카프카 운영 - 컨슈머의 오프셋 정보 변경하기

 들어가며

 프로듀서가 메세지를 발행하는 과정에서 에러가 발생하여, 컨슈머가 해당 메세지를 소비하지 못하고 Hang이 걸리는 경우가 있다(고승범님 글 참조). 이러한 경우 컨슈머의 오프셋 정보를 강제로 변경할 필요가 있다. 이 글에서는 브로커 CLI 환경에서 오프셋 정보를 변경하는 방법에 대해 살펴본다.

오프셋 정보 변경하기

메세지 발행/구독

• 프로듀서에 메세지 발행

# 발행할 메세지 입력
/usr/bin/kafka-console-producer --broker-list kafka-server-host:9092 --topic donald-offset-update
> ...

• 컨슈머에서 메세지 구독 (-> 오프셋 최신화)

# 브로커에 쌓인 메세지 구독
/usr/bin/kafka-console-consumer --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --topic donald-offset-update
> ...

각 파티션의 offset 10 감소

• Before
  • 50개의 메세지를 3개의 파티션이 17개 정도씩 나눠가진 상태
  • 컨슈머가 파티션의 모든 메세지를 가져감 (LAG = 0, CURRENT-OFFSET = LOG-END-OFFSET)

# 토픽(파티션) 상태
/usr/bin/kafka-consumer-groups --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --offsets --describe
Consumer group 'donald-consumer-group' has no active members.

GROUP                 TOPIC                PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
donald-consumer-group donald-offset-update 0          17              17              0               -               -               -
donald-consumer-group donald-offset-update 1          18              18              0               -               -               -
donald-consumer-group donald-offset-update 2          15              15              0               -               -               -

• After
  • CURRENT-OFFSET 이 10 감소
  • 각 파티션의 LAG = 10

# 오프셋 -10 이동
/usr/bin/kafka-consumer-groups --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --reset-offsets --shift-by -10 --topic donald-offset-update --execute

GROUP                          TOPIC                          PARTITION  NEW-OFFSET     
donald-consumer-group          donald-offset-update           0          7              
donald-consumer-group          donald-offset-update           2          5              
donald-consumer-group          donald-offset-update           1          8    

# 토픽(파티션) 상태
/usr/bin/kafka-consumer-groups --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --offsets --describe
Consumer group 'donald-consumer-group' has no active members.

GROUP                 TOPIC                PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
donald-consumer-group donald-offset-update 0          7               17              10              -               -               -
donald-consumer-group donald-offset-update 1          8               18              10              -               -               -
donald-consumer-group donald-offset-update 2          5               15              10              -               -               -

# 메세지 구독
/usr/bin/kafka-console-consumer --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --topic donald-offset-update
> ... (10 * 3 개의 메세지)

각 파티션의 offset 처음으로 update

• 파티션의 가장 처음(오프셋 최소값)으로 오프셋 이동

# 오프셋 처음으로 이동
/usr/bin/kafka-consumer-groups --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --reset-offsets --to-earliest --topic donald-offset-update --execute

GROUP                          TOPIC                          PARTITION  NEW-OFFSET     
donald-consumer-group          donald-offset-update           0          0              
donald-consumer-group          donald-offset-update           2          0              
donald-consumer-group          donald-offset-update           1          0 

# 토픽(파티션) 상태
/usr/bin/kafka-consumer-groups --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --offsets --describe

Consumer group 'donald-consumer-group' has no active members.

GROUP                 TOPIC                PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
donald-consumer-group donald-offset-update 0          0               17              17              -               -               -
donald-consumer-group donald-offset-update 1          0               18              18              -               -               -
donald-consumer-group donald-offset-update 2          0               15              15              -               -               -

# 메세지 구독
/usr/bin/kafka-console-consumer --bootstrap-server kafka-server-host:9092 --group donald-consumer-group --topic donald-offset-update
> ... (전체 메세지)

기타 오프셋 이동 옵션

.----------------------.-----------------------------------------------.----------------------------------------------------------------------------------------------------------------------------------------------.
|      Scenario        |                   Arguments                   |                                                                    Example                                                                   |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset to Datetime    |  --to-datetime YYYY-MM-DDTHH:mm:SS.sss±hh:mm  |  Reset to first offset since 01 January 2017, 00:00:00 hrs: --reset-offsets –group test.group --topic foo --to-datetime 2017-01-01T00:00:00Z |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset by Duration    |  --by-duration  PnDTnHnMnS                    |  Reset to first offset since one week ago (from current timestamp): --reset-offsets --group test.group --topic foo --by-duration P7D         |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset to Earliest    |  --to-earliest                                |  Reset to earliest offset available: --reset-offsets --group test.group --topic foo --to-earliest                                            |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset to Latest      |  --to-latest                                  |  Reset to latest offset available: --reset-offsets --group test.group --topic foo --to-latest                                                |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset to Offset      |  --to-offset                                  |  Reset to offset 1 in all partitions: --reset-offsets --group test.group --topic foo --to-offset 1                                           |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Shift Offset by 'n'  |  --shift-by n                                 |  Reset to current offset plus 5 positions: --reset-offsets --group test.group –topic foo --shift-by 5                                        |
:----------------------+-----------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------:
| Reset from File      |  --from-file PATH_TO_FILE                     |  Reset using a file with reset plan: --reset-offsets --group test.group --from-file reset-plan.csv                                           |
'----------------------'-----------------------------------------------'----------------------------------------------------------------------------------------------------------------------------------------------'

참고

• Kafka 운영자가 말하는 Kafka 서버 실전 로그 분석 - 고승범
• how to change start offset for topic