RabbitMQ superstream ingestion

The rabbit stream indexing service allows you to configure supervisors on the Overlord to manage the creation and lifetime of RabbitMQ indexing tasks. These indexing tasks read events from a rabbit super-stream. The supervisor oversees the state of the indexing tasks to:

coordinate handoffs
manage failures
ensure that Druid maintains scalability and replication requirements
To use the rabbit stream indexing service, load the druid-rabbit-indexing-service community druid extension. See Loading community extensions for more information.

Submitting a supervisor spec

To use the rabbit stream indexing service, load the druid-rabbit-indexing-service extension on both the Overlord and the Middle Managers. Druid starts a supervisor for a dataSource when you submit a supervisor spec. Submit your supervisor spec to the following endpoint:

http://<OVERLORD_IP>:<OVERLORD_PORT>/druid/indexer/v1/supervisor

For example:

curl -X POST -H 'Content-Type: application/json' -d @supervisor-spec.json http://localhost:8090/druid/indexer/v1/supervisor

Where the file supervisor-spec.json contains a rabbit supervisor spec:

{
  "type": "rabbit",
  "spec": {
    "dataSchema": {
      "dataSource": "metrics-rabbit",
      "timestampSpec": {
        "column": "timestamp",
        "format": "auto"
      },
     "dimensionsSpec": {
        "dimensions": [],
        "dimensionExclusions": [
         "timestamp",
         "value"
       ]
      },
     "metricsSpec": [
        {
         "name": "count",
          "type": "count"
       },
       {
          "name": "value_sum",
          "fieldName": "value",
          "type": "doubleSum"
        },
       {
         "name": "value_min",
         "fieldName": "value",
         "type": "doubleMin"
       },
        {
          "name": "value_max",
         "fieldName": "value",
         "type": "doubleMax"
       }
     ],
     "granularitySpec": {
        "type": "uniform",
        "segmentGranularity": "HOUR",
        "queryGranularity": "NONE"
     }
   },
    "ioConfig": {
     "stream": "metrics",
     "inputFormat": {
       "type": "json"
      },
      "uri": "rabbitmq-stream://localhost:5552",
      "taskCount": 1,
      "replicas": 1,
      "taskDuration": "PT1H"
   },
   "tuningConfig": {
     "type": "rabbit",
     "maxRowsPerSegment": 5000000
   }
  }
}

Supervisor spec

Field	Description	Required
`type`	The supervisor type; this should always be `rabbit`.	yes
`spec`	Container object for the supervisor configuration.	yes
`dataSchema`	The schema that will be used by the rabbit indexing task during ingestion. See `dataSchema`.	yes
`ioConfig`	An `ioConfig` object for configuring rabbit super stream connection and I/O-related settings for the supervisor and indexing task.	yes
`tuningConfig`	A `tuningConfig` object for configuring performance-related settings for the supervisor and indexing tasks.	no

`ioConfig`

Field	Type	Description	Required
`stream`	String	The RabbitMQ super stream to read.	yes
`inputFormat`	Object	The input format to specify how to parse input data. See `inputFormat` for details.	yes
`uri`	String	The URI to connect to RabbitMQ with.	yes
`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.	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)
`useEarliestSequenceNumber`	Boolean	If a supervisor is managing a dataSource for the first time, it will obtain a set of starting sequence numbers from RabbitMQ. This flag determines whether it retrieves the earliest or latest sequence numbers in the stream. 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 == PT6H)
`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).	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)
`Consumer Properties`	Object	a dynamic map used to provide	no (default == none)

`tuningConfig`

The tuningConfig is optional. If no tuningConfig is specified, default parameters are used.

Field	Type	Description	Required
`type`	String	The indexing task type, this should always be `rabbit`.	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)`.	no (default == 100000)
`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 for more information.	no
`indexSpecForIntermediatePersists`	Object	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 for possible values.	no (default = same as `indexSpec`)
`reportParseExceptions`	Boolean	If true, exceptions encountered during parsing will be thrown and will halt ingestion; if false, unparseable rows and fields will be skipped.	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 RabbitMQ messages that are no longer available. Not supported.	no (default == false)
`skipSequenceNumberAvailabilityCheck`	Boolean	Whether to enable checking if the current sequence number is still available in a particular RabbitMQ stream. If set to false, the indexing task will attempt to reset the current sequence number (or not), depending on the value of `resetOffsetAutomatically`.	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))
`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)
`recordBufferSize`	Integer	Size of the buffer (number of events) used between the RabbitMQ consumers and the main ingestion thread.	no ( default == 100 MB or an estimated 10% of available heap, whichever is smaller.)
`recordBufferOfferTimeout`	Integer	Length of time in milliseconds to wait for space to become available in the buffer before timing out.	no (default == 5000)
`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 Druid saves. These saved exceptions are made available after the task finishes in the task completion report. Overridden if `reportParseExceptions` is set.	no, default == 0
`maxRecordsPerPoll`	Integer	The maximum number of records/events to be fetched from buffer per poll. The actual maximum will be `Max(maxRecordsPerPoll, Max(bufferSize, 1))`	no, default = 100
`repartitionTransitionDuration`	ISO8601 Period	When shards are split or merged, the supervisor will recompute shard -> task group mappings, and signal any running tasks created under the old mappings to stop early at (current time + `repartitionTransitionDuration`). Stopping the tasks early allows Druid to begin reading from the new shards more quickly. The repartition transition wait time controlled by this property gives the stream additional time to write records to the new shards after the split/merge, which helps avoid the issues with empty shard handling described at https://github.com/apache/druid/issues/7600.	no, (default == PT2M)
`offsetFetchPeriod`	ISO8601 Period	How often the supervisor queries RabbitMQ and the indexing tasks to fetch current offsets and calculate lag. If the user-specified value is below the minimum value (`PT5S`), the supervisor ignores the value and uses the minimum value instead.	no (default == PT30S, min == PT5S)

IndexSpec

Field	Type	Description	Required
bitmap	Object	Compression format for bitmap indexes. Should be a JSON object. See Bitmap types below for options.	no (defaults to Roaring)
dimensionCompression	String	Compression format for dimension columns. Choose from `LZ4`, `LZF`, or `uncompressed`.	no (default == `LZ4`)
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 sequence number 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`)

Bitmap types

For Roaring bitmaps:

Field	Type	Description	Required
`type`	String	Must be `roaring`.	yes

For Concise bitmaps:

Field	Type	Description	Required
`type`	String	Must be `concise`.	yes

SegmentWriteOutMediumFactory

Field	Type	Description	Required
`type`	String	See Additional Peon configuration: SegmentWriteOutMediumFactory for explanation and available options.	yes

Operations

This section describes how some supervisor APIs work in the Rabbit Stream Indexing Service. For all supervisor APIs, check Supervisor APIs.

RabbitMQ authentication

To authenticate with RabbitMQ securely, you must provide a username and password, as well as configure a certificate if you aren't using a standard certificate provider.

In order to configure these, use the dynamic configuration provider of the ioConfig:

  "ioConfig": {
    "type": "rabbit",
    "stream": "api-audit",
    "uri": "rabbitmq-stream://localhost:5552",
    "taskCount": 1,
    "replicas": 1,
    "taskDuration": "PT1H",
    "consumerProperties": {
        "druid.dynamic.config.provider" : {
            "type": "environment",
            "variables": {
                "username": "RABBIT_USERNAME",
                "password": "RABBIT_PASSWORD"
            }
        }
    }
  },

Submitting a supervisor spec​

Supervisor spec​

ioConfig​

tuningConfig​

IndexSpec​

Bitmap types​

SegmentWriteOutMediumFactory​

Operations​

RabbitMQ authentication​