> In addition, users could set `isolation.level` `read_uncommitted` in `consumerProperties`, if don't need Druid to consume transactional topics or need Druid to consume older versions of Kafka.
> Make sure offsets are sequential, since there is no offset gap check in Druid anymore.
|`dataSchema`|The schema that will be used by the Kafka indexing task during ingestion. See [`dataSchema`](../../ingestion/index.md#dataschema) for details.|yes|
|`ioConfig`|A KafkaSupervisorIOConfig object for configuring Kafka connection and I/O-related settings for the supervisor and indexing task. See [KafkaSupervisorIOConfig](#kafkasupervisorioconfig) below.|yes|
|`tuningConfig`|A KafkaSupervisorTuningConfig object for configuring performance-related settings for the supervisor and indexing tasks. See [KafkaSupervisorTuningConfig](#kafkasupervisortuningconfig) below.|no|
### KafkaSupervisorIOConfig
|Field|Type|Description|Required|
|-----|----|-----------|--------|
|`topic`|String|The Kafka topic to read from. This must be a specific topic as topic patterns are not supported.|yes|
|`inputFormat`|Object|[`inputFormat`](../../ingestion/data-formats.md#input-format) to specify how to parse input data. See [the below section](#specifying-data-format) for details about specifying the input format.|yes|
|`consumerProperties`|Map<String,Object>|A map of properties to be passed to the Kafka consumer. See [next section](#more-on-consumerproperties) for more information.|yes|
|`pollTimeout`|Long|The length of time to wait for the Kafka consumer to poll records, in milliseconds|no (default == 100)|
|`replicas`|Integer|The number of replica sets, where 1 means a single set of tasks (no replication). Replica tasks will always be assigned to different workers to provide resiliency against process failure.|no (default == 1)|
|`taskCount`|Integer|The maximum number of *reading* tasks in a *replica set*. This means that the maximum number of reading tasks will be `taskCount * replicas` and the total number of tasks (*reading* + *publishing*) will be higher than this. See [Capacity Planning](#capacity-planning) below for more details. The number of reading tasks will be less than `taskCount` if `taskCount > {numKafkaPartitions}`.|no (default == 1)|
|`taskDuration`|ISO8601 Period|The length of time before tasks stop reading and begin publishing their segment.|no (default == PT1H)|
|`startDelay`|ISO8601 Period|The period to wait before the supervisor starts managing tasks.|no (default == PT5S)|
|`period`|ISO8601 Period|How often the supervisor will execute its management logic. Note that the supervisor will also run in response to certain events (such as tasks succeeding, failing, and reaching their taskDuration) so this value specifies the maximum time between iterations.|no (default == PT30S)|
|`useEarliestOffset`|Boolean|If a supervisor is managing a dataSource for the first time, it will obtain a set of starting offsets from Kafka. This flag determines whether it retrieves the earliest or latest offsets in Kafka. Under normal circumstances, subsequent tasks will start from where the previous segments ended so this flag will only be used on first run.|no (default == false)|
|`completionTimeout`|ISO8601 Period|The length of time to wait before declaring a publishing task as failed and terminating it. If this is set too low, your tasks may never publish. The publishing clock for a task begins roughly after `taskDuration` elapses.|no (default == PT30M)|
|`lateMessageRejectionStartDateTime`|ISO8601 DateTime|Configure tasks to reject messages with timestamps earlier than this date time; for example if this is set to `2016-01-01T11:00Z` and the supervisor creates a task at *2016-01-01T12:00Z*, messages with timestamps earlier than *2016-01-01T11:00Z* will be dropped. This may help prevent concurrency issues if your data stream has late messages and you have multiple pipelines that need to operate on the same segments (e.g. a realtime and a nightly batch ingestion pipeline).|no (default == none)|
|`lateMessageRejectionPeriod`|ISO8601 Period|Configure tasks to reject messages with timestamps earlier than this period before the task was created; for example if this is set to `PT1H` and the supervisor creates a task at *2016-01-01T12:00Z*, messages with timestamps earlier than *2016-01-01T11:00Z* will be dropped. This may help prevent concurrency issues if your data stream has late messages and you have multiple pipelines that need to operate on the same segments (e.g. a realtime and a nightly batch ingestion pipeline). Please note that only one of `lateMessageRejectionPeriod` or `lateMessageRejectionStartDateTime` can be specified.|no (default == none)|
|`earlyMessageRejectionPeriod`|ISO8601 Period|Configure tasks to reject messages with timestamps later than this period after the task reached its taskDuration; for example if this is set to `PT1H`, the taskDuration is set to `PT1H` and the supervisor creates a task at *2016-01-01T12:00Z*, messages with timestamps later than *2016-01-01T14:00Z* will be dropped. **Note:** Tasks sometimes run past their task duration, for example, in cases of supervisor failover. Setting earlyMessageRejectionPeriod too low may cause messages to be dropped unexpectedly whenever a task runs past its originally configured task duration.|no (default == none)|
This must contain a property `bootstrap.servers` with a list of Kafka brokers in the form: `<BROKER_1>:<PORT_1>,<BROKER_2>:<PORT_2>,...`.
By default, `isolation.level` is set to `read_committed`. It should be set to `read_uncommitted` if you don't want Druid to consume only committed transactions or working with older versions of Kafka servers with no Transactions support.
There are few cases that require fetching few/all of consumer properties at runtime e.g. when `bootstrap.servers` is not known upfront or not static, to enable SSL connections users might have to provide passwords for `keystore`, `truststore` and `key` secretly.
For such consumer properties, user can implement a [DynamicConfigProvider](../../operations/dynamic-config-provider.md) to supply them at runtime, by adding
Note: In 0.20.0 or older Druid versions, for SSL connections, the `keystore`, `truststore` and `key` passwords can also be provided as a [Password Provider](../../operations/password-provider.md). This is deprecated.
Kafka indexing service supports both [`inputFormat`](../../ingestion/data-formats.md#input-format) and [`parser`](../../ingestion/data-formats.md#parser) to specify the data format.
The `inputFormat` is a new and recommended way to specify the data format for Kafka indexing service,
but unfortunately, it doesn't support all data formats supported by the legacy `parser`.
(They will be supported in the future.)
The supported `inputFormat`s include [`csv`](../../ingestion/data-formats.md#csv),
[`delimited`](../../ingestion/data-formats.md#tsv-delimited), and [`json`](../../ingestion/data-formats.md#json).
You can also read [`avro_stream`](../../ingestion/data-formats.md#avro-stream-parser),
| `type` | String | The indexing task type, this should always be `kafka`. | yes |
| `maxRowsInMemory` | Integer | The number of rows to aggregate before persisting. This number is the post-aggregation rows, so it is not equivalent to the number of input events, but the number of aggregated rows that those events result in. This is used to manage the required JVM heap size. Maximum heap memory usage for indexing scales with maxRowsInMemory * (2 + maxPendingPersists). Normally user does not need to set this, but depending on the nature of data, if rows are short in terms of bytes, user may not want to store a million rows in memory and this value should be set. | no (default == 1000000) |
| `maxBytesInMemory` | Long | The number of bytes to aggregate in heap memory before persisting. This is based on a rough estimate of memory usage and not actual usage. Normally this is computed internally and user does not need to set it. The maximum heap memory usage for indexing is maxBytesInMemory * (2 + maxPendingPersists). | no (default == One-sixth of max JVM memory) |
| `maxRowsPerSegment` | Integer | The number of rows to aggregate into a segment; this number is post-aggregation rows. Handoff will happen either if `maxRowsPerSegment` or `maxTotalRows` is hit or every `intermediateHandoffPeriod`, whichever happens earlier. | no (default == 5000000) |
| `maxTotalRows` | Long | The number of rows to aggregate across all segments; this number is post-aggregation rows. Handoff will happen either if `maxRowsPerSegment` or `maxTotalRows` is hit or every `intermediateHandoffPeriod`, whichever happens earlier. | no (default == unlimited) |
| `intermediatePersistPeriod` | ISO8601 Period | The period that determines the rate at which intermediate persists occur. | no (default == PT10M) |
| `maxPendingPersists` | Integer | Maximum number of persists that can be pending but not started. If this limit would be exceeded by a new intermediate persist, ingestion will block until the currently-running persist finishes. Maximum heap memory usage for indexing scales with maxRowsInMemory * (2 + maxPendingPersists). | no (default == 0, meaning one persist can be running concurrently with ingestion, and none can be queued up) |
| `indexSpec` | Object | Tune how data is indexed. See [IndexSpec](#indexspec) for more information. | no |
| `indexSpecForIntermediatePersists`| | Defines segment storage format options to be used at indexing time for intermediate persisted temporary segments. This can be used to disable dimension/metric compression on intermediate segments to reduce memory required for final merging. However, disabling compression on intermediate segments might increase page cache use while they are used before getting merged into final segment published, see [IndexSpec](#indexspec) for possible values. | no (default = same as indexSpec) |
| `reportParseExceptions` | Boolean | *DEPRECATED*. If true, exceptions encountered during parsing will be thrown and will halt ingestion; if false, unparseable rows and fields will be skipped. Setting `reportParseExceptions` to true will override existing configurations for `maxParseExceptions` and `maxSavedParseExceptions`, setting `maxParseExceptions` to 0 and limiting `maxSavedParseExceptions` to no more than 1. | no (default == false) |
| `handoffConditionTimeout` | Long | Milliseconds to wait for segment handoff. It must be >= 0, where 0 means to wait forever. | no (default == 0) |
| `resetOffsetAutomatically` | Boolean | Controls behavior when Druid needs to read Kafka messages that are no longer available (i.e. when OffsetOutOfRangeException is encountered).<br/><br/>If false, the exception will bubble up, which will cause your tasks to fail and ingestion to halt. If this occurs, manual intervention is required to correct the situation; potentially using the [Reset Supervisor API](../../operations/api-reference.html#supervisors). This mode is useful for production, since it will make you aware of issues with ingestion.<br/><br/>If true, Druid will automatically reset to the earlier or latest offset available in Kafka, based on the value of the `useEarliestOffset` property (earliest if true, latest if false). Please note that this can lead to data being _DROPPED_ (if `useEarliestOffset` is false) or _DUPLICATED_ (if `useEarliestOffset` is true) without your knowledge. Messages will be logged indicating that a reset has occurred, but ingestion will continue. This mode is useful for non-production situations, since it will make Druid attempt to recover from problems automatically, even if they lead to quiet dropping or duplicating of data.<br/><br/>This feature behaves similarly to the Kafka `auto.offset.reset` consumer property. | no (default == false) |
| `workerThreads` | Integer | The number of threads that the supervisor uses to handle requests/responses for worker tasks, along with any other internal asynchronous operation. | no (default == min(10, taskCount)) |
| `chatThreads` | Integer | The number of threads that will be used for communicating with indexing tasks. | no (default == min(10, taskCount * replicas)) |
| `chatRetries` | Integer | The number of times HTTP requests to indexing tasks will be retried before considering tasks unresponsive. | no (default == 8) |
| `httpTimeout` | ISO8601 Period | How long to wait for a HTTP response from an indexing task. | no (default == PT10S) |
| `shutdownTimeout` | ISO8601 Period | How long to wait for the supervisor to attempt a graceful shutdown of tasks before exiting. | no (default == PT80S) |
| `offsetFetchPeriod` | ISO8601 Period | How often the supervisor queries Kafka and the indexing tasks to fetch current offsets and calculate lag. | no (default == PT30S, min == PT5S) |
| `segmentWriteOutMediumFactory` | Object | Segment write-out medium to use when creating segments. See below for more information. | no (not specified by default, the value from `druid.peon.defaultSegmentWriteOutMediumFactory.type` is used) |
| `intermediateHandoffPeriod` | ISO8601 Period | How often the tasks should hand off segments. Handoff will happen either if `maxRowsPerSegment` or `maxTotalRows` is hit or every `intermediateHandoffPeriod`, whichever happens earlier. | no (default == P2147483647D) |
| `logParseExceptions` | Boolean | If true, log an error message when a parsing exception occurs, containing information about the row where the error occurred. | no, default == false |
| `maxParseExceptions` | Integer | The maximum number of parse exceptions that can occur before the task halts ingestion and fails. Overridden if `reportParseExceptions` is set. | no, unlimited default |
| `maxSavedParseExceptions` | Integer | When a parse exception occurs, Druid can keep track of the most recent parse exceptions. "maxSavedParseExceptions" limits how many exception instances will be saved. These saved exceptions will be made available after the task finishes in the [task completion report](../../ingestion/tasks.md#reports). Overridden if `reportParseExceptions` is set. | no, default == 0 |
|bitmap|Object|Compression format for bitmap indexes. Should be a JSON object. See [Bitmap types](#bitmap-types) below for options.|no (defaults to Roaring)|
|metricCompression|String|Compression format for primitive type metric columns. Choose from `LZ4`, `LZF`, `uncompressed`, or `none`.|no (default == `LZ4`)|
|longEncoding|String|Encoding format for metric and dimension columns with type long. Choose from `auto` or `longs`. `auto` encodes the values using offset or lookup table depending on column cardinality, and store them with variable size. `longs` stores the value as is with 8 bytes each.|no (default == `longs`)|
|`type`|String|See [Additional Peon Configuration: SegmentWriteOutMediumFactory](../../configuration/index.html#segmentwriteoutmediumfactory) for explanation and available options.|yes|
`GET /druid/indexer/v1/supervisor/<supervisorId>/status` returns a snapshot report of the current state of the tasks managed by the given supervisor. This includes the latest
offsets as reported by Kafka, the consumer lag per partition, as well as the aggregate lag of all partitions. The
consumer lag per partition may be reported as negative values if the supervisor has not received a recent latest offset
response from Kafka. The aggregate lag value will always be >= 0.
The status report also contains the supervisor's state and a list of recently thrown exceptions (reported as
`recentErrors`, whose max size can be controlled using the `druid.supervisor.maxStoredExceptionEvents` configuration).
There are two fields related to the supervisor's state - `state` and `detailedState`. The `state` field will always be
one of a small number of generic states that are applicable to any type of supervisor, while the `detailedState` field
will contain a more descriptive, implementation-specific state that may provide more insight into the supervisor's
activities than the generic `state` field.
The list of possible `state` values are: [`PENDING`, `RUNNING`, `SUSPENDED`, `STOPPING`, `UNHEALTHY_SUPERVISOR`, `UNHEALTHY_TASKS`]
The list of `detailedState` values and their corresponding `state` mapping is as follows:
|Detailed State|Corresponding State|Description|
|--------------|-------------------|-----------|
|UNHEALTHY_SUPERVISOR|UNHEALTHY_SUPERVISOR|The supervisor has encountered errors on the past `druid.supervisor.unhealthinessThreshold` iterations|
|UNHEALTHY_TASKS|UNHEALTHY_TASKS|The last `druid.supervisor.taskUnhealthinessThreshold` tasks have all failed|
|UNABLE_TO_CONNECT_TO_STREAM|UNHEALTHY_SUPERVISOR|The supervisor is encountering connectivity issues with Kafka and has not successfully connected in the past|
|LOST_CONTACT_WITH_STREAM|UNHEALTHY_SUPERVISOR|The supervisor is encountering connectivity issues with Kafka but has successfully connected in the past|
|PENDING (first iteration only)|PENDING|The supervisor has been initialized and hasn't started connecting to the stream|
|CONNECTING_TO_STREAM (first iteration only)|RUNNING|The supervisor is trying to connect to the stream and update partition data|
|DISCOVERING_INITIAL_TASKS (first iteration only)|RUNNING|The supervisor is discovering already-running tasks|
|CREATING_TASKS (first iteration only)|RUNNING|The supervisor is creating tasks and discovering state|
|RUNNING|RUNNING|The supervisor has started tasks and is waiting for taskDuration to elapse|
|SUSPENDED|SUSPENDED|The supervisor has been suspended|
|STOPPING|STOPPING|The supervisor is stopping|
On each iteration of the supervisor's run loop, the supervisor completes the following tasks in sequence:
1) Fetch the list of partitions from Kafka and determine the starting offset for each partition (either based on the
last processed offset if continuing, or starting from the beginning or ending of the stream if this is a new topic).
2) Discover any running indexing tasks that are writing to the supervisor's datasource and adopt them if they match
the supervisor's configuration, else signal them to stop.
3) Send a status request to each supervised task to update our view of the state of the tasks under our supervision.
4) Handle tasks that have exceeded `taskDuration` and should transition from the reading to publishing state.
5) Handle tasks that have finished publishing and signal redundant replica tasks to stop.
6) Handle tasks that have failed and clean up the supervisor's internal state.
7) Compare the list of healthy tasks to the requested `taskCount` and `replicas` configurations and create additional tasks if required.
The `detailedState` field will show additional values (those marked with "first iteration only") the first time the
supervisor executes this run loop after startup or after resuming from a suspension. This is intended to surface
initialization-type issues, where the supervisor is unable to reach a stable state (perhaps because it can't connect to
Kafka, it can't read from the Kafka topic, or it can't communicate with existing tasks). Once the supervisor is stable -
that is, once it has completed a full execution without encountering any issues - `detailedState` will show a `RUNNING`
state until it is stopped, suspended, or hits a failure threshold and transitions to an unhealthy state.
`GET /druid/indexer/v1/supervisor/<supervisorId>/stats` returns a snapshot of the current ingestion row counters for each task being managed by the supervisor, along with moving averages for the row counters.
You can suspend and resume a supervisor using `POST /druid/indexer/v1/supervisor/<supervisorId>/suspend` and `POST /druid/indexer/v1/supervisor/<supervisorId>/resume`, respectively.
