[doc]Add document for debug connector

[tuteng]

Fixes #3624

Master Issue: #3624

Motivation

If the current user encounters problems when using the connector, there is not a reasonable debugging process. This document attempts to provide a debugging process for the connector.

Modifications

• Add debugging document for the connector.

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation

[Jennifer88huang-zz]

@Anonymitaet Could you please help review this PR? Thank you.

[Anonymitaet]

@jennifer88huang glad to help

[sijie]

run java8 tests
run integration tests

[Anonymitaet]

The issue of Updating Connector Guide: #5015 (comment)

I've updated the guide based on the following structure:

[Anonymitaet]

Making plenty of modifications in a PR is not convenient, so I paste my writings here.
If you don't have comments, you can copy the following contents.

---

id: io-debug
title: How to debug Pulsar connectors
sidebar_label: Debug

This guide explains how to debug connectors in localrun or cluster mode and gives a debugging checklist.

To better demonstrate how to debug Pulsar connectors, here takes a Mongo sink connector as an example.

Deploy a Mongo sink environment

1. Start a Mongo service.

   docker pull mongo:4
   docker run -d -p 27017:27017 --name pulsar-mongo -v $PWD/data:/data/db mongo:4

2. Create a DB and a collection.

   docker exec -it pulsar-mongo /bin/bash
   mongo
   > use pulsar
   > db.createCollection('messages')
   > exit

3. Start Pulsar standalone.

   docker pull apachepulsar/pulsar:2.4.0
   docker run -d -it -p 6650:6650 -p 8080:8080 -v $PWD/data:/pulsar/data --link pulsar-mongo --name pulsar-mongo-standalone apachepulsar/pulsar:2.4.0 bin/pulsar standalone

4. Configure the Mongo sink with the mongo-sink-config.yaml file.

   configs:
   mongoUri: "mongodb://pulsar-mongo:27017"
   database: "pulsar"
   collection: "messages"
   batchSize: 2
   batchTimeMs: 500

   docker cp mongo-sink-config.yaml pulsar-mongo-standalone:/pulsar/

5. Download the Mongo sink nar package.

   docker exec -it pulsar-mongo-standalone /bin/bash
   curl -O http://apache.01link.hk/pulsar/pulsar-2.4.0/connectors/pulsar-io-mongo-2.4.0.nar

Debug in localrun mode

Start the Mongo sink in localrun mode using the localrun command.

Tip

For more information about the localrun command, see localrun.

./bin/pulsar-admin sinks localrun \
--archive pulsar-io-mongo-2.4.0.nar \ 
--tenant public --namespace default \
--inputs test-mongo \
--name pulsar-mongo-sink \
--sink-config-file mongo-sink-config.yaml \
--parallelism 1

Use connector log

Use one of the following methods to get a connector log in localrun mode:

• After executing the localrun command, the log is automatically printed on the console.

• The log is located at:

  logs/functions/tenant/namespace/function-name/function-name-instance-id.log

  Example

  The path of the Mongo sink connector is:

  logs/functions/public/default/pulsar-mongo-sink/pulsar-mongo-sink-0.log

To clearly explain the log information, here breaks down the large block of information into small blocks and add descriptions for each block.

• This piece of log information shows the storage path of the nar package after decompression.

  08:21:54.132 [main] INFO  org.apache.pulsar.common.nar.NarClassLoader - Created class loader with paths: [file:/tmp/pulsar-nar/pulsar-io-mongo-2.4.0.nar-unpacked/, file:/tmp/pulsar-nar/pulsar-io-mongo-2.4.0.nar-unpacked/META-INF/bundled-dependencies/,
  

  Tip

  If class cannot be found exception is thrown, check whether the nar file is decompressed in the folder file:/tmp/pulsar-nar/pulsar-io-mongo-2.4.0.nar-unpacked/META-INF/bundled-dependencies/ or not.

• This piece of log information illustrates the basic information about the Mongo sink connector, such as tenant, namespace, name, parallelism, resources, and so on, which can be used to check whether the Mongo sink connector is configured correctly or not.

  08:21:55.390 [main] INFO  org.apache.pulsar.functions.runtime.ThreadRuntime - ThreadContainer starting function with instance config InstanceConfig(instanceId=0, functionId=853d60a1-0c48-44d5-9a5c-6917386476b2, functionVersion=c2ce1458-b69e-4175-88c0-a0a856a2be8c, functionDetails=tenant: "public"
  namespace: "default"
  name: "pulsar-mongo-sink"
  className: "org.apache.pulsar.functions.api.utils.IdentityFunction"
  autoAck: true
  parallelism: 1
  source {
  typeClassName: "[B"
  inputSpecs {
      key: "test-mongo"
      value {
      }
  }
  cleanupSubscription: true
  }
  sink {
  className: "org.apache.pulsar.io.mongodb.MongoSink"
  configs: "{\"mongoUri\":\"mongodb://pulsar-mongo:27017\",\"database\":\"pulsar\",\"collection\":\"messages\",\"batchSize\":2,\"batchTimeMs\":500}"
  typeClassName: "[B"
  }
  resources {
  cpu: 1.0
  ram: 1073741824
  disk: 10737418240
  }
  componentType: SINK
  , maxBufferedTuples=1024, functionAuthenticationSpec=null, port=38459, clusterName=local)

• This piece of log information demonstrates the status of the connections to Mongo and configuration information.

  08:21:56.231 [cluster-ClusterId{value='5d6396a3c9e77c0569ff00eb', description='null'}-pulsar-mongo:27017] INFO  org.mongodb.driver.connection - Opened connection [connectionId{localValue:1, serverValue:8}] to pulsar-mongo:27017
  08:21:56.326 [cluster-ClusterId{value='5d6396a3c9e77c0569ff00eb', description='null'}-pulsar-mongo:27017] INFO  org.mongodb.driver.cluster - Monitor thread successfully connected to server with description ServerDescription{address=pulsar-mongo:27017, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[4, 2, 0]}, minWireVersion=0, maxWireVersion=8, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=89058800}

• This piece of log information explains the configuration of consumers and clients, including the topic name, subscription name, subscription type, and so on.

  08:21:56.719 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ConsumerStatsRecorderImpl - Starting Pulsar consumer perf with config: {
  "topicNames" : [ "test-mongo" ],
  "topicsPattern" : null,
  "subscriptionName" : "public/default/pulsar-mongo-sink",
  "subscriptionType" : "Shared",
  "receiverQueueSize" : 1000,
  "acknowledgementsGroupTimeMicros" : 100000,
  "negativeAckRedeliveryDelayMicros" : 60000000,
  "maxTotalReceiverQueueSizeAcrossPartitions" : 50000,
  "consumerName" : null,
  "ackTimeoutMillis" : 0,
  "tickDurationMillis" : 1000,
  "priorityLevel" : 0,
  "cryptoFailureAction" : "CONSUME",
  "properties" : {
      "application" : "pulsar-sink",
      "id" : "public/default/pulsar-mongo-sink",
      "instance_id" : "0"
  },
  "readCompacted" : false,
  "subscriptionInitialPosition" : "Latest",
  "patternAutoDiscoveryPeriod" : 1,
  "regexSubscriptionMode" : "PersistentOnly",
  "deadLetterPolicy" : null,
  "autoUpdatePartitions" : true,
  "replicateSubscriptionState" : false,
  "resetIncludeHead" : false
  }
  08:21:56.726 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ConsumerStatsRecorderImpl - Pulsar client config: {
  "serviceUrl" : "pulsar://localhost:6650",
  "authPluginClassName" : null,
  "authParams" : null,
  "operationTimeoutMs" : 30000,
  "statsIntervalSeconds" : 60,
  "numIoThreads" : 1,
  "numListenerThreads" : 1,
  "connectionsPerBroker" : 1,
  "useTcpNoDelay" : true,
  "useTls" : false,
  "tlsTrustCertsFilePath" : null,
  "tlsAllowInsecureConnection" : false,
  "tlsHostnameVerificationEnable" : false,
  "concurrentLookupRequest" : 5000,
  "maxLookupRequest" : 50000,
  "maxNumberOfRejectedRequestPerConnection" : 50,
  "keepAliveIntervalSeconds" : 30,
  "connectionTimeoutMs" : 10000,
  "requestTimeoutMs" : 60000,
  "defaultBackoffIntervalNanos" : 100000000,
  "maxBackoffIntervalNanos" : 30000000000
  }

Debug in cluster mode

You can use the following methods to debug a connector in cluster mode:

• Use connector log

• Use admin CLI

Use connector log

In cluster mode, multiple connectors can run on a worker. To find the log path of a specified connector, use the workerId to locate the connector log.

Use admin CLI

Pulsar admin CLI helps you debug Pulsar connectors with the following subcommands:

• get

• status

• topics stats

Create a Mongo sink

./bin/pulsar-admin sinks create \
--archive pulsar-io-mongo-2.4.0.nar \
--tenant public \
--namespace default \
--inputs test-mongo \
--name pulsar-mongo-sink \
--sink-config-file mongo-sink-config.yaml \
--parallelism 1

get

Use the get command to get the basic information about the Mongo sink connector, such as tenant, namespace, name, parallelism, and so on.

./bin/pulsar-admin sinks get --tenant public --namespace default  --name pulsar-mongo-sink
{
  "tenant": "public",
  "namespace": "default",
  "name": "pulsar-mongo-sink",
  "className": "org.apache.pulsar.io.mongodb.MongoSink",
  "inputSpecs": {
    "test-mongo": {
      "isRegexPattern": false
    }
  },
  "configs": {
    "mongoUri": "mongodb://pulsar-mongo:27017",
    "database": "pulsar",
    "collection": "messages",
    "batchSize": 2.0,
    "batchTimeMs": 500.0
  },
  "parallelism": 1,
  "processingGuarantees": "ATLEAST_ONCE",
  "retainOrdering": false,
  "autoAck": true
}

Tip

For more information about the get command, see get.

status

Use the status command to get the current status about the Mongo sink connector, such as the number of instance, the number of running instance, instanceId, workerId and so on.

./bin/pulsar-admin sinks status 
--tenant public \
--namespace default  \
--name pulsar-mongo-sink

{
"numInstances" : 1,
"numRunning" : 1,
"instances" : [ {
    "instanceId" : 0,
    "status" : {
    "running" : true,
    "error" : "",
    "numRestarts" : 0,
    "numReadFromPulsar" : 0,
    "numSystemExceptions" : 0,
    "latestSystemExceptions" : [ ],
    "numSinkExceptions" : 0,
    "latestSinkExceptions" : [ ],
    "numWrittenToSink" : 0,
    "lastReceivedTime" : 0,
    "workerId" : "c-standalone-fw-5d202832fd18-8080"
    }
} ]
}

Tip

For more information about the status command, see status.

If there are multiple connectors running on a worker, workerId can locate the worker on which the specified connector is running.

topics stats

Use the topics stats command to get the stats for a topic and its connected producer and consumer, such as whether the topic has received messages or not, whether there is a backlog of messages or not, the available permits and other key information. All rates are computed over a 1-minute window and are relative to the last completed 1-minute period.

./bin/pulsar-admin topics stats test-mongo
{
  "msgRateIn" : 0.0,
  "msgThroughputIn" : 0.0,
  "msgRateOut" : 0.0,
  "msgThroughputOut" : 0.0,
  "averageMsgSize" : 0.0,
  "storageSize" : 1,
  "publishers" : [ ],
  "subscriptions" : {
    "public/default/pulsar-mongo-sink" : {
      "msgRateOut" : 0.0,
      "msgThroughputOut" : 0.0,
      "msgRateRedeliver" : 0.0,
      "msgBacklog" : 0,
      "blockedSubscriptionOnUnackedMsgs" : false,
      "msgDelayed" : 0,
      "unackedMessages" : 0,
      "type" : "Shared",
      "msgRateExpired" : 0.0,
      "consumers" : [ {
        "msgRateOut" : 0.0,
        "msgThroughputOut" : 0.0,
        "msgRateRedeliver" : 0.0,
        "consumerName" : "dffdd",
        "availablePermits" : 999,
        "unackedMessages" : 0,
        "blockedConsumerOnUnackedMsgs" : false,
        "metadata" : {
          "instance_id" : "0",
          "application" : "pulsar-sink",
          "id" : "public/default/pulsar-mongo-sink"
        },
        "connectedSince" : "2019-08-26T08:48:07.582Z",
        "clientVersion" : "2.4.0",
        "address" : "/172.17.0.3:57790"
      } ],
      "isReplicated" : false
    }
  },
  "replication" : { },
  "deduplicationStatus" : "Disabled"
}

Tip

For more information about the topic status command, see topic status.

Checklist

This checklist indicates the major areas to check when you debug connectors. It is a reminder of what to look for to ensure a thorough review and an evaluation tool to get the status of connectors.

• Does Pulsar start successfully?

• Does the external service run normally?

• Is the nar package complete?

• Is the connector configuration file correct?

• In localrun mode, run a connector and check the printed information (connector log) on the console.

• In cluster mode：

  • Use the get command to get the basic information.

  • Use the status command to get the current status.

  • Use the topics stats command to get the stats for a specified topic and its connected producers and consumers.

  • Check the connector log.

• Enter into the external system and verify the result.

[Anonymitaet]

Please see my comments in conversation.

[Anonymitaet]

run cpp tests

[Anonymitaet]

run integration tests