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Troubleshooting Kafka AWS Pipelines

There are a number of factors that can contribute to Kafka pipeline errors. Some of the more common errors and solutions are provided below:

Error 1933: Cannot get source metadata for pipeline.

ERROR 1933 ER_EXTRACTOR_EXTRACTOR_GET_LATEST_OFFSETS: Cannot get source metadata for pipeline. Could not fetch Kafka metadata; are the Kafka brokers reachable from the Master Aggregator? ssl.ca.location is missing. Kafka error Local: Broker transport failure.

Error 1933 means that there is a communication error between SingleStoreDB and the Kafka broker.

The cause could be something as simple as the Kafka broker is offline. Some things to check are:

  • Broker Status: Confirm Kafka broker is in an online state.

  • Port number: check to see if the port number is open and not in use by any other connection endpoint.

  • Hostname: check if there is a typo in the hostname.

  • Firewall: verify the firewall's rules are configured to allow incoming and outgoing traffic on the correct port(s).

  • SSL configs: ensure that the SSL configurations are not missing and are correct.

How to Analyze the Debugging Log

This section shows how to enable debugging (if not already enabled), how to analyze the output to determine the cause, and assist in solving the error.

  1. Enable the engine variable: pipelines_extractor_debug_logging for verbose error logging.

    singlestore> set global pipelines_extractor_debug_logging=ON;
    Query OK, 0 rows affected (0.02 sec)
  2. Flush the extractor pools.

    singlestore> flush extractor pools;
    Query OK, 0 rows affected (0.00 sec)
  3. Run the CREATE PIPELINE statement and wait to see if the pipeline fails. Below is a Kafka broker unreachable sample error.

    CREATE PIPELINE my_pipeline as 
     LOAD DATA KAFKA 'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com/singlestore' 
     INTO TABLE messages;
    
    ****
    ERROR 1933 (HY000): Cannot get source metadata for pipeline.  
      Could not fetch Kafka metadata; are the Kafka brokers reachable from the Master Aggregator?  
      ssl.ca.location is missing. Kafka error Local: Broker transport failure.
  4. Run SHOW WARNINGS. The output provides information as to what is causing the error. As shown in this example output, there is no communication with the Kafka broker on ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092. This may be due to no usable broker is present or the broker is not running.

    singlestore> SHOW WARNINGS;
    
    ****
    +---------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
    | Level   | Code | Message                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
    +---------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
    | Warning | 1933 |
    --- TRUNCATED ---
     ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap: Selected for cluster connection: application metadata request (broker has 567 connection attempt(s))
    CONNECT [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: 127.0.0.1:9092/bootstrap: Received CONNECT op
    STATE [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: 127.0.0.1:9092/bootstrap: Broker changed state INIT -> TRY_CONNECT
    BROADCAST [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: Broadcasting state change
    
    ...
    
    "FAIL [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap: Connect to ipv4#192.xxx.x.xx:9092 failed: Connection refused (after 55ms in state CONNECT) (_TRANSPORT): identical to last error: error log suppressed
    STATE [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap: Broker changed state CONNECT -> DOWN"
    "CONNECT [thrd:main]: Not selecting any broker for cluster connection: still suppressed for 36ms: refresh unavailable topics
    METADATA [thrd:main]: Hinted cache of 1/1 topic(s) being queried
    METADATA [thrd:main]: Skipping metadata refresh of 1 topic(s): refresh unavailable topics: no usable brokers
    CONNECT [thrd:main]: Not selecting any broker for cluster connection: still suppressed for 36ms: no cluster connection"
    "CONNECT [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap: broker in state TRY_CONNECT connecting
    STATE [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap: Broker changed state TRY_CONNECT -> CONNECT
    BROADCAST [thrd:ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/bootstrap]: Broadcasting state change"
  5. To turn off pipelines_extractor_debug_logging:

    singlestore> SET GLOBAL pipelines_extractor_debug_logging = OFF;
    Query OK, 0 rows affected (0.04 sec)

When the variable pipelines_extractor_debug_logging is OFF, the warning messages are concise but still helpful. The output does not show all the available information. When this variable is ON, there is more information. Often an internet search will yield a solution based on the information provided in the output.

Curl the Endpoint to Check Connectivity

If using a SingleStoreDB Cloud private link, try accessing the endpoint you create that maps to the service endpoint by using: curl -v <endpoint>. Otherwise try curling the broker(s):

ubuntu@kafka:~$ curl -v ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092
*   Trying 196.xx.xx.xxx:9092...
* TCP_NODELAY set
* Connected to ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com (196.xx.xx.xxx) port 9092 (#0)
> GET / HTTP/1.1
> Host: ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092
> User-Agent: curl/7.68.0
> Accept: */*

If the endpoint connectivity is successful, but there is still an issue with communicating with the broker, contact SingleStore Support, they will be able to run a curl on the DNS entries from within the SingleStoreDB Cloud side on any instance in the same subnet.

Confirm IPs Are in the Allowlist

In the portal page, select the Firewall tab and look at the addresses in the Outbound list.

kafka-oubound-ips.png

See AWS VPC SecurityGroups for more details about configuring outbound traffic.

Confirm Listeners in Kafka server.properties is Correct

If the error: Cannot get source metadata for pipeline. Could not fetch Kafka metadata keeps occurring on pipeline creation, confirm that the hostname is correct in the Kafka server.properties file.

For example, a pipeline was created using the following DDL statement:

CREATE PIPELINE kafka
AS LOAD DATA KAFKA 
'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com/singlestore'
INTO TABLE messages;

This pipeline creation statement resulted in the following error:

ERROR 1933 ER_EXTRACTOR_EXTRACTOR_GET_LATEST_OFFSETS: Cannot get 
source metadata for pipeline. Could not fetch Kafka metadata; are the Kafka 
brokers reachable from the Master Aggregator? Ssl.ca.location is missing. 
Kafka error Local Broker transport failure

To rectify this error, the server.properties file will need to be edited to reflect the correct hostname and to check for any other missing or incorrect settings. The location of the server.properties file may differ based on the version of Linux and Kafka that are being used.

  1. Specify the broker’s hostname and include the port number it uses.

    listeners=PLAINTEXT://ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092
  2. Restart the broker:

    ubuntu@kafka:~/kafka/config$ sudo systemctl restart kafka
  3. Confirm the broker is running:

    ubuntu@kafka:~/kafka/config$ sudo systemctl status kafka | grep Active
       Active: active (running) since Wed 2022-12-21 01:29:29 UTC; 48s ago
  4. Try running the create pipeline statement again:

    CREATE PIPELINE kafka
    AS LOAD DATA KAFKA'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com/singlestore'
    INTO TABLE messages;
  5. Check if the pipeline is ingesting data from Kafka:

    STOP PIPELINE kafka;
    
    Test PIPELINE kafka LIMIT 1;
    
    ****
    singlestore> Test PIPELINE kafka limit 1;
    +----------------------+------------------------------------------------------------------------------------------------------+
    | id                   | tweet                                                                                                |                                                                                                                                                                                          
    +----------------------+------------------------------------------------------------------------------------------------------+ 
    | 1612846720953581568  | {"created_at":1673367598,"favorite_count":0,"id":1612846720953581568,"retweet_count":0,"text":"RT    |
    |                      | @YE0NSSI: never getting over mr. jazz and boracut https://t.co/sHjsOaQ21S","username":"angelyoongo"} |
    +----------------------+------------------------------------------------------------------------------------------------------+
    1 row in set (0.49 sec)

Failed to get watermark offsets from Kafka with error Local: Unknown partition

Troubleshooting an Error 1933 error when trying to create a pipeline:

singlestore> create pipeline debug as load data kafka 
ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092, 
ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9093/multibroker' 
into table messages;
ERROR 1933 (HY000): Cannot get source metadata for pipeline.  
Failed to get watermark offsets from Kafka with error Local: 
Unknown partition

Confirm all Kafka Brokers are Running

One potential cause of the watermark offsets error is the Kafka broker is not running.

In the example error above there are two brokers:

ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092 
ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9093

Confirm all brokers are running using the command sudo systemctl status <broker_name>. For demonstration purposes the broker names are broker1 and broker2.

The Kafka broker1 is active and running, broker2 is active but failed.

ubuntu@kafka:~/kafka/scripts$ sudo systemctl status broker1 | grep 
Active
     Active: active (running) since Wed 2023-01-04 01:01:56 UTC; 14min ago

ubuntu@kafka:~/kafka/scripts$ sudo systemctl status broker2 | grep 
Active
     Active: failed (Result: exit-code) since Wed 2023-01-04 01:01:04 UTC; 15min ago

Start the offline broker using the command: sudo systemctl start <broker_name>;.

ubuntu@kafka:~/kafka/scripts$ sudo systemctl start broker2

ubuntu@kafka:~/kafka/scripts$ sudo systemctl status broker2 | grep Active

   Active: active (running) since Wed 2023-01-04 01:26:21 UTC; 1min 14s ago

Once all the brokers have been started and are running, creating a pipeline should work.

singlestore> CREATE PIPELIN debug AS LOAD DATA kafka 
'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092, 
ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9093/multibroker' 
INTO TABLE messages;Query OK, 0 rows affected (0.35 sec)

Note

If all the brokers are in an offline state, the error would be: Error 1933:  Cannot get source metadata for pipeline.

ERROR 1970 ER_SUBPROCESS_TIMEOUT_ERROR:

Error 1970 usually occurs when trying to create a pipeline:

ERROR 1970 ER_SUBPROCESS_TIMEOUT_ERROR: Forwarding 
Error(node-xxx...): Remote connection timed out because no metadata 
was received from source. Stderr: <DATE> Batch starting with new 
consumer.rd_kafka_version_str

This is potentially caused by the AWS MSK broker endpoints when using Private Link with SingleStoreDB Cloud. Verify that the correct AWS MSK broker endpoints have been provided to the SingleStore Support Team.

ERROR 1933: Cannot get source metadata for pipeline.  Zero partitions for topic.  Topic may not exist, or it may still be being created.

The error shown below is  likely caused by a problem with the topic or the topic is still recovering from a broker reboot.

singlestore> system date
Thu Jan  5 23:38:30 UTC 2023
singlestore> CREATE PIPELINE debug AS LOAD DATA kafka 
'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/debug' 
INTO TABLE messages;

ERROR 1933 (HY000): Cannot get source metadata for pipeline.  
Zero partitions for topic.  Topic may not exist, or it may still 
be being created.

Check Kafka’s server.log to cross-reference the timestamp when the error occurred with the information present in the Kafka logging. The log should provide helpful information regarding the error. In the  example below, there are traces about topic recovery:

ubuntu@kafka:~/kafka/logs$ rg debug server.log | rg -v multibroker | rg -v test | rg 23:3
[2023-01-05 23:38:29,975] INFO [LogLoader partition=debug-1, dir=/tmp/kafka-logs-broker0] Loading producer state till offset 51457 with message format version 2 (kafka.log.Log$)
[2023-01-05 23:38:29,975] INFO [LogLoader partition=debug-1, dir=/tmp/kafka-logs-broker0] Reloading from producer snapshot and rebuilding producer state from offset 51457 (kafka.log.Log$)
[2023-01-05 23:38:29,998] INFO [ProducerStateManager partition=debug-1] Loading producer state from snapshot file 'SnapshotFile(/tmp/kafka-logs-broker0/debug-1/00000000000000051457.snapshot,51457)' (kafka.log.ProducerStateManager)
[2023-01-05 23:38:30,034] INFO [LogLoader partition=debug-1, dir=/tmp/kafka-logs-broker0] Producer state recovery took 59ms for snapshot load and 0ms for segment recovery from offset 51457 (kafka.log.Log$)
[2023-01-05 23:38:30,049] INFO Completed load of Log(dir=/tmp/kafka-logs-broker0/debug-1, topicId=FeqyeH2ZR_28aMF1x40Z-g, topic=debug, partition=1, highWatermark=0, lastStableOffset=0, logStartOffset=0, logEndOffset=51457) with 1 segments in 107ms (5/17 loaded in /tmp/kafka-logs-broker0) (kafka.log.LogManager)
[2023-01-05 23:38:30,300] INFO [LogLoader partition=debug-0, dir=/tmp/kafka-logs-broker0] Loading producer state till offset 48543 with message format version 2 (kafka.log.Log$)
[2023-01-05 23:38:30,300] INFO [LogLoader partition=debug-0, dir=/tmp/kafka-logs-broker0] Reloading from producer snapshot and rebuilding producer state from offset 48543 (kafka.log.Log$)
[2023-01-05 23:38:30,300] INFO [ProducerStateManager partition=debug-0] Loading producer state from snapshot file 'SnapshotFile(/tmp/kafka-logs-broker0/debug-0/00000000000000048543.snapshot,48543)' (kafka.log.ProducerStateManager)
[2023-01-05 23:38:30,301] INFO [LogLoader partition=debug-0, dir=/tmp/kafka-logs-broker0] Producer state recovery took 1ms for snapshot load and 0ms for segment recovery from offset 48543 (kafka.log.Log$)
[2023-01-05 23:38:30,315] INFO Completed load of Log(dir=/tmp/kafka-logs-broker0/debug-0, topicId=FeqyeH2ZR_28aMF1x40Z-g, topic=debug, partition=0, highWatermark=0, lastStableOffset=0, logStartOffset=0, logEndOffset=48543) with 1 segments in 39ms (12/17 loaded in /tmp/kafka-logs-broker0) (kafka.log.LogManager)
[2023-01-05 23:38:35,951] INFO [Partition debug-0 broker=0] Log loaded for partition debug-0 with initial high watermark 48543 (kafka.cluster.Partition)
[2023-01-05 23:38:36,414] INFO [Partition debug-1 broker=0] Log loaded for partition debug-1 with initial high watermark 51457 (kafka.cluster.Partition)

A recovery topic is usually solved by running the CREATE PIPELINE command again.

singlestore> CREATE PIPELINE debug AS LOAD DATA kafka 
'ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092/debug'
INTO TABLE messages;
Query OK, 0 rows affected (0.05 sec)

Cannot get source metadata for pipeline.  Failed to get watermark offsets from Kafka with error Broker: Unknown topic or partition

If an error such as: Cannot get source metadata for pipeline.  Failed to get watermark offsets from Kafka with error Broker: Unknown topic or partition in the information_schema.pipelines_errors table start by checking the Kafka broker(s) server.log around the same time as the error.

*************************** 1. row ***************************
            DATABASE_NAME: kafka
           PIPELINE_NAME: debug
     ERROR_UNIX_TIMESTAMP: 1672960138.923225
               ERROR_TYPE: Error
               ERROR_CODE: 1933
            ERROR_MESSAGE: Cannot get source metadata for pipeline.  
Failed to get watermark offsets from Kafka with error Broker: Unknown 
topic or partition
               ERROR_KIND: Extract
                STD_ERROR: 2023-01-05 23:07:51.811 Batch starting 
with new consumer.  rd_kafka_version_str: 1.8.2-PRE6-4-gecdd4d-dirty
2023-01-05 23:08:58.869 Failed to get watermark offsets from Kafka
with error Broker: Unknown topic or partition_$_SERVER_ERROR: 
Failed to get watermark offsets from Kafka with error Broker: 
Unknown topic or partition

In the Kafka server.log there are recovery type traces around the time of the error in the information_schema.pipelines_errors table.

[2023-01-05 23:08:58,276] INFO Kafka version: 3.0.0 (org.apache.kafka.common.utils.AppInfoParser)
[2023-01-05 23:08:58,277] INFO Kafka commitId: 8cb0a5e9d3441962 (org.apache.kafka.common.utils.AppInfoParser)
[2023-01-05 23:08:58,277] INFO Kafka startTimeMs: 1672960138244 (org.apache.kafka.common.utils.AppInfoParser)
[2023-01-05 23:08:58,279] INFO [KafkaServer id=0] started (kafka.server.KafkaServer)
[2023-01-05 23:08:58,581] INFO [BrokerToControllerChannelManager broker=0 name=alterIsr]: 
     Recorded new controller, from now on will use broker ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092 
     (id: 0 rack: null) (kafka.server.BrokerToControllerRequestThread)
[2023-01-05 23:08:58,642] INFO [BrokerToControllerChannelManager broker=0 name=forwarding]: 
     Recorded new controller, from now on will use broker ec2-xx-xxx-xx-xx.us-west-2.compute.amazonaws.com:9092 
     (id: 0 rack: null) (kafka.server.BrokerToControllerRequestThread)
[2023-01-05 23:08:59,279] INFO [Partition debug-0 broker=0] Log loaded for partition debug-0 with initial high watermark 48543 (kafka.cluster.Partition)

Once the broker is online and fully recovered, confirm if the problematic Kafka pipeline has stop printing the unknown topic or partition errors to the information_schema.pipelines_errors table.