_topics
[]
想請問一下關於kafka-topics.sh --list相關問題
我看到有兩種指令是不同的分別為:
指令1: kafka-topics --list --bootstrap-server localhost:9092
指令2: kafka-topics --zookeeper localhost:2181 --list
這兩個差別在哪?
這個是看kafka版本，v2.2以上會改用bootstrap-server這樣去下指令，可以參考以下連結的範例 https://www.conduktor.io/kafka/kafka-topics-cli-tutorial/#Example-0
這篇文章蠻多語法在新版本kafka都不適用、需要調整了
剛剛自己查bootstrap-server為最新版本的指令
Kafka 2.2以上，關於刪除Topic是不是直接輸入kafka-topics --delete --topic <topic_name> --bootstrap-server <bootstrap_servers> 就可以了
iThome鐵人賽
看影片追技術