Viewing and Resetting Kafka Consumption Offsets

A consumption offset indicates the consumption progress of a consumer. This section describes how to view and reset consumption offsets.

Messages may be retrieved more than once after the offset is reset. Exercise caution when performing this operation.

Prerequisites

The consumer offset cannot be reset on the fly. You must first stop retrieval of the desired consumer group.

After a client is stopped, the server considers the client offline only after the time period specified in ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG (1000 ms by default).

Viewing Consumer Offsets (Console)

Log in to the console.
Click in the upper left corner to select a region.

Select the region where your Kafka instance is located.
Click and choose Middleware > Distributed Message Service (for Kafka) to open the console of DMS for Kafka.
Click the desired Kafka instance to view the instance details.
In the navigation pane, choose Consumer Groups.
Click the name of the desired consumer group.
On the Consumer Offset tab page, view the list of topics that the consumer group has subscribed to, total number of messages accumulated in the topic, message consumption progress in each partition of the topic (accumulated messages, offset, latest offset, consumer ID, consumer address, and client ID).

Figure 1 Consumer offsets
(Optional) To query the consumer offsets of a specific topic, enter the topic name in the search box and press Enter.

Viewing Consumer Offsets (Kafka CLI)

For a Kafka instance with ciphertext access disabled, run the following command in the /bin directory of the Kafka client:

./kafka-consumer-groups.sh --bootstrap-server ${connection-address} --offsets --describe --all-groups

Parameter description: connection-address indicates the Kafka instance address, which can be obtained in the Connection area on the Basic Information page on the Kafka console.

Example:

[root@ecs-kafka bin]# ./kafka-consumer-groups.sh --bootstrap-server 192.168.xx.xx:9092,192.168.xx.xx:9092,192.168.xx.xx:9092 --offsets --describe --all-groups

Consumer group '__consumer-group-dial-test' has no active members.

GROUP                      TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
__consumer-group-dial-test __dms_dial_test 0          350             350             0               -               -               -
__consumer-group-dial-test __dms_dial_test 1          350             350             0               -               -               -
__consumer-group-dial-test __dms_dial_test 2          350             350             0               -               -               -

Consumer group 'test' has no active members.

GROUP           TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
test            topic-01        0          5               5               0               -               -               -
test            topic-01        1          3               3               0               -               -               -
test            topic-01        2          10              10              0               -               -               -
[root@ecs-kafka bin]#

For a Kafka instance with ciphertext access enabled, do as follows:

(Optional) Modify the client configuration file.
View Security Protocol in the Connection area on the Basic Information page on the Kafka console. The configuration settings vary depending on the protocol.
- SASL_PLAINTEXT: Skip this step if the username and password are already set. Otherwise, create the ssl-user-config.properties file in the /config directory on the Kafka client and add the following content to the file:
```
security.protocol=SASL_PLAINTEXT
# If the SASL mechanism is SCRAM-SHA-512, configure as follows:
sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=SCRAM-SHA-512
# If the SASL mechanism is PLAIN, configure as follows:
sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=PLAIN
```
  Parameter description: username and password are the ones you set when enabling ciphertext access for the first time or when creating a user.
- SASL_SSL: Skip this step if the username, password, and SSL certificate are already set. Otherwise, create the ssl-user-config.properties file in the /config directory on the Kafka client and add the following content to the file:
```
security.protocol=SASL_SSL
ssl.truststore.location={ssl_truststore_path}
ssl.truststore.password=dms@kafka
ssl.endpoint.identification.algorithm=
# If the SASL mechanism is SCRAM-SHA-512, configure as follows:
sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=SCRAM-SHA-512
# If the SASL mechanism is PLAIN, configure as follows:
sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=PLAIN
```
  Parameter description:
  - ssl.truststore.location: path for storing the client.jks certificate. Even in Windows, you need to use slashes (/) for the certificate path. Do not use backslashes (\), which are used by default for paths in Windows. Otherwise, the client will fail to obtain the certificate.
  - ssl.truststore.password: server certificate password, which must be set to dms@kafka and cannot be changed.
  - ssl.endpoint.identification.algorithm: whether to verify the certificate domain name. This parameter must be left blank, which indicates disabling domain name verification.
  - username and password: username and password you set when enabling ciphertext access for the first time or when creating a user.

Run the following command in the /bin directory of the Kafka client:

./kafka-consumer-groups.sh --bootstrap-server ${connection-address} --offsets --describe --all-groups --command-config ../config/ssl-user-config.properties

Parameter description: connection-address indicates the Kafka instance address, which can be obtained in the Connection area on the Basic Information page on the Kafka console.

Example:

[root@ecs-kafka bin]# ./kafka-consumer-groups.sh --bootstrap-server 192.168.xx.xx:9093,192.168.xx.xx:9093,192.168.xx.xx:9093 --offsets --describe --all-groups --command-config ../config/ssl-user-config.properties

Consumer group '__consumer-group-dial-test' has no active members.

GROUP                      TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
__consumer-group-dial-test __dms_dial_test 0          347             347             0               -               -               -
__consumer-group-dial-test __dms_dial_test 1          347             347             0               -               -               -
__consumer-group-dial-test __dms_dial_test 2          347             347             0               -               -               -

Consumer group 'test' has no active members.

GROUP           TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID     HOST            CLIENT-ID
test            topic-01        0          5               5               0               -               -               -
test            topic-01        1          3               3               0               -               -               -
test            topic-01        2          10              10              0               -               -               -
[root@ecs-kafka bin]#

Resetting Consumer Offsets

Log in to the console.
Click in the upper left corner to select a region.

Select the region where your Kafka instance is located.
Click and choose Middleware > Distributed Message Service (for Kafka) to open the console of DMS for Kafka.
Click the desired Kafka instance to view the instance details.
In the navigation pane, choose the Consumer Groups tab.
Click the name of the desired consumer group.
On the Consumer Offset tab page, you can perform the following operations:
- To reset the consumer offset of all partitions of a single topic, click Reset Consumer Offset in the row containing the desired topic.
- To reset the consumer offset of a single partition of a single topic, click Reset Consumer Offset in the row containing the desired partition.
- To reset the consumer offset of all partitions in all topics, click Reset Offset above the list.

In the displayed Reset Consumer Offset dialog box, set the parameters by referring to Table 1.

**Table 1** Parameters for resetting the consumer offset
Parameter	Description
Reset By	You can reset an offset by: Time: Reset the offset to the specified time. Offset: Reset the offset to the specified position. If you reset offsets in batches, they can only be reset to the specified time.
Time	Set this parameter if Reset By is set to Time. Select a time point. After the reset is complete, retrieval starts from this time point. Earliest: earliest offset Custom: a custom time point Latest: latest offset
Offset	Set this parameter if Reset By is set to Offset. Enter an offset, which is greater than or equal to 0. After the reset is complete, retrieval starts from this offset.