S3 Sink connector

The S3 Sink Connector is a Stateless NiFi dataflow developed by Cloudera that is running in the Kafka Connect framework. Learn about the connector, its properties, and configuration.

The S3 Sink connector fetches messages from Kafka and uploads them to AWS S3. The topic this connector receives messages from is determined by the value of the topics property in the configuration. The messages can contain unstructured (character or binary) data or they can be in Avro or JSON format.

If the input is unstructured data, record processing is disabled. In a case like this, multiple messages can be concatenated into a single output file on S3 using a demarcator (for example, newline for text messages). Merging is optional, large binary data can be forwarded to S3 at a 1:1 ratio, one Kafka message equals a single S3 object.

If the input is either Avro or JSON, record processing is enabled. In a case like this, the schema of the records can be a predefined schema retrieved from Schema Registry (for both Avro and JSON data), it can be embedded in the Avro data, or inferred from the JSON data. The output can be Avro, JSON, CSV or Parquet. Multiple records are typically merged into a single output file before uploading to S3.

The connector can authenticate to AWS using an Access Key.

Properties and configuration

Configuration is passed to the connector in a JSON file during creation. The properties of the connector can be categorized into three groups. These are as follows:

Common connector properties

These are the properties of the Kafka Connect framework that are accepted by all connectors. For a comprehensive list of these properties, see the Apache Kafka documentation.

Stateless NiFi Sink properties

These are the properties that are specific to the Stateless NiFi Sink connector. All Stateless NiFi Sink connectors share and accept these properties. For a comprehensive list of these properties, see the Stateless NiFi Sink properties reference.

Connector/dataflow-specific properties

These properties are unique to this specific connector. Or to be more precise, unique to the dataflow running within the connector. These properties use the following prefix:

parameter.[***CONNECTOR NAME***] Parameters:

For a comprehensive list of these properties, see the S3 Sink properties reference.

Notes and limitations

Required properties must be assigned a valid value even if they are not used in the particular configuration. If a required property is not used, either leave its default value, or completely remove the property from the configuration JSON.
If a property that has a default value is completely removed from the configuration JSON, the system uses the default value.
Properties not marked as required must be completely removed from the configuration JSON if not set.
Schema Branch and Schema Version can not be specified at the same time.
It is not recommended to configure the following combination of settings:
- Kafka Message Data Format = JSON
- Schema Access Strategy = Infer Schema
- Maximum Number of Entries > 1
- Output File Data Format = Avro
In case the input records do not strictly match to one schema (for example, one record has a missing field while the other records do not), schema inference determines a schema for each record, while batching the schemas together assigns only one schema to the entire batch. Because of this, there might be records in the batch that do not match with the schema that is assigned to the batch. This can be avoided by disabling batching with the Maximum Number of Entries set to 1.

Configuration example for fetching unstructured data

In this example, the connector fetches unstructured messages containing single line character data from Kafka. The connector concatenates the messages using newline characters as the demarcator. The files that the connector creates and uploads to ADLS are maximum 10 MB in size. The files are named according to the following pattern: messages_[***UUID***]. The connector authenticates to AWS using an Access Key.

{
 "connector.class": "org.apache.nifi.kafka.connect.StatelessNiFiSinkConnector",
 "meta.smm.predefined.flow.name": "S3 Sink",
 "meta.smm.predefined.flow.version": "1.0.0",
 "key.converter": "org.apache.kafka.connect.storage.StringConverter",
 "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
 "nexus.url": "https://repository.cloudera.com/artifactory/repo",
 "extensions.directory": "/tmp/nifi-stateless-extensions",
 "working.directory": "/tmp/nifi-stateless-working",
 "failure.ports": "PutS3Object Failure",
 "topics": "[***KAFKA TOPIC NAME***]",
 "parameter.S3 Sink Parameters:AWS Access Key ID": "[***ACCESS KEY ID***]",
 "parameter.S3 Sink Parameters:AWS Secret Access Key": "[***SECRET ACCESS KEY***]",
 "parameter.S3 Sink Parameters:S3 Region": "[***S3 REGION***]",
 "parameter.S3 Sink Parameters:S3 Bucket": "[***S3 Bucket***]",
 "parameter.S3 Sink Parameters:Maximum File Size": "10 MB",
 "parameter.S3 Sink Parameters:Kafka Message Data Format": "Raw",
 "parameter.S3 Sink Parameters:Output File Demarcator": "\n",
 "parameter.ADLS Sink Parameters:Output Filename Pattern": "messages_${filename.uuid}"
}

The following list collects the properties from the configuration example that must be customized for this use case.

topics: The name of the Kafka topic the connector fetches messages from.
AWS Access Key ID: The Access Key ID to use for authentication to AWS.
AWS Secret Access Key: The Secret Access Key to use for authentication to AWS.
S3 Region: The AWS Region of the S3 Bucket to upload data to.
S3 Bucket: The S3 Bucket to upload data to.
Maximum File Size: The maximum size of the output data file. In this example, the maximum size is 10 MB.
Kafka Message Data Format: The format of the messages the connector receives from Kafka. In this example, this property is set to Raw. This means that the connector expects unstructured text or binary data.
Output File Demarcator: Specifies the character sequence for demarcating (delimiting) message boundaries when multiple Kafka messages are ingested into an output file as raw messages. In this example, the property is set to \n (newline). This means that the newline character is used to separate the single line character data of the Kafka messages.
Output Filename Pattern: Specifies the structure of the name of the output file. This property accepts string literals (fixed text) as well as various expressions. In this example, the property is set to messages_${filename.uuid}.
messages_ is a string literal, ${filename.uuid} is an expression that inserts a generated UUID in the filename. As a result, the files are named according to the following pattern: messages_[***UUID***].

Configuration example for fetching JSON data

In this example, the connector fetches messages in JSON format from Kafka. The connector parses the JSON records and converts them to Avro format using the schema inferred from the JSON data. The schema is also embedded in the output file. The connector merges multiple records (all messages that are available for a single execution of the connector) into an Avro file, generates a name for the file using the following pattern data_[***TIMESTAMP***]_[***SEQUENCE***].avro, and uploads the file to S3. The connector authenticates to AWS using an Access Key.

{
 "connector.class": "org.apache.nifi.kafka.connect.StatelessNiFiSinkConnector",
 "meta.smm.predefined.flow.name": "S3 Sink",
 "meta.smm.predefined.flow.version": "1.0.0",
 "key.converter": "org.apache.kafka.connect.storage.StringConverter",
 "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
 "nexus.url": "https://repository.cloudera.com/artifactory/repo",
 "extensions.directory": "/tmp/nifi-stateless-extensions",
 "working.directory": "/tmp/nifi-stateless-working",
 "failure.ports": "PutS3Object Failure",
 "topics": "[***KAFKA TOPIC NAME***]",
 "parameter.S3 Sink Parameters:AWS Access Key ID": "[***ACCESS KEY ID***]",
 "parameter.S3 Sink Parameters:AWS Secret Access Key": "[***SECRET ACCESS KEY***]",
 "parameter.S3 Sink Parameters:S3 Region": "[***S3 REGION***]",
 "parameter.S3 Sink Parameters:S3 Bucket": "[***S3 BUCKET***]"
 "parameter.ADLS Sink Parameters:Kafka Message Data Format": "JSON",
 "parameter.ADLS Sink Parameters:Schema Access Strategy": "Infer Schema",
 "parameter.ADLS Sink Parameters:Schema Write Strategy": "Embed Avro Schema",
 "parameter.ADLS Sink Parameters:Output File Data Format": "Avro",
 "parameter.ADLS Sink Parameters:Output Filename Pattern": "data_${filename.timestamp}_${filename.sequence}.avro",
 "parameter.ADLS Sink Parameters:Output Filename Timestamp Format": "yyyyMMdd_HHmmss_SSS"
}

The following list collects the properties from the configuration example that must be customized for this use case.

topics: The name of the Kafka topic the connector fetches messages from.
AWS Access Key ID: The Access Key ID to use for authentication to AWS.
AWS Secret Access Key: The Secret Access Key to use for authentication to AWS.
S3 Region: The AWS Region of the S3 Bucket to upload data to.
S3 Bucket: The S3 Bucket to upload data to.
Kafka Message Data Format: The format of the messages the connector receives from Kafka. In this example, this property is set to JSON. This means that the connector expects JSON data.
Schema Access Strategy: Specifies the strategy used for determining the schema of the Kafka record. In this example, this property is set to Infer Schema, meaning that the schema is determined (inferred) from the JSON data.
Schema Write Strategy: Specifies whether the record schema is written to the output data file. In this example, this property is set to Embed Avro Schema, meaning that the schema is embedded in the output Avro file.
Output File Data Format: Specifies the format of the records written to the output file. In this example, this property is set to Avro, meaning that the output file format is Avro.
Output Filename Pattern: Specifies the structure of the name of the output file. This property accepts string literals (fixed text) as well as various expressions. In this example, the property is set to data_${filename.timestamp}_${filename.sequence}.avro.
data_, the underscore ( _ ), and .avro are string literals. ${filename.timestamp} and ${filename.sequence} are expressions. ${filename.timestamp} inserts the current timestamp in the filename. ${filename.sequence} inserts an incrementing sequence value in the filename. As a result, the files are named according to the following pattern: data_[***TIMESTAMP***]_[***SEQUENCE***].avro.
Output Filename Timestamp Format: Specifies the timestamp format used in the ${filename.timestamp} expression. The expression is used when generating the output filename.

Stateless NiFi Sink properties reference

Review the following reference for a comprehensive list of the connector properties that are specific to the Stateless NiFi Sink connector.

In addition to the properties listed here, Stateless NiFi connectors also accept the properties of the Kafka Connect framework. For a comprehensive list of these properties, see the Apache Kafka documentation.

attribute.prefix

Description: The prefix to add to the key of each header that matches the regular expression specified in headers.as.attributes.regex. For example, if the header key is MyHeader, its value is MyValue, headers.as.attributes.regex is set to My.*, and this property is set to kafka, the flowfile that is created for the Kafka message will have an attribute named kafka.MyHeader with a value of MyValue.
Default Value
Accepted Values
Required: false

dataflow.timeout

Description: Specifies the maximum amount of time to wait for the dataflow to complete. If the dataflow does not complete before this timeout, the thread is interrupted and the dataflow is considered as a failure. The session is rolled back and the connector retriggers the flow. Defaults to 60 seconds if not specified.
Default Value: 60 seconds
Accepted Values
Required: false

extensions.directory

Description: Specifies the directory that stores downloaded extensions. Extensions are the NAR (NiFi Archive) files containing the processors and controller services a flow might use. Since Stateless NiFi is only the NiFi engine, it does not contain any of the processors and controller services you might use in your flow. When deploying the connector with the custom flow, the system needs to download the specific extensions that your flow uses from Nexus (unless they are already present in this directory). These extensions are stored in this directory. Because the default directory might not be writable, and to aid in upgrade scenarios, Cloudera recommends that you always specify an extensions directory.
Default Value: /tmp/nifi-stateless-extensions
Accepted Values
Required: true

failure.ports

Description: A comma separated list of output ports that are considered as failure conditions. If any flowfile is routed to an output port specified in this property, the dataflow is considered a failure and the session is rolled back. After a set amount of time, the dataflow reattempts to process the Kafka record. Any data transferred to an output port that is not in the list of failure ports is discarded.
Because of how Stateless NiFi Sink connectors behave, even if a single flowfile ends up in an output port that is marked as failure, the entire sessions is rolled back with all messages in the batch. Furthermore, if a flowfile ends up in a failure port in each subsequent iteration, the result is an endless loop. With some sink connectors (for example. MQTT Sink) this is the desired behavior. For more information regarding this behavior, see Dataflow execution and scheduling.
Default Value
Accepted Values
Required: false

flow.snapshot

Description: Specifies the dataflow to run. When using Streams Messaging Manager to deploy a connector, the value you set in this property must be a JSON object. URLs, file paths, or escaped JSON strings are not supported when using Streams Messaging Manager. Alternatively, if using the Kafka Connect REST API to deploy a connector, this can be a file containing the dataflow, a URL that points to a dataflow, or a string containing the entire dataflow as an escaped JSON. Cloudera however, does not recommend using the Kafka Connect REST API to interact with this connector or Kafka Connect.
Default Value
Accepted Values
Required: true

headers.as.attributes.regex

Description: A Java regular expression that is evaluated against all Kafka record headers. Headers are added to the flowfile as an attribute if the header key matches the regular expression. The header key is used as the attribute name. The header value is used as the attribute value. Additionally, the name of the attribute can also contain an optional prefix which is defined by the attribute.prefix property.
Default Value
Accepted Values
Required: false

input.port

Description: The name of the input port in the NiFi dataflow that Kafka records are sent to. If the dataflow contains exactly one input port, this property is optional and can be omitted. However, if the dataflow contains multiple input ports, this property must be specified.
Default Value
Accepted Values
Required: false

krb5.file

Description: Specifies the krb5.conf file to use if the dataflow interacts with any services that are secured using Kerberos. Defaults to /etc/krb5.conf if not specified.
Default Value: /etc/krb5.conf
Accepted Values
Required: false

name

Description: The name of the connector. On the Streams Messaging Manager UI, the connector names are specified using the Enter Name field. The name that you enter in the Enter Name field is automatically set as the value of the name property when the connector is deployed. Because of this, the name property is omitted from the configuration template provided in Streams Messaging Manager. If you manually add the name property to the configuration in Streams Messaging Manager, ensure that the value you set matches the connector name specified in the Enter Name field. Otherwise, the connector fails to deploy.
Default Value
Accepted Values
Required: true

nexus.url

Description: Specifies the Base URL of the Nexus instance to source extensions from. If configuring a Nexus instance that has multiple repositories, include the name of the repository in the URL. For example, https://nexus-private.myorganization.org/nexus/repository/my-repository/. If the property is not specified, the necessary extensions (the ones used by the flow) must be provided in the extensions directory before deploying the connector.
Default Value
Accepted Values
Required: true

parameter.`[FLOW PARAMETER NAME]`

Description: Specifies a parameter to use in the dataflow. For example, assume that you have the following entry in your connector configuration "parameter.Directory": "/mydir". In a case like this, any parameter context in the dataflow that has a parameter named Directory gets the specified value (/mydir). If the dataflow has child process groups, and those child process groups have their own parameter contexts, the value is used for all parameter contexts that contain a parameter named Directory. Parameters can also be applied to specific parameter contexts only. This can be done by prefixing the parameter name (Directory) with the name of the parameter context followed by a colon. For example, parameter.My Context:Directory only applies the specified value for the Directory parameter in the Parameter Context named My Context.
Default Value
Accepted Values
Required: false

working.directory

Description: Specifies a directory on the Connect server that NiFi should use for unpacking extensions that it needs to perform the dataflow. The contents of extensions.directory are unpacked here. Defaults to /tmp/nifi-stateless-working if not specified.
Default Value: /tmp/nifi-stateless-working
Accepted Values
Required: false

S3 Sink properties reference

Review the following reference for a comprehensive list of the connector properties that are specific to the S3 Sink connector.

The properties listed in this reference must be added to the connector configuration with the following prefix:

parameter.[***CONNECTOR NAME***] Parameters:

In addition to the properties listed here, this connector also accepts certain properties of the Kafka Connect framework as well as the properties of the NiFi Stateless Sink connector. When creating a new connector using the Streams Messaging Manager UI, all valid properties are presented in the default configuration template. You can view the configuration template to get a full list of valid properties. In addition, for more information regarding the accepted properties not listed here, you can review the Apache Kafka documentation and the Stateless NiFi Sink properties reference.

Avro Schema Write Strategy

Description: Specifies whether the record schema is written to the output data file. Applicable only for Avro output (Output File Data Format is set to Avro).
Default Value: Embed Avro Schema
Accepted Values: Embed Avro Schema, Do Not Write Schema, HWX Content-Encoded Schema Reference
Required: false

AWS Access Key ID

Description: The Access Key ID to use for authentication to AWS.
Default Value
Accepted Values
Required: true

AWS Secret Access Key

Description: The Secret Access Key to use for authentication to AWS.
Default Value
Accepted Values
Required: true

Date Format

Description: Specifies the format to use when writing date fields to JSON or CSV.
Default Value: yyyy-MM-dd
Accepted Values
Required: true

Kafka Message Data Format

Description: Specifies the format of the messages the connector receives from Kafka. If set to Avro or JSON, record processing is enabled. Raw can be used for unstructured text or binary data
Default Value: Avro
Accepted Values: Avro, JSON, Raw
Required: true

Kerberos Keytab

Description: The fully-qualified filename of the kerberos keytab associated with the principal for accessing Schema Registry.
Default Value: The location of the default keytab which is empty and can only be used for unsecure connections.
Accepted Values
Required: true

Kerberos Principal

Description: The Kerberos principal used for authenticating to Schema Registry.
Default Value: default
Accepted Values
Required: true

Maximum File Size

Description: The maximum size of the output data file. No size limit is applied if this property is not specified. Example values: 100 MB, 1 GB.
Default Value
Accepted Values
Required: false

Maximum Number of Entries

Description: The maximum number of entries in the output data file. In the context of this property, entry can mean one of two things. If record processing is enabled (Kafka Message Data Format is set to Avro or JSON), an entry is a record. Otherwise, entry means a Kafka message. Set this property to 1 if you want to create a separate output file for each Kafka message.
Default Value: 1000000
Accepted Values
Required: true

Output File Data Format

Description: Specifies the format of the records written to the output file. Required when record processing is enabled (Kafka Message Data Format is set to Avro or JSON).
Default Value: Avro
Accepted Values: Avro, JSON, CSV, Parquet
Required

Output File Demarcator

Description: Specifies the character sequence for demarcating (delimiting) message boundaries when multiple Kafka messages are ingested into an output file as raw messages (no record processing). This property can only be used if Kafka Message Data Format is set to Raw. If you want to use newline as the delimiter, set this property to \n.
Default Value
Accepted Values
Required: false

Output Filename Pattern

Description

Specifies the structure of the name of the output file (S3 object name including the prefix). The pattern can contain string literal (fixed text) parts and one or more of the following expressions:

${filename.uuid}: Inserts a generated UUID in the filename.
${filename.timestamp}: Inserts the current timestamp in the filename.
${filename.sequence}: Inserts an incrementing sequence value in the filename.

In order to generate unique filenames, either ${filename.uuid} or ${filename.sequence} must be used in the pattern.

Examples:

data_${filename.uuid}.json
records_${filename.timestamp}_${filename.sequence}.avro

Default Value

${filename.uuid}

Accepted Values

Required

false

Output Filename Sequence Initial Value

Description: This property is used to configure the initial value of the ${filename.sequence} expression. The value you set in this property is not the initial value of the sequence. The sequence starts at the value of this property +1. For example, if you set this property to 0, the sequence starts at 1.
Default Value: 0
Accepted Values
Required: false

Output Filename Sequence Padding Length

Description: Specifies the length of the ${filename.sequence} expression in characters. If the sequence has fewer characters than the value set in this property, it is padded with zeros (0). Padding is added to the left of the sequence.
Default Value: 6
Accepted Values
Required: false

Output Filename Timestamp Format

Description: The timestamp format to use for the ${filename.timestamp} expression. For example, yyyyMMdd_HHmmss_SSS.
Default Value
Accepted Values
Required: false

Parquet Compression Type

Description: The type of compression used for writing parquet files. Required when Output File Data Format is Parquet.
Default Value: UNCOMPRESSED
Accepted Values: UNCOMPRESSED, SNAPPY, GZIP, LZO, BROTLI, LZ4, ZSTD
Required: false

S3 Bucket

Description: The name of the S3 Bucket where the output file is uploaded.
Default Value
Accepted Values
Required: false

S3 Region

Description: The Region of the S3 Bucket.
Default Value
Accepted Values
Required: true

S3 Storage Class

Description: The Storage Class to use for the output file on S3.
Default Value: Standard
Accepted Values: Standard, IntelligentTiering, StandardInfrequentAccess, OneZoneInfrequentAccess, Glacier, GlacierInstantRetrieval, DeepArchive, ReducedRedundancy
Required: true

Schema Access Strategy